Report to Humber INCA Institute of Estuarine and Coastal ...... · Estuarine and Coastal Studies...

Construction and Waterfowl:Defining Sensitivity, Response,

Impacts and Guidance

Report to Humber INCA

Institute of Estuarineand Coastal Studies

University of Hull

February 2009

Author(s): N. Cutts, A. Phelps& D. Burdon

Report: ZBB710-F-2009

Institute of Estuarine & Coastal Studies(IECS)The University of HullCottingham RoadHullHU6 7RXUK

Tel:+44 (0)1482 464120

Fax:+44 (0)1482 464130

E-mail:[email protected]

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Humber INCA

Construction and Waterfowl:Defining Sensitivity, Response,Impacts and Guidance

February 2009

Reference No: ZBB710-F-2009

For and on behalf of the Institute of

Estuarine and Coastal Studies

Approved by: N. Cutts

Signed:

Position: Deputy Director, IECS

Date: 04-02-09

This report has been prepared by theInstitute of Estuarine and CoastalStudies, with all reasonable care, skilland attention to detail as set within theterms of the Contract with the client.

We disclaim any responsibility to theclient and others in respect of anymatters outside the scope of the above.

This is a confidential report to the clientand we accept no responsibility ofwhatsoever nature to third parties towhom this report, or any part thereof, ismade known. Any such parties rely onthe report at their own risk.

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Construction and Waterfowl: Defining Sensitivity, Response, Impacts and GuidanceReport to Humber INCA

Page i Institute of Estuarine and Coastal Studies

TABLE OF CONTENTS

TABLE OF CONTENTS ............................................................................................................... I

1. INTRODUCTION...................................................................................................................1

1.1 Scope of the Project ................................................................................................1

1.1.1 Underlying Principles....................................................................................1

1.1.2 Approach......................................................................................................2

1.2 Aims and Objectives ................................................................................................3

2. METHODOLOGY..................................................................................................................5

2.1 Phase 1: Literature Review .....................................................................................5

2.2 Phase 2: Sensitivity Assessment ............................................................................5

3. SUMMARY OF FINDINGS ......................................................................................................7

3.1 Introduction ..............................................................................................................7

3.2 Human Presence .....................................................................................................7

3.2.1 Sensitivity of Foraging Birds to Human Activity.............................................8

3.2.2 Sensitivity of Roosting Birds to Human Activity...........................................10

3.2.3 Human Disturbance Effects on the Use of Migration Staging Areas...........11

3.2.4 Sensitivity of Nesting Birds to Human Disturbance.....................................11

3.3 Disturbance Responses to Fishing Activities and Bait Digging...............................12

3.4 Disturbance Responses to Boats and Watercraft ..................................................12

3.5 Disturbance Responses to Shooting Activity (Wildfowling & Military Activity) .........13

3.6 Disturbance Responses to Aircraft Noise...............................................................14

3.7 Roads and Traffic Noise ........................................................................................15

3.8 Construction...........................................................................................................15

3.8.1 Saltend.......................................................................................................15

3.8.2 South Humber Bank Power Station ............................................................17

3.9 Development Case Studies....................................................................................20

3.9.1 Tidal Barrage, Cardiff Bay ..........................................................................21

3.9.2 Proposed Tidal Barrage, Severn ................................................................21

3.9.3 Marina Construction, Hartlepool .................................................................21

3.9.4 Pipeline Construction, Clonakilty Bay .........................................................21

3.9.5 Harbour Development, Antwerp .................................................................22

3.9.6 Humber International Terminal (HIT) Construction, East Yorkshire, UK .....22

3.9.7 Wind Farms, General .................................................................................22

3.10 Climate Change ...................................................................................................22

3.11 Managed Realignment Sites (as compensation measures) .................................23

3.12 Predictive Models.................................................................................................23

3.13 Summary of Sensitivity with Recommended Mitigation Measures........................23

3.14 Species Approach Distance and Response Schematics ......................................31

4. SENSITIVITY ASSESSMENT FOR THE HUMBER .....................................................................35

4.1 Species Assemblage Sensitivity Parameters .........................................................35


Page ii Institute of Estuarine and Coastal Studies

4.1.1 Sensitivity of Humber waterfowl at Different Times of the Year (basket

assemblage) ............................................................................................35

4.1.2 Activities in Order of Severity of Disturbance on Waterbirds on the Humber37

4.1.3 Important Sectors on the Humber for Key Waterfowl Species....................39

4.1.4 Roost Sites on the Humber (based on data from, Mander & Cutts, 2006) ..43

4.2 Sensitivity Assessment Based on Sector Disturbance Parameters ........................55

4.2.1 Data Used ..................................................................................................55

4.2.2 Sectoral Sensitivity Scores for Anthropogenic Activities .............................69

4.3 Individual Waterfowl Sensitivity Values ..................................................................71

4.4 Total Sensitivity Values for the Humber .................................................................75

5. SUMMARY & RECOMMENDATIONS......................................................................................83

5.1 Addressing Issues of Concern ...............................................................................83

5.2 Summary of Literature Review...............................................................................85

5.3 Sensitivity Assessment ..........................................................................................86

5.4 Tool for Management and Decision Making ...........................................................87

6. REFERENCES...................................................................................................................90

APPENDICES ........................................................................................................................98

A1. INTRODUCTION TO LITERATURE REVIEW ............................................................................. I

A1.1 UK and Worldwide Estuaries .................................................................................. i

A1.1.1 Behavioural Responses to Direct Human Activity........................................ i

A1.1.2 Weather/Climate ......................................................................................viii

A1.1.3 Roosting.................................................................................................... ix

A1.1.4 Fishing and Shell Fishing Activity.............................................................. ix

A1.1.5 Wildfowling ............................................................................................... ix

A1.1.6 Aircraft Activity ........................................................................................... x

A1.1.7 Construction Disturbance and Case Studies.............................................. x

A1.1.8 Models ......................................................................................................xii

A1.1.9 Managed Realignment and Colonisation..................................................xvi

A1.2 UK and Worldwide Coasts..................................................................................xvii

A1.2.1 Behavioural Responses to Direct Human Activity................................... xviii

A1.2.2 Roosting............................................................................................... xxviii

A1.2.3 Aircraft Activity ..................................................................................... xxviii

A1.2.4 Boating Activity .......................................................................................xxx

A1.2.5 Wildfowling .............................................................................................xxx

A1.2.6 Construction Disturbance........................................................................xxx

A1.2.7 Models ...................................................................................................xxxi

A1.3 Offshore: UK and Worldwide ........................................................................... xxxiii

A1.4 Terrestrial UK and Worldwide......................................................................... xxxvii

A1.5 General Papers ...................................................................................................xlv


Page 1 Institute of Estuarine and Coastal Studies

1. INTRODUCTION

1.1 Scope of the Project

1.1.1 UNDERLYING PRINCIPLES

Disturbance may be defined as discrete events that disrupt ecosystem, community or

population structures or in some way alter resource levels, i.e. food and space, but it may

also influence the survival of individual birds and reduce the function of the site either for

roosting or feeding. Disturbance can be of an anthropogenic nature or may be natural in its

origin (fire, flooding or predator response). Anthropogenic disturbance is of most concern

as it is a form of disturbance that is probably less readily adapted to by species, but can be

managed if understood.

When considering disturbance impacts on overwintering bird populations, it is important to

address several crucial issues; the changes in the local distribution of the population

(displacement) and how these changes relate to total food supply, foraging efficiency and

compensation for increased energy expenditure due to flight (Riddington et al., 1996).

Disturbance varies in its magnitude, frequency, predictability, spatial distribution and

duration, moreover species vary greatly in their susceptibility to disturbance and this

susceptibility is likely to vary with age, season, weather and the degree of previous exposure

(Cayford, 1993).

The impact to waterfowl communities from anthropogenic activities on and around estuaries

has been identified as a potential issue for a many years. In particular, the potential impacts

of construction related activities on waterfowl populations associated with European Marine

Site assemblages has been considered a factor requiring quantification as part of the

consenting process, information on this often being required for inclusion within the

Environmental Impact Assessment (EIA) process, and, as necessary, for inclusion as

information to support the Appropriate Assessment process.

Clearly, some types of construction activity on or adjacent to the intertidal zone of an estuary

(and some adjacent terrestrial sites) have the potential to have an impact on the waterfowl

assemblage using the estuarine system in the vicinity. Such impacts would be from both

visual and aural stimuli, directly affecting receptors (waterfowl) within a zone of effect, as

well as at a wider level, through an indirect effect from alterations to function, usage patterns

and through displacement (with potential associated impacts to existing and displaced

communities).

The extent of this zone of impact will depend on a series of factors including the composition

of the waterfowl species assemblage present and the type(s) of avifaunal activity in the area

and existing habituation levels, as well as the type and ‘size’ of the stimuli (construction

activity), together with other exogenic abiotic factors such as the morphology of the area,

time of year and weather conditions.

The concept of carrying capacity is frequently used in terms of how the value of a site

outside the breeding season might be affected by a change in the management of the

resource it supplies usually the food supply or space availability. There is however some

conceptual ambiguity surrounding the notion of carrying capacity and thus it becomes



difficult to measure (Goss-Custard et al., 2002). It could be assumed that the closer the site

is to its ‘carrying capacity’ the more it will thus be affected by disturbance as there is less

available food and space to compensate for the time spent and lost by an individual whilst

avoiding the disturbance. This disturbance in turn, will therefore reduce a site’s potential

carrying capacity as the birds cannot fully utilise the area’s resources.

This becomes a significant problem when there are no alternative sites nearby, and birds are

forced to leave and estuary or stretch of coast altogether. This would imply that some

estuaries or coasts with high levels of disturbance may not be fulfilling their potential carrying

capacity as a direct result of disturbance. If alternative sites exist, local decreases in

abundance may be noted, but the carrying capacity of the estuary as a whole will not be

affected, highlighting the importance of alternative habitat, which acts as a retreat from local

disturbance.

Other factors may also affect the changing vulnerability of assemblages and species to

disturbance. For instance, some species, such as the Redshank (Tringa totanus) are

particularly sensitive to harsh weather conditions. Harsh weather puts an extra strain on an

individual to feed and thus disturbance will have a greater effect as the individual cannot

compensate for the time lost through disturbance avoidance. Prey availability is also a

factor, as birds will be more able to cope with a disturbance event if there is adequate prey

availability enabling compensatory feeding. Time of year is another factor influencing a

bird’s response to disturbance, birds are less habituated to disturbance in the spring and

autumn passage periods as they have often not had any recent experience of the

anthropogenic disturbance stimuli, thus behavioural responses will be greater. Such factors

will often lead to an increase in energy expenditure through flight responses and or reduced

roosting time, as well as reduced energy uptake due to reduced feeding time or increased

antagonistic behaviour (if forced into sub-optimal or compressed feeding areas). This will

have a detrimental effect on an individual’s energy budget which is especially critical during

hard weather periods (or times of migration movement) potentially leading to either mortality

or reduced breeding efficacy.

However, whilst it is relatively easy to broadly define the context of carrying capacity for

waterfowl on an estuary, it is more problematic to effectively measure it or identify metrics

that can be used as a proxy. Many studies have been carried out to model the effects of

displacement and habitat loss on foraging behaviour and carrying capacity e.g. West &

Caldow (2006); Stillman (2003), including their application on the Humber (e.g. Goss

Custard et al., (2008). However, for this study, the development and application of

stochastic or deterministic behavioural models and their outputs has been excluded from the

analysis, although, within an holistic management approach, the use of such models would

certainly have a degree of merit, and could be employed as part of a ‘tool box’ approach to

management.

1.1.2 APPROACH

The following text is therefore based primarily on direct behavioural data, either from

scientific study or from ad hoc observation. Where possible, the quality of the data have

been identified, and poor data excluded from the analysis. The report has two main sections

(these treated as Phases within the current study), the first being a literature review of

disturbance effects and avifauna with particular attention to construction and waterfowl, and



the second, a basic sensitivity analysis of the Humber, whereby an Environmental Integrative

Indicators (EII) approach has been developed, this approach consistent with development of

management strategies within an Ecosystem Approach framework. Details of the methods

employed and outcomes are given in the following sections.

1.2 Aims and Objectives

The main aims of this report have been twofold (and divided into two separate phases within

the project):

Provide a Literature Review and data synopsis for disturbance effects to

avifauna, and in particular, construction effects to waterfowl;

Provide a basic Sensitivity Analysis for the Humber estuary on a sectoral basis

use an EII approach.

The above have been derived in consultation with key stakeholder parties around the

Humber, including members of the industrial sector and conservation agencies. Key issues

and project scope were identified during a workshop hosted by Humber INCA on 11th

October 2007.

The workshop included a ‘brainstorming’ session, whereby attendees were split into two

groups and key issues were identified within each group. The findings of the identified the

following aspects as important to both groups:

Identify types of disturbance

Identify sensitive locations

Identify seasonal impacts

Identify which activities cause disturbance

With the following considered important by one of the groups:

Identify existing solutions

Identify gaps in knowledge

Identify existing data

Identify species characteristics / needs

Identify spatial / topographical effects

Identify where birds go when disturbed

Decide whether the available data can be extrapolated



Identify whether habituation to different disturbances occurs

The current study has therefore attempted to fully address the issues considered important

by both groups, and, where possible, also address the issues raised by one of the groups.



2. METHODOLOGY

2.1 Phase 1: Literature Review

The Literature Review has included information from scientific papers, applied research

studies and unpublished observational data. Where possible, the quality of the data has

been assessed, and, if necessary, some work disregarded. Where appropriate, tabulated

data from papers and reports have been included in this review, and full references

provided.

A bibliography has been compiled during the review process, and this can be provided in

digital format if required. A summary of the Literature Review including relevant findings are

provided in Section 3 of this report, with a more detailed review of the research reports

provided in Appendix 1.

The provision of data gathered by ABP during monitoring of their plans and projects on the

Humber is gratefully acknowledged, together with the provision of data from BP Chemicals,

South Humber Bank and the Environment Agency.

2.2 Phase 2: Sensitivity Assessment

A Sensitivity Assessment for the Humber was undertaken on a sectoral basis and focussing

on anthropogenic activities, waterfowl assemblage and species sensitivity and physical

parameters, these all affecting behavioural responses to construction activities by waterfowl.

The approach has been developed for the Humber using the existing WeBS sectors, as

these provide a readily available dataset for avifaunal communities, and are often delineated

to specific physical (topographic) parameters. An alternative approach using another

sectoral unit, for instance the management units described within the Humber SMP would

have some value within the management structure of the Humber system, but would be

constrained by the availability of appropriate waterfowl data.

Anthropogenic activities addressed on a sectoral basis within the Sensitivity Assessment

have included:

Ports and Other Industrial Activity

Adjacent Roads and Public Rights of Way

Wildfowling, Angling, Bait Digging and Cockle Collecting

In addition, the topography of the mudflats is included (e.g. mudflat width), together with a

waterfowl density figure. From these components, a series of index values have been

derived using an Environmental Integrative Indicators (EII) approach and these have then

been used to derive a basic Decision Support System based on EII values.

Such an approach could be developed further, using a more comprehensive suite of EIIs for

the Humber, along the lines of those described in Aubry & Elliott (2006) and Cutts (2008),



and these addressed in conjunction with a more detailed sectoral approach using GIS.

Details of this will be further discussed at the end of this report.

It should be noted that this report deals with disturbance events related to the estuarine

environment and associated avifaunal communities. It is recognised that disturbance does

occur outwith this area, but this has not been considered in this report.

It is also acknowledged that some of the information in this report has a ‘use by’ date and will

need reviewing in the future, both in the light of future research findings, and changes to the

ecosystem (e.g. the dynamic nature of populations and estuaries).



3. SUMMARY OF FINDINGS

A comprehensive literature review including information from scientific papers, applied

research studies and unpublished observational data was undertaken as part of this project.

This review presents a broad overall view of disturbance effects in different situations

effecting different species.

In order to provide a useful database of information regarding disturbance effects in coastal

areas, the following summary section refines and encapsulates available relevant research

literature with added examples of non-peer reviewed information relating to the observation

of disturbance impacts from construction projects.

A more comprehensive version of this review is provided in Appendix 1 and a bibliography

can be made available in digital form if required.

3.1 Introduction

Birds react to different disturbance stimuli in different ways. The main types of disturbance

are from human recreational activity, boats, aircraft, and construction and in some cases

roads and traffic noise. Birds will also be more sensitive to different types of disturbance at

different times of the day and year. In general the degree of disturbance on the avifauna of

a site will depend upon a number of variables including:

Type of disturbance stimuli

Avifaunal community present

Avifaunal function/activity

Extent and topography of site (spatial)

Time of year (temporal)

Level of third party disturbance

Weather conditions

Degree of previous exposure

This Section assesses the various responses to different disturbances and suggests

mitigation measures that may be used as conservation tools to manage and reduce these

disturbances. The effects and impacts of disturbance events on birds are discussed.

3.2 Human Presence

Studies show that birds respond to the presence of a human as they would a predator, by

avoidance, either walking or flying away from the assumed threat (Blumstein, 2003,

Blumstein et al., 2003). Energetic costs to the individual are imposed by engaging in

avoidance behaviours, thus birds asses risk dynamically and the distance at which a human



begins its approach will affect the distance at which birds initiate avoidance behaviour, i.e.

take flight. The response of the animal is seen as a trade-off between the risk of tolerating

the disturbance and the increased starvation risk from not feeding and avoiding (Stillman

and Goss-Custard, 2002).

The distance at which birds will initiate flight in response to a disturbance event varies inter-

specifically with some species, independent of site, with some reacting more strongly than

others. The Sanderling (Calidris alba) for example show 100% response to humans when

they are 30m or closer, this distance will be further for larger species such as the Curlew

(Numenius arquata). On the strength of this assessment, set-back distances and other

conservation tools should thus be set to the most sensitive of species with larger species in

general having greater alert distances (Blumstein et al., 2005).

Avoidance behaviour varies spatially and temporally depending on the prevailing local

conditions (Gill et al., 2001). Changes in behaviour, such as avoidance alone, may not

reflect how heavily a species is being affected by the presence of humans. The availability

of suitable habitat nearby will affect response to disturbance, a bird may be forced to endure

disturbance if there is no suitable alternative habitat nearby, regardless of the subsequent

impacts on its fitness. It is therefore important to focus on those species in decline as well

as those that appear particularly intolerant of disturbance. Individual based models,

consisting of fitness-maximising individuals, have been put forward to provide a link between

the behavioural responses to disturbance and population consequences measured in

reproductive success and mortality rates (Stillman et al., 2007).

3.2.1 SENSITIVITY OF FORAGING BIRDS TO HUMAN ACTIVITY

In general, the foraging behaviour of birds is negatively affected by the presence of humans.

The severities of these effects are partly dependant on:

Number of people present

Type of activity

Spatial variables

Temporal variables

Inter-specific differences.

Foraging birds react to disturbance in a number of different ways, and there are significant

inter-specific differences. Many species are seen to mitigate the effects of continued but

harmless disturbances by habituation; as they become used to the disturbance they react

less strongly. The Oystercatcher (Haematopus ostralegus) will walk away more frequently

but stops feeding less frequently in comparison to the Curlew. This suggests that plumage

crypsis is perhaps a factor in how the birds react to disturbance; birds better camouflaged

are more hidden when still and thus tend to walk away less often, waiting until they are

pushed to fly by the increasing perceived risk of predation.



In the presence of people, birds such as the Curlew, Redshank and Oystercatcher will

significantly delay their arrival times at a low water feeding site, with departures from these

feeding sites significantly earlier for the Redshank and the Oystercatcher when disturbed

(Fitzpatrick and Bouchez, 1998) reducing the time available for feeding.

In Sanderling, significant negative correlations between the time spent feeding and the time

Sanderling flew or ran because of people were observed (Burger and Gochfeld, 1991).

Birds that continue to feed throughout the night as the Sanderling does, (when time devoted

to human avoidance is less) can devote more time to feeding. Semi-palmated Plover

(Charadrius semipalmatus) were also seen to reduce feeding rates when there were people

present and feeding rates in the Oystercatcher were seen to be reduced from 33-50% as a

result of human disturbance (Goss-Custard and Verboven, 1993) this is however

compensated for by shifting to other areas and habituation.

Severe weather conditions reduce a bird’s tolerance to disturbance. The Oystercatcher can

withstand 1.0 - 1.5 disturbances per hour in winters with good feeding before fitness is

impaired, in comparison to 0.2 - 0.5 in winters with poorer feeding conditions (Goss-Custard

et al,. 2006). Redshank suffer the heaviest mortality amongst shorebird species around the

North Sea coasts of the UK. Redshank regulate body mass and, indirectly, fat reserves at

levels set as a trade-off between risks of perceived predation and starvation. Unlike other

waders the Redshank takes very small prey in relation to its body size and hence must feed

for longer periods during the tidal cycle to achieve their daily energy intake requirements, the

birds have no scope to extend feeding times during severe winter weather and are forced to

withstand the cold, depleting fat reserves (Mitchell et al., 2000). This leaves Redshank

particularly vulnerable to disturbance in such periods of severe weather. In addition, this can

be exacerbated by their prey preference, with the availability of key prey species often more

effected by hard weather than others, with prey either moving further down into the

substratum, out of reach of a Redshank’s bill, or the substratum itself freezing more readily,

as key feeding areas are often in the upper shore, which has a greater exposure to the air

(and potential to freeze).

Habitat usage affects the responses of foraging birds to human disturbance. The study by

Burger (1994) indicates that where a diversity of habitats exist, the Piping Plover (Charadrius

melodus) can reduce disturbance effects by allowing for movement between habitats to

minimise interactions with humans as their presence in numbers can reduce feeding time by

40% or more.

The type of activity may affect foraging birds in different ways, for example running or

walking or running with a dog. The type of recreational activity conducted by humans alone

does not significantly appear to affect foraging time in Sanderling; however the number of

people present did effect the time they spent foraging as did the presence of free running

dogs (Thomas et al., 2003).

1 To reduce disturbance, the numbers of people in an area where birds are feeding

should be limited as far as possible with larger parties maintaining greater distances

from foraging shorebirds

2 Free running dogs have significant negative correlation with time spent feeding and

leash laws should be put in place on regular feeding sites (Thomas et al., 2003).



3.2.2 SENSITIVITY OF ROOSTING BIRDS TO HUMAN ACTIVITY

Daily roosting is mainly attributed to wind speed, and the ability of the roost to provide

protection against wind (Peters and Otis, 2007) as well as the roost site’s proximity to

feeding grounds, with larger roosts being used more consistently.

Disturbance can be a factor in some species.

The main types of recreational disturbance by humans to wader roosts, based on evidence

from the Dee estuary, have been found to be:

walkers and

dogs (Kirby et al., 1993)

Most types of disturbance resulted in birds leaving the area with some species, the Grey

Plover (Pluvialis squatarola), Knot (Calidris canuta), Dunlin (Calidris alpina) and Bar-tailed

Godwit (Limosa lapponica) leaving the estuary altogether, and seemingly being more

sensitive to disturbance. However, this disturbance did not appear to have reduced wader

numbers in the Dee significantly.

Figure1: Distances (mean values in m and 95% confidence limits) at which flocks of roosting

waders and gulls were recorded to take flight when approached by walking people. Data taken

from Terschelling, July- September 1981 (Smitt and Visser, 1993, data from Tensen & van

Zoest, 1983).



Table1: Approximate values from the diagram figure 1

Species Approximate Distance from

Diagram

Golden Plover

Black-headed Gull

Herring Gull

Oystercatcher

Bar-tailed Godwit

Curlew

Redshank

45

55

59

60

73

95

96

The loss of a roost site due to construction and redevelopment can decrease the numbers of

birds using an area. The redevelopment of an old stone pier in Hartlepool demonstrated this

with maximum numbers of Turnstone (Arenaria interpres), Oystercatcher and Knot

decreasing in the two years since the event despite the creation of an artificial roost (Burton

et al., 1995). This is thought to be as a result of increased disturbance from people and

boats.

3.2.3 HUMAN DISTURBANCE EFFECTS ON THE USE OF MIGRATION STAGING AREAS

Disturbance is a possible factor contributing to long term declines in shorebird abundance at

staging areas that support migrating shorebirds. The results of a study by Pfister et al.,

(1992) show that at high levels of disturbance, impacted species were reduced by up to

50%. Particularly sensitive species in this study were the Knot and the Short-billed

Dowitcher (Limnodromus griseus) whose numbers declined upon analysis of long term

census data in comparison to similar but less disturbed staging areas.

Closed seasons are suggested during migration months to provide refuge areas

3.2.4 SENSITIVITY OF NESTING BIRDS TO HUMAN DISTURBANCE

Shore nesting birds such as the Ringed Plover (Charadrius hiaticula) can be particularly

vulnerable to disturbance by humans. Disturbance has behavioural effects with direct

impacts on reproductive success and survival. These disturbances are from, recreational

activity, dog walkers, unleashed dogs. Effects include:

Reduction in daytime nest attentiveness (Baudains and Lloyd, 2007)

Reduction in time spent incubating eggs (Verhulst et al., 2001)

Complete loss of nests via direct trampling (Liley et al., 2007)



Smaller proportions of collected food being allocated to chicks (Verhulst et al.,

2001)

Energetic costs to chicks engaging in avoidance behaviours (Lord et al., 2001,

1996)

Evidence of habituation to frequent harmless disturbance can be found in White-fronted

Plovers (Charadrius marginatus), which allow a closer approach before leaving the nest and

begin to return to the nest more quickly after a disturbance event (Baudains and Lloyd,

2007)

Human disturbance also effects cliff nesting birds negatively, with negative relationships

existing between human disturbances and nesting success, predicted nesting success

decreases as more people visit the nesting colony (Beale and Monaghan, 2004).

Conservation tools to help prevent disturbance of breeding shorebirds and cliff nesting birds

should be employed:

Adequate set back distances corresponding to the numbers of people present,

(with regards to cliff nesting birds), i.e. larger parties should be kept further away.

Fencing off of areas (with regards to shore nesting birds), are suggested. In the

case of the Ringed Plover Liley et al., (2007) predict that fencing off areas to

humans would increase populations in the study area by 8%.

3.3 Disturbance Responses to Fishing Activities and Bait Digging

Shellfish harvesting using mechanical methods have been shown to cause deleterious

effects on avian fauna feeding in an area. Bird feeding activity will increase initially as

invertebrates are brought to the surface and gulls and waders take advantage of this. In

some species however, the Curlew and Gull spp., numbers subsequently reduced and

remained so for 80 days after the harvesting event, 50 days for the Oystercatcher (Ferns et

al., 2000). Bait digging creates human disturbances when on a small scale and intensive

commercial bait digging removes substantial quantities of larger polychaetes from an area

an important food source for some species of bird such as the Curlew. Negative effects of

bait digging were observed by Shepherd and Boates (1999) on the foraging behaviour of the

Semi-palmated Sandpiper after the first season of digging.

3.4 Disturbance Responses to Boats and Watercraft

Boat disturbance has the potential to affect birds negatively. For the Common Tern (Sterna

hirundo), boats that stay to designated channels caused fewer disturbances to the colony

than those that strayed. Personal watercraft cause the most disturbances with noise levels

from boat motors reaching 80dB(A) at a 15m distance (Clark, 1996) and thus should be

restricted to 100m away from nesting colonies (Burger, 1998).

Knot appear to avoid roosts that have high boat activity within 100m (Burton et al., 1995)



The Black Guillemot (Cepphus grylle) in the Bay of Fundi was looked at in its responses to

boat disturbances. It was suggested that a set back distance of 600m from the shore with a

maximum speed limit of 25km/h would reduce flushing probability to 10% all of the time.

These thresholds can be relevant to other locations and colonial waterbird species (Ronconi

and Cassady-St. Clair, 2002).

Table 2: Distances at which flocks of roosting waders were recorded to take flight when

approached by a kayak or wind surfer (Smitt and Visser, 1993)

From this information it can be deducted that the most sensitive species to the kayak (Knot),

reacted by taking flight at a distance of 262.5m and the most sensitive species to the wind

surfer, (Curlew) reacted by taking flight to the wind surfer at a distance of 400m. Although

the experiment only looks at a few species in only one area, it may be suggested that

kayakers and wind surfers should remain at 263m and 400m from flocks of waterbirds

respectively.

To limit boat disturbance;

Boats should be kept to designated channels 600m from the shore where seabird

colonies breed.

Speeds of boats and personal watercraft should be restricted around roosting and

breeding colonies to 25 km/h.

Boats, kayaks and wind surfers should be kept at least 100m preferably 600m

from roost sites.

3.5 Disturbance Responses to Shooting Activity (Wildfowling & MilitaryActivity)

In a summary of existing data produced by Smitt and Visser (1993) in the Dutch Wadden

Sea, the effects of the Vlieland and Terschelling shooting ranges on waders was noticeably

strong. Roosting Knot and Dunlin left the general area, some returned but were forced away

again by continued shooting. Feeding waders were not as strongly affected but there is

some evidence to suggest that some waders were less tolerant of loud noises than others as

Species Mean Distance Kayak (m) Mean Distance Wind Surfer

(m)

Oystercatcher

Redshank

Knot

Bar-tailed Godwit

Shelduck

Curlew

50

175

262.5

200

200

237.5

125

265

200

237.5

375

400



diversity was higher on non shooting days. Reactions are stronger if sounds are combined

with a visual disturbance. In a literature review by Owen (1993) it was confirmed that there

is no conclusive evidence to suggest that populations on the whole suffered from shooting

disturbance, local distributional shifts have been observed and densities are often higher on

refuge sites, however this may be due to management on such refuges which are usually

reserves. Percival et al., (1998) identify the fact that wildfowling may be restricting current

numbers of wildfowl below those that could be supported by the area (below carrying

capacity) on Lindisfarne National Nature Reserve. From a review looking at experiences

from RSPB reserves by Hirons and Thomas (1993) it is concluded that wildfowling can affect

the local distribution of wildfowl on estuaries, however similar effects of disturbance from

wildfowling on wader populations at either high or low tide have not been convincingly

demonstrated on RSPB reserves.

3.6 Disturbance Responses to Aircraft Noise

Noise effects on shorebirds from aircraft appear little understood. Aircraft operations have

the potential to impact negatively on bird life (Harris, 2005) with major disturbances leading

to;

Health impacts

Breeding performance

Survival of individual birds

Survival of bird colonies

A species example is the negative effect on foraging Knot in the Dutch Wadden Sea, with

large numbers of the birds found to be not present on days where aircraft activity was high.

Aircraft prompted a more severe reaction when the visibility of the birds was reduced.

Habituation to jet fighters is limited. Light aircraft cause very strong disturbances even when

flying above 100m in Knot (Koolhaas et al., 1992). From a review of Wetland Bird Survey

Data, large aircraft were found to be one of the most likely causes of disturbance to coastal

waterbirds (Robinson and Pollitt, 2002)

For Crested Tern (Sterna bergii), the maximum responses observed to simulated aircraft

noise were limited to noises over 85dB(A), these responses are:

Preparing to fly

Flying away

Minimum responses, (head turning scanning behaviour), were observed at all levels of noise

exposure from 65dB(A), whereas the intermediate response of full alert behaviour was

positively correlated with increasing exposure.

Again visual stimulus is likely to be a key component to seabird’s response to noise

disturbance (Brown, 1990).



Observations of aircraft overflights on the Humber have recorded wader flight responses to

fast military jets (effectively arriving over the estuary before their noise), with the same flocks

not exhibiting a flight response to slower training flights by the same type of military aircraft

at the same site, these slower overflights seeing the aircraft arrive over the estuary at the

same time as its noise, with the noise gradually building prior to the aircraft’s arrival (author

pers. obs.).

Similarly, it would appear that a degree of habituation by waterfowl flocks on the estuary

occurs with regular airliner approaches to Humberside Airport, with waterfowl flocks not

responding (at least by a flight response) to airliner approach flights to the airport passing

over the mudflats of Saltend. However, on two occasions, flocks appear to have been

‘spooked’ by the shadow of the airliner on approach when its flight line positioned the

shadow of the plane moving over the mudflat. Finally, differences have been noted in flight

responses to different types of aircraft, although these differences are based on ad hoc

observations rather than detailed analysis. It would appear that light aircraft can elicit a

strong flight response in some species, although habituation has also been noted.

Interestingly, micro lights can also have an impact, and even remote controlled aircraft. On

one occasion, it was observed that the operation of a remote controlled aircraft in the vicinity

of wildfowl had the greatest disturbance effect once the engine had cut, with the remote

controlled aircraft becoming silent whilst still in the air. This immediately led to vigorous

alarm calling and movement of individuals into cover, presumably the loss of noise causing

the aircraft to be perceived as a raptor (author pers. obs.).

Herring Gull (Larus argentatus) do not respond to normal aircraft noise at levels up to 101

dB(A). Supersonic aircraft noises, between the levels of 101 and 116 dB(A), result in a flight

response causing fights and the breaking of eggs upon landing. Again a visual aspect to

response was observed (Burger, 1981).

3.7 Roads and Traffic Noise

Traffic disturbance information for coastal birds is limited. In general, densities of bird

species in woodland and open habitat areas are reduced in sites adjacent to busy roads.

This is related to a reduction in habitat quality from sustained disturbance. Wading birds

assessed on their breeding grounds are negatively affected by traffic noises (Reijnen et al.,

1997).

Numbers of Ringed Plover, Grey Plover, and Curlew are reduced close to roads. Roads and

other manmade landscape features such as railway lines reduce the carrying capacity of

estuaries for these birds (Burton et al., 2002).

3.8 Construction

3.8.1 SALTEND

In a 1999 study by IECS into the disturbance of birds in response to flood defence works at

Saltend on the Humber estuary, a set of disturbance levels for various activities observed

during construction works was set out including effects of noise at different levels.



Different activities are given in order of how severely they affected avian fauna in the area in

the box below.

In a series of reports by IECS to the Saltend Cogeneration Company into the effects of piling

noise on estuarine birds, the monitoring of noise related disturbance was carried out. The

monitoring, conducted in conjunction with noise level attenuation surveys by AVT, (A V

Technology Limited), was initiated in order to assess the degree of disturbance, if any, to the

avifauna from the operation of double hydraulic hammer piling on the site. Modelling of

potential levels across the site suggested that the range of elevated noise would be from 55-

84 dB (A), matching actual observed levels. Effects on avifauna were observed via

observations of flight responses and or behavioural changes.

A significant flight response was observed at the site as a result of a stream venting incident

which saw Dunlin and Ringed Plover put to flight with the noise monitoring logging the event

at between 80-85dB(A). This would appear to concur with the literature that suggests

84dB(A) to be the level at which these responses occur. Differing impact pitch and variable

frequency from the operation of two separate rigs elicited a heads up behavioural response

and the movement down shore by loafing wildfowl. Impact piling carried out at the site

based on personal communication with AVT personnel created noise levels in the region of

70dBAmax which is above the level that would initiate a behavioural response and below the

level that initiates flight responses in most species.

The study concluded that on some occasions it was possible to detect some correlation

between construction activities and measured noise levels. It was thought probable that the

greater the difference between the LAmax (the highest recorded level at the site over the

monitoring period) and the LAeq, equivalent continuous noise level, (an average of the total

sound energy measured over the specified time period) then the greater the possibility for

disturbance to avifauna. Birds were also seen to; in general, accept a wide range of steady

state noise level from between 55dB(A) to 85dB(A) in some cases.

Personnel and plant on mudflat: High

Third Party on mudflat: High

Personnel and plant on seaward toe and face: High to Moderate

Intermittent plant and personnel on crest: High to Moderate

Third Party on bank: High to Moderate

Irregular piling noise (above 70 dB): High to Moderate

Long term plant and personnel on crest: Moderate

Regular piling noise (below 70dB): Moderate

Irregular noise (50-70 dB): Moderate

Regular noise (50-70dB): Moderate to Low

Occasional movement of the crane jib and load above sight-line: Moderate to Low

Noise below 50 dB: Low

Long-term plant only on crest: Low

Activity behind flood bank (inland): Low



Typical noise levels from recorded construction activities are as followed in the box below:

3.8.2 SOUTH HUMBER BANK POWER STATION

Numbers, distribution and disturbance effects on winter, spring and autumn coastal bird

populations along a 1.5 km stretch of coastline near Pyewipe centred on the ABB Power

Generation Ltd’s construction site (South Humber Bank Power Station).

Piling Activity:

Despite consistent periods of piling activity on the pump house construction site on the

landward side of the seawall, birds appeared indifferent to the noise of piling and during

visits in February and March, the numbers and distribution of birds on the mudflats at low

tide was similar during periods of piling and periods without piling. It was therefore

considered that the screening of the mudflats by the seawall was effective in minimising

disturbance effects and birds were in fact recorded arriving to feed during periods of piling

activity.

Upon the extension of construction activity down the seaward slope of the seawall

disturbance effects were noted to a level of disturbance criterion C (Birds disturbed over a

small area, left that area). Birds, however, continued to feed approximately 200m from the

piling operations. April saw flocks remaining at 200m from the construction works, however

it was suggested that the distance at which the birds remained from the activity may have

been exaggerated by the presence of unhabituated migratory species which may be more

susceptible to disturbance effects than wintering birds.

The study went on to suggest that any disturbance caused by piling activity could have also

been attributed to the increased presence of people associated with such activities. Piling

activity on the seaward side only had a disturbance effect on birds.

In summary the monitoring of piling activity recorded the following disturbance impacts:

A January, February, March

C April

These assessments were based on the following disturbance criteria:

Typical LAmax levels during hammer piling 68-70 dB(A)

Typical LAeq levels during hammer piling 55-56 dB(A)

Typical LAmax levels vibratory piling power pack running 51-52 dB(A)

(with no other site activity)

Typical LAmax levels with high site activity 55-60 dB(A)

(cranes, dumper trucks, no hammer piling)

Stream venting from BP site (LA) 80-85 dB(A)



Disturbance Criteria

A No reaction

B Birds disturbed over a small area, resettled after disturbance passed

C Birds disturbed over a small area, left that area

D Birds disturbed over a large area, resettled after disturbance passed

E Birds disturbed over a large area, left that area

Other ABB Site activity:

Other activity was found to have little effect on feeding birds. Flocks on mudflats just 25m

from the structure remained undisturbed by human presence there. Even when disturbance

was caused, effects were minimal with birds retreating only temporarily over short distances.

Third Party Disturbance:

On four occasions the roost by the Middle Drain was disturbed by third party sources. The

disturbance only affected small numbers of birds and was of short duration with birds

resettling either back on the original site or on the seawall upstream of the Middle Drain.

During the repair work along the effluent pipeline, birds remained 100m from the pipeline

when workmen were active; however within 15mins of the workmen departing, a flock of

Dunlin were seen to arrive at the site to feed within 30m of the pipeline. It was also

suggested that Dunlin may have been deterred from using the site during the work as fewer

numbers were recorded than the usual when this work was being undertaken. Numbers

however returned to higher than usual by the week following the activity and thus

disturbance effects were short lived.

Although no serious disturbance events were caused through third party disturbances, this

source had a greater contribution to bird disturbance than other site related activity including

piling.



Table 3: Third party disturbance events on survey days at Pyewipe



Table 3: Cont.

Table 4: Summary of disturbance levels

3.9 Development Case Studies

Developments, their construction and operation, can cause disturbances that significantly

reduce the densities of some species of waterbirds. Case studies are useful to look at,

helping to predict possible effects and impacts from proposed projects.



3.9.1 TIDAL BARRAGE, CARDIFF BAY

Upon the construction of a tidal barrage across the mouth of Cardiff bay; construction work

disturbance accounted for the reduction in densities of 5 species, Green-winged Teal (Anas

carolinensis), Oystercatcher, Dunlin, Curlew and the Redshank on adjacent intertidal

mudflats. As a direct result the carrying capacity for the entire bay was reduced. Feeding

activity is affected negatively by disturbance attributed to construction work. In Cardiff bay,

the Oystercatcher, Dunlin and Redshank demonstrated reduced feeding activity on the

mudflats (Burton et al., 2002). Birds that were displaced from Cardiff bay as a result of

inundation of freshwater following the impoundment of the tidal barrage were found to have

poorer body condition and the Redshank experienced a 44% increase in mortality rate

(Burton et al., 2006).

Tidal barrages in general have detrimental effects on the environment and subsequently on

bird populations; only a portion of the wintering population of birds will be lost on any estuary

where a barrage is built. This is as a result of loss of feeding areas through maintenance

disturbance and direct displacement for the generation arrays. The displacing of wintering

populations could lead to a decline in the population as a whole.

3.9.2 PROPOSED TIDAL BARRAGE, SEVERN

It was originally predicted that the proposed barrage would result in a halving of the area of

mudflats available for feeding, so in effect, bird densities would have to double to remain the

same after the construction of the barrage. This conclusion was investigated and it was

found that with the exception of the Dunlin, for most species the density of invertebrate prey

species required to potentially enable this doubling was well within the range of densities

found at other estuaries however little was known about post barrage invertebrate densities.

Predicting bird densities, however, would depend upon many more factors than invertebrate

density.

3.9.3 MARINA CONSTRUCTION, HARTLEPOOL

Redevelopment of a roost site in conjunction with the construction of a marina caused

increased disturbances from people and boats which subsequently reduced maximum

numbers of Turnstone, Oystercatcher and Knot using a harbour in Hartlepool, Cleveland

(Burton et al., 1995). Creation of replacement roosts, in this case an artificial island go some

way to mitigating the effects of losing an original roost.

3.9.4 PIPELINE CONSTRUCTION, CLONAKILTY BAY

A study into the construction of a pipeline in Clonakilty Bay, West Cork, Ireland in an area of

importance to wintering shorebirds demonstrated that pipeline construction has the potential

to decrease foraging activity in birds (Lewis et al., 2003) during the first few months following

construction leading to detrimental effects on the birds as previously discussed. Impacts can

however be short-lived.



3.9.5 HARBOUR DEVELOPMENT, ANTWERP

Harbour developments can result in species shifts. Long term data on waterbirds near to the

expanding harbour of Antwerp in the Lower Zeescheld revealed a shift in the usage of the

area as it became more important as resting site for herbivorous species such as the

Greylag Goose (Anser anser) and less important as a migration stop over for benthivorous

birds (Van den Burgh et al., 2005).

3.9.6 HUMBER INTERNATIONAL TERMINAL (HIT) CONSTRUCTION, EAST YORKSHIRE, UK

Over six years a team of ornithologists on behalf of ABP marine environmental research

produced a report on the bird usage of an area on the Humber estuary before, during and

after the construction of the HIT development. The project concluded that over the study

period there were no significant trends over time in bird numbers and bird numbers in

general varied over the period of study. The data collected suggested that the HIT

development did not have a significant effect on bird usage in the area. An interesting point

to note would be that the area where construction was occurring became increasingly

important as a roost for the red list species the Black-tailed Godwit (Limosa limosa) with

particularly high usage during February and March. Most disturbance caused by the

development only caused birds to leave over a small area. The monitoring into disturbance

also suggests that the disturbance from walkers, fishermen and flood defence maintenance

have in general been more significant than disturbance from the construction scheme.

3.9.7 WIND FARMS, GENERAL

The main potential hazards/disturbances to birds from wind farms are found to be:

Disturbance leading to displacement, including barriers to movement

Collision mortality

Direct loss of habitat to wind turbines and associated infrastructure (Langston and

Pullan, 2002).

Thus consideration of avian fauna is required upon the construction of wind turbines i.e.

migration passage routes kept clear from obstruction.

3.10 Climate Change

Areas of intertidal mud and saltmarsh are of significant importance to feeding in coastal

birds. These areas are under threat from processes resulting from climate change. Coastal

squeeze is a direct result of sea level rise and coastal development; when sea level rises,

the saltmarsh vegetation which would normally move upward inland, is prevented from doing

so by the presence of sea walls and manmade developments. The marsh area is therefore

squeezed between the rising sea and the coastline so areas are subsequently lost. The loss

of these intertidal areas as important habitat, puts extra pressure on waterbirds that use

them, thus the effects of disturbance on any remaining areas may have a larger effect than

expected as birds have nowhere else to retreat to.



3.11 Managed Realignment Sites (as compensation measures)

The loss of intertidal habitat through industrial development and environmental change, (this

could be via disturbance), is one of the biggest conservation issues for waterbirds in the UK,

the problem being exacerbated by climate change and rising sea level. Managed

realignment, (allowing the sea to penetrate the sea walls creating new intertidal habitat

behind), is a tool that can be used to help compensate for the effects of these losses on

some species of waterbird as they have been proven to develop saltmarsh and biologically

active mudflats over time. Species such as the Dunlin and Redshank are able to use the

sites after just a couple of years with Knot moving in later (4 - 5 years); however the

Oystercatcher requires larger bivalves and so tend not to use these sites (Atkinson et al.,

2004). Managed realigned sites may also be subject to disturbance, for example dog

walkers tend to use the sites and it may be necessary to impose some regulation on these

activities at such sites when species may be particularly sensitive.

3.12 Predictive Models

Models can be used to predict the effects of environmental change such as sea level rise,

daily climatic changes and human disturbances on individual birds and bird populations.

These can then be used for different areas to assess the effects of a change or disturbance

on avifaunal communities. One such model is presented by Durrell et al., (2006) which is

used to predict the quality of habitat for 5 species of overwintering shorebirds in Poole

Harbour. These models can identify conservation issues within an area predicting the

effects of disturbance under different environmental conditions. Individual based models can

also be used to link behavioural responses, (to disturbance), to population consequences

(Stillman et al., 2007). Habitat association models may also be used especially in predicting

whether the creation of mudflats artificially will support the same number of birds as the

areas being lost. In other applications, however, these models tend to give worst case

scenarios.

3.13 Summary of Sensitivity with Recommended Mitigation Measures

Table 5: (next page) Summarises the findings of the main texts of the literature review,

(Appendix 1), in the context of the current review specification.



Author Human Disturbance Construction Boats Aircraft Roads and Traffic

Baudains andLloyd 2007

Daytime nest attentiveness in the white-fronted ploverdecreased with the numbers of people and dogs at bothstudied sites. Habituation was observed at the moredisturbed site. Overall fecundity was higher at the moredisturbed site.

Beale 2007 Optimal management for guillemots is dependent on thenumber of people and their distance to the birds; sites withhigh disturbance should aggregate visitors and sites withlow disturbance should aim for an even distributionthroughout the site.

Beale andMonaghan2004

Turnstones whose condition had been artificially enhancedwere more responsive to human disturbance, flushing atgreater distances, flying further away and increasingscanning behaviours

Blumstein2003

In 64 out of 68 species significant relationships existbetween starting distance and flight initiation distance,species asses risk dynamically and inter-specific differencesin flight initiation distance exist.

Blumstein et al2003

Flight initiation distance is species specific with somespecies more tolerant of disturbance than others.

Blumstein et al2005

Larger species have greater alert distances relative tosmaller species increasing their spatial and temporallimitations on suitable habitat with human disturbance.Sanderlings show 100% response to humans within 30m.

Bolduc andGuillemette2003

Researchers and managers should visit eider colonies aslate as possible and avoid colonies with high densities ofeider egg predators.

Brown 1990 All level of sound between65 dB (A) and 95 dB (A)caused head turning in thecrested tern. Alert responsecorrelated strongly toincreasing exposure withbirds flying away orpreparing to fly at levelsabove 85 dB (A). Visualstimuli play a role.

Burger 1994 Piping plovers will select sites with fewer people than thehabitat as a whole. The time spent devoted to vigilance (notfeeding) is directly related to the number of people near tothem and to the overall use of the habitat by humans. Timedevoted to foraging may be reduced by 40% in the presenceof people. Highlights the importance of habitat diversity.



Burger 1981 Normal colony noises 77dB(A). No effects were notedbetween 88 and 101 dB (A)but supersonic aircraftabove 101 dB (A) elicitedflight resulting in squabblesand broken eggs.

Burger andGochfeld 1991

The number of people within 100m caused variations in timespent foraging in the sanderling with significant negativecorrelations found between the two. Disturbance wasavoided by continuing to feed throughout the night.

Burton et al1995

In the two years since the redevelopmentand loss of a roost-site (replaced with anartificial island), in Hartlepool; maximumnumbers of turnstone, knot andoystercatcher have declined due toincreased boat and human disturbance.

Burton et al2002

Common ringedplover, black belliedplover and curlewnumbers arereduced close toroads

Burton et al2002

Construction work disturbance significantlyreduced the densities of five species, green-winged teal, oystercatcher, dunlin, curlewand redshank on adjacent mudflats and thusthe overall capacity of the bay. Feedingrates were reduced in the oystercatcher,dunlin and redshank on these mudflats.

Burton et al2006

Adult redshank displaced from Cardiff bayexperienced poor body condition and a 44%increase in mortality rate as a result ofinundation by freshwater followingimpoundment by a tidal barrage.

Dias et al 2006 The lack of suitable roosts in the Tagus estuary results inthe underuse of the intertidal flats. Disturbance to existingroosts therefore would have significant effects.

Ferns et al2000

Initially bird number increased after dredging butsignificantly reduced with time



Fitzpatrick et al1998

Arrival times of the oystercatcher and curlew at their lowwater feeding site was delayed as a result of humanpresence and the departures were also significantly earlierfor the redshank and the oystercatcher when disturbed.Significant inter-specific differences were noted in responseto disturbance possibly related to plumage crypsis.

Gill 1996 Fields near to roadswere usedconsiderably lessthan by pink-footedgeese feeding onsugar beet.

Gill et al 2001 Many species avoid human presence but this in the case ofthe black-tailed godwit may not reduce the number ofanimals an area can support

Gill et al 2001 Avoidance behaviour may vary both spatially and temporallydepending on prevailing local conditions. Animals withoutalternative habitat to retreat to may be forced to remaindespite disturbance and its possible effects on survival andreproductive success.

Goss-Custardand Verboven1993

Local levels of disturbance vary with access and habitattype. Feeding rates in oystercatcher can be reduced bydisturbance from 33-50% but overall numbers are notaffected.

Goss-Custardet al 2006

Models used predicted that oystercatcher in the Somme canbe disturbed up to 1.0-1.5 times per hour before their fitnessis reduced in winters with good feeding; in poorer conditionsonly 0.2-0.5 times per hour.

Harris 2005 Bird colonies, (based onbirds in Antarctica), shouldnot be over-flown below 610m above ground level.Landings within 930 mshould be avoided.

Kirby et al1993

Walkers and dogs found to be main disturbance to birds inthe Dee estuary resulting in waders leaving the area and inthe case of the grey plover, knot, bar-tailed godwit anddunlin the estuary altogether.



Kaiser et al2006

Common scoter inLiverpool bay were foundin lowest numbers or wereabsent from areas inwhich anthropogenicdisturbance, (shipping),was relatively intenseeven where prey biomasswas high.

Koolhaas et al1992

Large numbers of knot wererarely found in the DutchWadden Sea on days withhigh aircraft activities, withlight aircraft causing thelargest disturbance. Onaircraft days birds reactedmore strongly to humans.

Langston andPullman 2002

Identified the main potential hazards to birdsfrom wind farms to be: disturbance leadingto displacement including barriers tomovement, collision mortality and direct lossof habitat to wind turbines.

Lewis et al2003

Lower numbers of wading birds thanexpected used the area for foraging in thefirst winter months following the pipelineconstruction. Roosting birds howeverincreased taking advantage of better shelter

Liley et al 2007 The model presented predicted that the fencing off of anarea whilst the common ringed plover were breeding wouldincrease the population by 8%. If human numbers were todouble, a 23% decrease in population is predicted.

Marsden 2000 Human disturbance on flocks of pochard and tufted duck ona Manchester dockland site was most significant in reducingfeeding in the coldest winter periods and unusualdisturbances should be limited.

Mikola et al2004

Broods of common scoter were smaller when disturbedmore frequently relative to those disturbed less frequently.The frequency of gull attacks was 3.5 times greater indisturbed than in undisturbed situations

Mitchell et al2000

The redshank is particularly sensitive to disturbance due tothe long periods of time required feeding in order to meetenergy requirements. Severe weather increases the effectssubstantially.



Pease et al2005

Responses of dabbling ducks to disturbance are dependenton the type of disturbance, species and the distance fromthe disturbance. Ducks were more likely to fly when closerto the disturbance with the green-winged teal and thegadwall showing particular sensitivity.

Percival et al1998

Model predicts that on the Lindisfarne National NatureReserve, factors such as wildfowling may be restrictingnumbers that could be supported by the food supply.

Peters andOtis 2007

Red knot and dowitcheravoided roosts with a highaverage boat activitywithin 100m with thedowitcher tracking boatdisturbance daily.

Pfister et al1992

Implicate disturbance as a potential factor in long termdeclines in shorebird populations at Plymouth Beachreducing its importance as a stopover for migrating birds.Closed seasons are suggested.

Rees et al2005

Feeding activity and alert behaviour in whooper swan isinfluenced by human disturbance accounting for 4.9 % ofthe variance of proportion feeding per hour.

Reijnen et al1997

In general birddensities arestrongly reduced inopen habitatadjacent to busyroads related to areduction in habitatquality.

Roberts 1997 When flocks of sanderling were disturbed by people or dogsthey were more cohesive with more departures being ofwhole flocks in comparison to normal movements.

Robinson andPollitt 2002

The frequency of human disturbance in the UK peaks duringlate summer, 26% of anthropogenic cause. Coastalwaterbirds are most likely to be disturbed by walkers,shooters and large aircraft.

Rogers andSmith 1997

Inter-specific differences in response to disturbance areobserved and a buffer zone of 100m is suggested tominimise disturbance.



Ronconi andCassady-St.Clair 2002

A set back distance of600m from the shore witha speed limit of 25 km/hwould reduce flushing inthe black guillemot to 10%most of the time.Applicable to othercolonial species andlocations.

Stillman andGoss-Custard2002

The behavioural response of oystercatchers is less whenOystercatcher are having more difficulty in surviving hencethe starvation risk from avoidance is greater.

Shepherd andBoates 1999

Negative effects of bait digging on the foraging behaviour ofsemi palmated sandpiper were observed after the firstseason of digging.

Stillman et al2007

Link disturbance behaviour with population changes lookingat individual based models.

Thomas et al2003

Number of people, type of activity, free running dogs andproximity to people significantly reduced the time thatsanderling spent feeding and the distance at which thesanderling moved in response to a disturbance. Dogsshould be leashed and people kept at least 30m from areaswhere shorebirds concentrate.

Van den Burghet al 2005

Observed a species shift in response to anexpanding harbour. The area became moreimportant for resting and winteringherbivorous birds rather than as a migrationstopover for benthivorous birds in the LowerZeeschelde.

Verhulst et al2001

Disturbance to the oystercatcher significantly reduced thetime spent incubating a clutch and the time that the pairspent on the mud. A smaller proportion of food is allocatedto a chick when disturbance is higher demonstratingreduced parental care and thus reproductive success.

Yasue 2005 Semi palmated plover decreased feeding rates when therewere more people on the beach. In least sandpipers effectsof human densities were dependant on flock size and preyavailability.

Yasue 2006 Shorebirds respond more intensely to disturbance when thecost of decreasing foraging rate is lower indicting that thebehavioural response may not reflect effects on fitness



Based on the above review, a series of potential key points have been identified.

The avifaunal community will vary in its sensitivity to disturbances on a seasonal

basis. Sensitivity is greatest in migration periods during the spring and autumn and

measures to reduce disturbance at migration staging areas should be taken, such

measures include closed seasons.

Effects and impacts of disturbance will be increased in hard weather conditions and

thus construction and boating activity should be reduced or ceased at these times.

Redshank are particularly sensitive during these periods

Oystercatcher can tolerate disturbances 0.2 - 0.5 times per hour in poor feeding

conditions, 1.0 - 1.5 times per hour in good feeding conditions above this level,

fitness is reduced.

Roosting birds, especially in areas where there are limited alternative roosting areas

available, will be sensitive to disturbance and in these areas disturbance events

should be restricted at and around high tide as birds begin to roost. Knot are

particularly sensitive to roosting disturbance.

In cases where a roost site is disrupted or lost the creation of artificial roost sites

elsewhere is necessary and effective in mitigating effects caused.

Boating activity around seabird colonies should be restricted with boats kept to

designated channels around a minimum of 100m to preferably 600m from the shore

and watercraft speed restrictions are recommended to be set at 25km/h.

Boating activity around roost sites should be limited to a minimum of 100m to

preferably 600m from the roost especially where there are large numbers of Knot.

The presence of people engaging in both recreational and construction activity on the

mudflats when birds are feeding, particularly in spring and autumn passages and

winter should be restricted as this has a high impact on bird’s fitness.

Birds respond more severely to disturbance from people in greater numbers. Larger

parties or personnel should retain a larger distance from feeding avifauna than

individual persons; 250m recommended (distance set to sensitive species,

Redshank).

Dogs should be leashed at all times and bans imposed during spring and autumn

passages are suggested.

Fencing off of areas where birds are breeding in the summer is suggested.

Ambient construction noise levels should be restricted to below 70dB(A), birds will

habituate to regular noise below this level. Where possible sudden irregular noise

above 50dB(A) should be avoided as this causes maximum disturbance to birds.

However data availability is poor for differing noise sources, receptors and times of

year, and it is suggested that in order to strengthen predictive capacities (and reduce



necessary precautionary factors), a detailed study programme be initiated to provide

a more rigorous scientific basis to thresholds.

Landscape features, such as the presence of roads, other construction projects and

availability of alternative suitable habitats (refuges), in the surrounding environment

need to be considered before any construction activity is carried out as the effects of

disturbance may be increased as a result of such environmental variables.

Cumulative impacts from adjacent construction projects should be considered.

In order to assess available alternative habitat it is necessary to consider cumulative

effects at nearby sites and sites across the estuary due to the high volume of

pressures on the Humber SPA species.

Prior to the commencement of any construction work, a site characterisation should

be carried out whereby documentary data for the avifaunal community is collated and

ground-truthed.

Predictive models may be helpful in the analysis of the possible effects that

disturbance may have on an area.

3.14 Species Approach Distance and Response Schematics

Based on the information gathered from the literature review and given in the summary of

findings, a series of conceptual diagrams have been developed to give an illustrative

overview of the effects of disturbance to waterbirds, from different activities that may arise as

a result of a construction project. Where possible, reactions of individual species have been

given. Here, it is reiterated that birds respond differently to disturbances in different

situations and at different times of year. Thus, the distances given should be used as

guidelines and have been set to unhabituated birds. As a rule, it may be said that distances

may be lengthened in passage periods and shortened where birds have become habituated.

It is therefore recommended that these guidelines should be used in conjunction with a

suitable monitoring programme on any project site.

Disturbance level criteria



Figure 2: Waterbird response to construction disturbance



Figure 3: Waterbird response to third party disturbance on site



Figure 4: Waterbird response to boating activity



4. SENSITIVITY ASSESSMENT FOR THE HUMBER

A sensitivity assessment has been undertaken for the Humber at a basic level, incorporating

physical, biological and anthropogenic parameters.

The approach has been based around the existing WeBS sectors, as these provide a readily

available dataset for avifaunal communities, and are often delineated to specific physical

(topographic) parameters.

A series of anthropogenic activities have been addressed on a sectoral basis where data are

readily available, and the topography of the mudflats is included (e.g. mudflat width),

together with a waterfowl density figure. From these components, a series of index values

have been derived using an Environmental Integrative Indicators (EII) approach and these

have then been used to derive a basic Decision Support System based on EII values.

Such an approach could be developed further, using a more comprehensive suite of EIIs for

the Humber, along the lines of those described in Aubry & Elliott (2006) and Cutts (2008),

and these addressed in conjunction with a more detailed sectoral approach using GIS.

4.1 Species Assemblage Sensitivity Parameters

The assemblage data has been assessed for ‘sensitivity’ based around the WeBS sectors.

For the main species of the assemblage, a series of sensitivity values have been identified.

These include seasonal variations in sensitivity (e.g. wintering, spring and autumn passage

and breeding), for key functions (primarily feeding and roosting), and for the main types of

disturbance stimuli. In addition, values have then been ascribed based on these

parameters, in conjunction with assemblage data for each WeBS sector.

4.1.1 SENSITIVITY OF HUMBER WATERFOWL AT DIFFERENT TIMES OF THE YEAR (BASKET

ASSEMBLAGE)

Response levels are scored as HIGH, MODERATE, MODERATE to LOW

Wintering (October-March)

Redshank (particularly in severe winter weather) Black-tailed godwit (Red Status) Knot (particularly sensitive to disturbance) Turnstone (specific habitat requirements, limited range) Golden Plover (severe winter weather, internationally important numbers, feed

on inland fields) Curlew (large bird, greatest alert distances) Bar-tailed godwit Grey Plover Dunlin Ringed Plover Sanderling Teal Wigeon Shelduck (show habituation) Oystercatcher (show habituation) Lapwing



Spring Passage (late March - April)

Ringed Plover (internationally important numbers) Sanderling (nationally important numbers) Avocet (Schedule 1 Iconic species) Redshank (particularly sensitive to disturbance) Curlew Bar-tailed Godwit Dunlin (less habituated) Grey plover (less habituated) Knot Golden Plover Turnstone Oystercatcher Lapwing

Summer shore breeding (May - June - July)

Avocet (Schedule 1 species) Ringed Plover Oystercatcher Shelduck

Autumn Passage (August- September)

Black-tailed Godwit (Red status) Ringed Plover (internationally important numbers) Redshank Golden Plover (internationally important numbers, use mudflats more for

feeding in this period) Turnstone Curlew Bar-tailed Godwit (species tends to rely on a few sites) Dunlin Grey Plover Knot Sanderling Oystercatcher Lapwing

Whilst a bird’s reaction to disturbance stimuli can be roughly determined by its size, (as a

rule, larger birds have greater alert distances) and plumage, the impacts of these effects

vary among species. Sensitivity may vary for a number of different reasons; birds may be

particularly rare as in the case of the Black-tailed Godwit or may need to spend longer

periods of time feeding to achieve daily intake requirements as in the Redshank. Some

birds may be adversely affected by the weather and others, particularly affected by roosting

disturbance. We can broadly suggest that birds that require longer periods of time for

feeding (small prey in relation to body size) will be more strongly affected by feeding

disturbances.

Winter Assemblage

Species listed in red were chosen because of their particular status, importance on the

Humber, general high level of response and susceptibility to disturbance, as well as

particular sensitivities to severe winter weather. Many overwintering species show

habituation such as the Dunlin and Grey Plover and are thus less sensitive in the winter than

in passage periods, and have therefore been placed in the moderate category. Curlew has

for the moment been placed in the moderate category; however it is noted that this species

may be moved from an amber status, (from RSPB conservation priority categories), to a red



status, and thus would have to be moved to the High category. Species placed in the

moderate to low category have been seen to show strong habituation and are thus less

sensitive to disturbance and its effects.

Spring Assemblage

The assemblage is based on species present in the Humber over the spring passage period.

Species listed in red for the spring passage period have again been placed in this category

as a result of their particular status, importance on the Humber and particular sensitivities to

disturbance. Golden Plover are less important on the Humber during this period and have

thus been placed in the moderate-low category.

Summer Assemblage

Shore breeding species have been placed in this assemblage; those deemed high risk are

rare status species and species that show less habituation.

Autumn Assemblage

Again the assemblage is based on the species present in greatest numbers during the

autumn passage period. Turnstone is present in greater numbers in comparison to spring

and thus has been placed in the Moderate category. Knot are present in fewer numbers than

in the winter and have thus been categorised in the moderate list.

In most cases, it is only on high tides that individual human disturbance (walkers,

wildfowlers, anglers, bird watchers), should be of particular concern at an assemblage level.

However in other cases disturbance remains an issue at low tide. Boating near to large

roosts is a potentially important disturbance factor on the Humber, displacing roosting

Dunlin, Knot and Grey Plover. Aircraft noise, from observation, produces the greatest effect

with most species taking to flight on response to a low flying jet, although as discussed

earlier in text, the level of response will vary between aircraft and species. From observation,

aircraft have the strongest effects putting most birds to flight.

4.1.2 ACTIVITIES IN ORDER OF SEVERITY OF DISTURBANCE ON WATERBIRDS ON THE HUMBER

Response levels are scored as HIGH, HIGH - MODERATE, MODERATE, LOW

Jets (particularly low flying)

Subsonic transport aircraft

Free running dogs within 100m

Irregular construction noises above 70 dB (A)

Other construction activities (personnel on site)

Shooting, (wildfowling and military)

Recreational activity, (walking, running, dogs), within 100m

Boat disturbance within 100m

Regular construction noises 50 - 70 dB (A)

Recreational activity, (walking, running, dogs), outside 100m

Noise below 50 dB (A)



Jets and subsonic aircraft have been placed in the highest category. A number of studies

have pointed towards aircraft being one of the most likely causes of disturbance to coastal

waterbirds. It can also be noted that habituation in birds to jets is limited. From personal

observation it is apparent that aircraft do cause significant disturbance with whole flocks

being put to flight each time a jet passes over. Light aircraft have been shown to cause very

strong disturbances even when flying above 100m. Free running dogs have been shown

from the literature to have a very strong disturbance effect and the presence of free running

dogs has significant negative correlations with the time a bird spends foraging for food. As a

result of this, free running dogs within a 100m of a bird assemblage have been placed in the

highest category of disturbance. In the high to moderate category irregular construction

noises and other construction activity have been placed. In a series of reports by IECS to the

Saltend Congeneration Company, irregular piling noise above 70 dB (A) as well as

personnel on site were seen to cause, high and high to moderate effects. Shooting,

recreational activity and boating activity within 100m as well as regular construction noise

between 50 and 70 dB (A) are categorised as moderate as these activities can have

significant effects on avifauna however are not seen to be as much of an impact as the

previous activities. Recreational activity outside 100m and noise below 50 dB (A) have been

placed in the lowest category as birds have been shown to habituate to low levels of noise

and providing recreational activity is carried out at least 100m from birds will tolerate such

disturbance without effect.



4.1.3 IMPORTANT SECTORS ON THE HUMBER FOR KEY WATERFOWL SPECIES

The following have been derived using the WeBS Sectors and data from the English Nature

Humber Estuary Low Tide Count Programme 2003-2004 which describe spatial and

temporal distributions on a seasonal basis through detailed text, maps and graphs.

Particularly important and well used sites are highlighted in red.

Figure 5: WeBS sectors used for the Humber



Table 6: Location of main species of birds at low tide on the Humber

Species Sensitivity Issue Autumn Winter Spring Summer

Oystercatcher Will habituate but can be more sensitive when

breeding

OSA, OSB, OSC, OSD &

OSE

OSA, OSB, OSC, OSD &

OSE

OSA, OSB, OSC,

OSD & OSE

OSA, OSB,

OSC, OSD

& OSE

Avocet Sensitive to weather, particularly flooding of nests ISD (Read’s Island post

breeding colony)

NA2, ISC, ISD,ISE &

NG

NA2, ISC,

ISD,ISE &

NG

Ringed Plover Sensitive in summer when breeding Whitton Sands, Read’s

Island - ISD, (Whitton ness -

1km east of Winteringham),

Paull to Stone Creek

Intertidal areas - NG. Spurn

Bight, Pyewipe, the

Cleethorpes to Humberston

Fitties, MSC Theddlethorpe

St Helen to North End

Reach OSF.

MSC NG Whole

Estuary

Golden Plover Intertidal flats used for roosting. Nationally important

numbers on the Humber

Middle/outer estuary NF-

NK, MSA-OSF

NF-NK, MSA-OSF

Grey Plover May leave the estuary altogether if roosts are

disturbed

NJ, NK, MSC NJ, NK, MSC, NG, NH NS

Lapwing Use intertidal mudflats for roosting primarily ISB3, NB, ISD, ISE, NA2 NF, NG, NH (Part of), ISH, NB, NC, (ISD, ISE)




ISI, ISJ, ISK

Knot Outer estuary of particular importance, north and

south banks

NJ1, NJ2 NK NJ1, NJ2 NK, MSC , MSF NJ1, NJ2 NK

Dunlin Utilises most intertidal reaches ISD, NG, NJ, NK NF, NK, ISJ, ISK, MSA NJ, NK (Patrington

channel and Spurn)

Black-tailed

Godwit

Red status species ISJJ (Killingholme haven

pits), ISJ (fronting

mudflat)

MSA

Bar-tailed

Godwit

Rely on a few sites only NK (Spurn Bight), MSA

(Pyewipe), MSC

NK (Spurn Bight), MSA

(Pyewipe), MSC, NH/NG

(Stone Creek)

NJ, NK

Curlew Recently moved to a red list species, large birds

therefore greater alert distances

NF, NG, NH, NJ (Saltend -

Skeffling)

NF, NG, NH, NJ. Saltend -

Skeffling (highest

densities: Saltend mudflat,

Cherry Cobb saltmarsh

and west of Welwick

saltmarsh)

NH, NG (Cherry

Cobb and west of

Welwick saltmarsh

Redshank Severely influenced by the weather NK and NG (Intertidal areas

between Saltend and Spurn,

Welwick and Cherry Cobb

Saltmarsh),

NK and NG (Intertidal areas

between Saltend and Spurn,

Welwick and Cherry Cobb

Saltmarsh),

MSA, MSB, MSC

(April Peak)




Turnstone Habituate easily but have a narrow habitat range ISF2 & 3, ISG, ISH, ISI,

MSC

ISF2 & 3, ISG, ISH, ISI ISF2 & 3, ISG, ISH,

ISI (reduced level of

usage)

Sanderling Nationally important numbers on the Humber NK, MSC & OSF NK, MSC & OSF NK, MSC & OSF

Shelduck Humber is important as a wintering site and a late

summer migration stopover, sensitive when

moulting

East NF, NG, NH, NJ, NK,

ISC, ISD, NB

NF, NG, NH, NJ, NK, ISC,

ISD, NB, MSA

ISC, ISD, NB ISC, ISD,

NB

Teal sensitive when moulting ISD, ISC, NB 1234 ISD, ISC, NB 1234, NF, NG NA2

Wigeon sensitive when moulting NB (upper estuary) ISD

(Read’s Island)

NB (upper estuary) ISD

(Read’s Island)

ISB1, ISB2



4.1.4 ROOST SITES ON THE HUMBER (BASED ON DATA FROM, MANDER & CUTTS, 2006)

Waders, species particularly sensitive to roosting disturbance:

Knot Bar-tailed Godwit Grey Plover Dunlin

Wildfowl, Main Species:

Shelduck Teal Wigeon

Figure 6: Position of high tide roosts on the Humber estuary



Table 7: Roosting bird utilisation with WeBS sectors given

High Tide Roost WeBS Sector Species Utilising the Roost

Chalk Bank ISEKnot (40,000)

Dunlin

Oystercatcher

Bar-tailed godwit

Redshank

Grey Plover

Beacon Lagoons NKKnot (40,000)

Dunlin

Oystercatcher

Bar-tailed godwit

Curlew

Grey Plover

Welwick Saltmarsh NH2 a

NH2 c

NH2 b

Knot

Dunlin

Golden Plover

Bar-tailed Godwits

Curlew

Lapwing

Redshank

Oystercatcher

Cherry Cobb Sands NG5

NG6

Dunlin

Curlew

Redshank

Bar-tailed Godwit

Grey Plover

Knot (occasionally)

Paull Holme Strays NG3

NG2

Golden Plover

Lapwing

Black-tailed godwit

Salt End NFGolden Plover

Lapwing

Curlew

Dunlin

Ringed Plover

Teal

Humber Wildfowl Refuge NBWigeon

Teal



High Tide Roost WeBS Sector Species Utilising the Roost

Shelduck

Lapwing

Golden Plover

Howdendyke Lee NA1Lapwing

Golden Plover

Blacktoft NA2Golden Plover

Lapwing

Dunlin

Redshank

Reed’s Island ISDDunlin

Curlew

Redshank

Golden Plover

Lapwing

Black-Tailed Godwit

New Holland Pier fields ISF3Golden Plover

Turnstone

North Killingholme Haven

Pits

ISJBlack-tailed Godwit

Redshank

Cleethorpes/Humberston MSCKnot

Dunlin

Bar-tailed Godwit

Oystercatcher

Grey Plover

Sanderling

Tetney Marshes MSD, MSE1, MSFKnot

Oystercatcher

Golden Plover

Lapwing

Dunlin

Grey Plover



NATURE OF AVIFAUNAL ROOSTING IN THE AREA

BIRDS REGULARLY USE THE AREA AS A ROOSTING SITE +1

KEY SPECIES, SENSITIVE TO ROOSTING DISTURBANCE, +2

USE THE AREA OCCASIONALLY AS A ROOSTING SITE

KEY SPECIES, SENSITIVE TO ROOSTING DISTURBANCE, +3

USE THE AREA REGULARLY AS A ROOSTING SITE

RARE SPECIES USE THE AREA AS A ROOSTING SITE +4

(BLACK-TAILED GODWIT, CURLEW)

4.1.4.1 Roosting Sensitivity Assessment

The following sectoral assessment has been based on a weighting based on assemblage

characteristics and sensitivity values as outlined above.

Table 8: Important WeBS sectors for roosting activity

WeBS Sector where roostingoccurs

Key Species important for Score

ISD Knot (40,000)

Dunlin

Oystercatcher

Bar-tailed Godwit

Black-tailed Godwit

Redshank

Grey Plover

4

ISE Knot (40,000)

Dunlin

Oystercatcher

Bar-tailed godwit

Redshank

Grey Plover

3

NK Knot (40,000)

Dunlin

Oystercatcher

Bar-tailed godwit

Curlew

Grey Plover

3

NH2a Knot

Dunlin

Golden Plover

3





Bar-tailed Godwits

Curlew

Lapwing

Redshank

Oystercatcher

NH2b Knot

Dunlin

Golden Plover

Bar-tailed Godwits

Curlew

Lapwing

Redshank

Oystercatcher

3

NH2c Knot

Dunlin

Golden Plover

Bar-tailed Godwits

Curlew

Lapwing

Redshank

Oystercatcher

3

NG2 Golden Plover

Lapwing

Black-tailed godwit

4

NG3 Golden Plover

Lapwing

Black-tailed godwit

4

NG5 Dunlin

Curlew

Redshank

Bar-tailed Godwit

Grey Plover

Knot (occasionally)

2

NG6 Dunlin

Curlew

Redshank

Bar-tailed Godwit

Grey Plover

Knot (occasionally)

2

NF Golden PloverLapwingCurlewDunlin

Ringed PloverTeal

3

NB Wigeon

Teal

Shelduck

Lapwing

1





Golden Plover

NA1 Lapwing

Golden Plover

1

NA2 Golden Plover

Lapwing

Dunlin

Redshank

3

ISD Dunlin

Curlew

Redshank

Golden Plover

Lapwing

3

ISF3 Golden Plover

Turnstone

1

ISJ Black-tailed Godwit

Redshank

4

MSC Knot

Dunlin

Bar-tailed Godwit

Oystercatcher

Grey Plover

Sanderling

3

MSD Knot

Oystercatcher

Golden Plover

Lapwing

Dunlin

Grey Plover

3

MSE1 Knot

Oystercatcher

Golden Plover

Lapwing

Dunlin

Grey Plover

3

MSF Knot

Oystercatcher

Golden Plover

Lapwing

Dunlin

Grey Plover

3



4.1.4.2 Feeding Sensitivity Assessment

The following sectoral assessment has been based on a weighting based on assemblage

characteristics and sensitivity values as outlined above.

Table 9: Winter feeding scores

WeBS Sector Key Species found within theSector

Score

ITA 1

ITA 2

ITA 3

ITA 4

0

0

0

0

ISA 0

ISB 1

ISB 2

ISB 3

0

0

0

ISC Shelduck, Teal 2

ISD Shelduck,Teal 2

ISE 1

ISE 2

0

0

ISF1 0

ISF 2 Turnstone 3

ISF 3 Turnstone 3

ISG Turnstone 3

ISH Turnstone 3

ISI Turnstone 3

ISJJ Black-tailed Godwit 3

ISJ Dunlin 2

ISK Dunlin 2

NATURE OF AVIFAUNAL FEEDING IN THE AREA

SPECIES HIGHLY SENSITIVE TO FEEDING DISTURBANCE +3

USE THE AREA REGULARY FOR FEEDING

SPECIES MODERATELY SENSITIVE TO FEEDING DISTURBANCE +2

USE THE AREA REGULARLY FOR FEEDING

SPECIES WITH MODERATE TO LOW SENSITIVITY TO FEEDING +1

DISTURBANCE USE THE AREA REGULARLY




Score

MSA Dunlin, Black-tailed Godwit, Bar-tailed

Godwit, Shelduck, Golden Plover

3

MSB Golden Plover 3

MSC Ringed Plover, Grey Plover, Knot, Bar-

tailed Godwit, Sanderling, Golden Plover

3

MSD Golden Plover 3

MSE 1

MSE 2

Golden Plover 3

3

MSF Knot, Golden Plover 3

OSA Oystercatcher 1

OSB Oystercatcher, Golden Plover 3

OSC Oystercatcher, Golden Plover 3

OSD Oystercatcher, Golden Plover 3

OSE Oystercatcher, Golden Plover 3

OSF Sanderling, Golden Plover 3

NA1 a

NA1B

NA1c

0

0

0

NA2 3

NB 1

NB 2

NB 3

NB 4

Shelduck, Teal, Wigeon 2

2

2

2

NC1

NC 2

NC 3

0

0

0

ND 0

NE 0

NF 1

NF 2

Dunlin, Curlew, Shelduck, Teal, Golden

Plover

3

3

NG 1

NG 2

NG 3

NG 4

NG 5

Redshank, Grey Plover, Lapwing, Bar-tailed

Godwit, Curlew, Shelduck, Golden Plover

3

3

3

3

3




Score

NG 6 3

NH1 a

NH1B

NH1c

Grey Plover, Bar-tailed Godwit, Curlew,

Shelduck, Golden Plover

3

3

3

NH2 a

NH2B

NH2c



3

3

3

NJ 1

NJ 2



3

3

NK Grey Plover, Knot, Dunlin, Bar-tailed

Godwit, Redshank, Sanderling, Shelduck,

Golden Plover

3

Table 10: Autumn passage feeding scores

WeBS Sector Key Species found within the Sector Score

ITA 1

ITA 2

ITA 3

ITA 4

0

0

0

0

ISA 0

ISB 1

ISB 2

ISB 3

0

0

0

ISC Shelduck, Teal 1

ISD Avocet, Ringed Plover, Shelduck, Teal 3

ISE 1

ISE 2

0

0

ISF1 0

ISF 2 Turnstone 2

ISF 3 Turnstone 2

ISG Turnstone 2

ISH Turnstone 2

ISI Turnstone 2

ISJJ Black-tailed Godwit 3




ISJ Dunlin, Black-tailed Godwit 3

ISK Dunlin 2

MSA Dunlin, Bar-tailed Godwit, Golden Plover 3

MSB Golden Plover 3

MSC Ringed Plover, Grey Plover, Bar-tailed

Godwit, Turnstone, Sanderling, Golden

Plover

3

MSD Golden Plover 3

MSE 1

MSE 2

Golden Plover 3

3

MSF Golden Plover 3

OSA Oystercatcher, Golden Plover 3

OSB Oystercatcher, Golden Plover 3

OSC Oystercatcher, Golden Plover 3

OSD Oystercatcher, Golden Plover 3

OSE Oystercatcher, Golden Plover 3

OSF Ringed Plover, Sanderling 3

NA1 a

NA1b

NA1c

0

0

0

NA2 0

NB 1

NB 2

NB 3

NB 4

Shelduck, Teal, Wigeon 0

0

0

0

NC1

NC 2

NC 3

0

0

0

ND 0

NE 0

NF 1 Dunlin, Curlew, Teal 2

NF 2 Dunlin, Curlew, Shelduck, Teal 2

NG 1

NG 2

NG 3

NG 4

Ringed Plover, Curlew, Redshank, Shelduck,

Teal

3

3

3

3




NG 5

NG 6

3

3

NH1 a

NH1b

NH1c

Curlew, Shelduck 2

2

2

NH2 a

NH2b

NH2c

Curlew 2

2

2

NJ 1 Knot, Grey Plover, Curlew, Shelduck 2

NJ 2 Knot, Grey Plover, Curlew, Shelduck 2

NK Knot, Dunlin, Bar-tailed Godwit, Redshank,

Sanderling, Shelduck

3

Table 11: Spring passage feeding scores

WeBS Sector Key Species found withinSector

Score

ITA 1

ITA 2

ITA 3

ITA 4

0

0

0

0

ISA 0

ISB 1 Wigeon 0

ISB 2 Wigeon 0

ISB 3 0

ISC Avocet, Shelduck 3

ISD Avocet, Lapwing, Shelduck 3

ISE 1

ISE 2

Avocet, Lapwing 3

3

ISF1 0

ISF 2 Turnstone 1

ISF 3 Turnstone 1

ISG Turnstone 1

ISH Turnstone 1

ISI Turnstone 1

ISJJ 0




Score

ISJ 0

ISK 0

MSA Redshank, Golden Plover 3

MSB Redshank 3

MSC Redshank, Sanderling 3

MSD 0

MSE 1

MSE 2

0

0

MSF 0

OSA Oystercatcher 1

OSB Oystercatcher 1

OSC Oystercatcher 1

OSD Oystercatcher 1

OSE Oystercatcher 1

OSF Sanderling 3

NA1 a

NA1b

NA1c

0

0

0

NA2 Avocet, Teal 3

NB 1

NB 2

NB 3

NB 4

Lapwing, Shelduck 1

1

1

1

NC1

NC 2

NC 3

Lapwing 1

1

1

ND 0

NE 0

NF 1 0

NF 2 0

NG 1

NG 2

NG 3

NG 4

NG 5

Avocet, Ringed Plover, Grey Plover,

Curlew

3

3

3

3

3




Score

NG 6 3

NH1 a

NH1b

NH1c

Curlew 2

2

2

NH2 a

NH2b

NH2c

Curlew 2

2

2

NJ 1 Knot, Dunlin, Bar-tailed Godwit 2

NJ 2 Knot, Dunlin, Bar-tailed Godwit 2

NK Knot, Dunlin, Bar-tailed Godwit,

Sanderling

3

4.2 Sensitivity Assessment Based on Sector Disturbance Parameters

The sensitivity analysis has included a series of indicators based around anthropogenic

activities, in particular, focussing on activities likely to cause disturbance to waterfowl, these

including:

Ports and Other Industrial Activity

Adjacent Roads and Public Rights of Way

Wildfowling, Angling, Bait Digging and Cockle Collecting

The following text describes the parameters and the data-sets used to derive them. It is

emphasised that this approach using Environmental Integrative Indicators (EIIs) is extremely

basic as applied to this document. A more detailed approach using a GIS system has been

applied for the Humber in the context of assessing and comparing ecosystem modification

(Aubrey & Elliott, 2006). Such an approach using a more comprehensive and flexible series

of EIIs to identify waterfowl disturbance and habitat modification issues would be a useful

management tool for the Humber.

Walkers and dogs, bikes, military activities and small boat traffic should also be included;

however the data is not enough to do so and thus further work would be required to achieve

an overall more detailed picture of disturbance.

4.2.1 DATA USED

The following maps including Ordinance Survey maps not shown have been used to derive

basic sectoral information for the EII phase of the programme. It is acknowledged that this

is a simplistic dataset, and that more extensive data will be available from a variety of

sources. However, for the context of this broad brush appraisal, it is considered fit for

purpose.



Figure 7: Point source industrial discharges to the Humber estuary (Source: Elliott & Boyes,

2002).

Figure 8: Coastline modification to the Humber estuary (Source: IECS, 1994).



Examples of data from the Humber Shoreline Management plan are given below.

Again, only a basic analysis has been undertaken for this project, although a more detailed

EII data set could be compiled using a GIS system, with particular relevance and application

if based upon that used for the SMP.

Figure 9.1: Industry - Docks (Hull)

Figure 9.2: Industry - Cement Works



Figure 9.3: Industry - docks (Immingham), power stations and oil refineries.

Figure 9.4: Industry - docks (New Holland).

Construction and Waterfowl: Defining Sensitivity, Response, Impacts and GuidanceHumber INCA


Figure 10.1: East Halton. Wildfowling areas marked in bold red outline.

Figure 10.2: Howden. Wildfowling areas marked in bold red outline

Construction and Waterfowl: Defining Sensitivity, Response, Impacts and GuidanceHumber INCA


Figure 10.3: Skeffling. Wildfowling areas marked in bold red outline

Figure 10.4: Welwick. Wildfowling areas marked in bold red outline



The following sectors have been used for the assessment process; with anthropogenic

activities identified for each sector as appropriate based on the information sources above,

as well as analysis of Microsoft Virtual Earth & Google Maps and information from the

Fishing Activities Humber Management Scheme (NE Sea Fisheries Committee Giles Bartlett

et al 2004).

Table 12: WeBS sectors used in assessment of anthropological assessment

SOUTH BANK NORTH BANK

ITA 1234

ISA

ISB 123

ISC

ISD

ISE 12

ISF123

ISG

ISH

ISI

ISJJ

ISJ

ISK

MSA

MSB

MSC

MSD

MSE 12

MSF

OSA

OSB

OSC

OSD

OSE

OS

NA1 abc

NA2

NB 1234

NC123

ND

NE

NF 12

NG 123456

NH1 abc

NH2 abc

NJ 12

NK



Figure 11.1: Inner estuary, sectors and sub sectors in the Low Tide Count 2003/2004

Figure 11.2: Middle estuary, sectors and sub sectors as used in Low Tide Count 2003/4.



Figure. 11.3: Outer estuary sectors and sub sectors as used in the Low Tide Count 2003/04. All

rights reserved English Nature 100017954 2005.



Based on this analysis, the following associations have been made.

Table 13: Anthropogenic activities

Characteristic WeBS Location

Ports MSB (Grimsby), NE (Hull), NA1 abc (Goole), ISK

(Immingham) NF, ISJJ

Narrow intertidal mudflat (average ≤ .05km) NA1 abc, NB1, NB2, NB3, NB4, NE, NF1, NF2, NG1,

NG2, NH1bc, ISA, ISB1, ISB2, ISD, ISE2, ISF1,

ISF2, ISF3, ISI, ISJ, ISK, ITA1234.

Industrial activity ISD (Ferriby Sluice cement works), ISG (New

Holland dock) ISI ISJJ, ISJ, ISK, MSA, MSB, NF2 &

NE (Saint Andrews Quay)

Close to major A roads ISF1, ND, NE, NF1 & NF2

Wildfowling licensed areas ISH, ISJ (East Halton Skitter) NJ, NH (Patrington

Channel - Easington), NH1abc & NA 1 (refuge also

in NA1 near Reedness) IS, ISE1 MSD, MSE, MSF

Fishing activity:

Bait digging

Recreational angling hotspots

Cockle Gathering

NK, MSB, MSC, OSE, NJ2

Hessle Foreshore (ND), Makro Wall (NE), Hull Dock

Frontage (NF1), Paull Frontage to Thorngumbald

drain (NG2, NG3, NG4), Stoney Creek (NG6,

NH1ab), Hawkins Point, (NH2c) Chalky Point,

Spurn and Kilnsea mudflats (NK), Spurn Point

(NK), Barton-Cleethorpes (ISF2 - MSC)

outer estuary: MSA, MSB, MSC, MSD, MSE, MSF,

OSB, OSC, OSD, OSE, OSF, NH, NJ, NK

Main tourist beaches/areas MSB, MSC (Cleethorpes)

Public rights of way/footpaths:

River Ouse

Inner estuary

Outer estuary

NA1C small areas of fronting saltings

NB1, NC2, NC3, ND, ISE1

ISJ, ISJJ, ISI, ISH small - area of fronting

Saltmarsh. ISG - small area of fronting Saltmarsh,



Characteristic WeBS Location

ISF3 - small area of fronting saltmarsh, ISE2 NG3

NG4 NG5 NG6 (Cherry Cobb Sands), MSA, ISK

(Grimsby-Immingham).

Bird Densities See Table below (English Nature data (low water)

17 Humber species used



Table 14: Sectors with densities greater than birds/ha. *WeBS Sectors with high bird

densities. * Highlighted red have narrow intertidal area.

SEASON

WINTER > 3 Birds/Ha AUTUMN > 3 Birds/Ha SPRING > 3 Birds/Ha

WeBSSectors

ISA

ISB1

ISD

ISI

MSA

MSF

NA1 (c)

NA2

NB1

NB2

NB3

NB4

NF2

NG1

NG2

NG3

NG4

NG5

NG6

NH1 (a)

NJ1

NJ2

NK

ISD

ISJ

ISJJ

MSF

NA1 (a)

NA2

NB2

NB4

NF2

NG4

NG5

NG6

NH1 (a)

NH2 (b)

NH2 (c)

NJ1

NJ2

NK

NB2



Table 15: Sectors with widths below 0.5km

ID AREA (KM2) SECTOR WIDTH

(m)

NA1A 0.424709031 0.650000000

ISE2 0.091108993 70.000000000

NB5 0.101120963 80.000000000

nf1 0.264936204 80.000000000

NA1B 0.312580925 110.000000000

ISB1 0.243350602 120.000000000

NA1C 0.211945164 130.000000000

NG1 0.117075775 150.000000000

ITA1 0.958468765 180.000000000

ISA 0.984774716 200.000000000

ISK 0.755902004 200.000000000

NB1 0.773370486 200.000000000

NE 0.908147749 200.000000000

ISD 1.443909737 220.000000000

ISF3 0.665035485 220.000000000

ISI 0.579243639 230.000000000

NB2 0.683412608 245.000000000

ITA2 0.612976031 260.000000000

ITA4 0.663220148 270.000000000

ISJ 1.017036937 270.000000000

ITA3 0.637616459 290.000000000

ISB2 1.556804581 340.000000000

ISF1 0.707989391 360.000000000

nf2 1.272845899 400.000000000

ISF2 1.405449674 400.000000000

nh1b 0.723888510 400.000000000

NG2 0.347439372 420.000000000

NB3 1.254639277 440.000000000

nh1c 1.654060103 500.000000000

NB4 2.280198324 500.000000000



3 = HIGH DISTURBANCE FACTOR

2 = MODERATE DISTURBANCE FACTOR

1 = MODERATE TO LOW DISTURBANCE FACTOR

AREA CHARACTERISTICS SCORE

PORT ACTIVITY + 3

INDUSTRIAL ACTIVITY + 3

TOURIST ACTIVITY + 3

PUBLIC RIGHTS OF WAY/ FOOTPATHS + 2(Directly adjacent to mudflats, where v small areas saltmarsh exist, indication given)

BAIT DIGGING + 2

RECREATIONAL ANGLING + 2

COCKLE GATHERING + 2

NARROW AREAS OF MUDFLAT, HIGH BIRD DENSITIES + 2

(Autumn & Winter)

NARROW AREAS OF MUDFLAT, LOW BIRD DENSITIES + 1

WILDFOWLING LICENCES + 1

MAJOR ROADS CLOSE BY + 1

For the activities on the Humber shown above, scores have been allocated as a result of

their disturbance effects on birds. The scale is different to that of the response levels in

5.1.2 and wildfowling licensing, whilst recognised as having a significant effect has been

given a lower score when placed in comparison to the other activities. Port activity, industrial

activity and tourist activity have been given the highest scores as we assume here that they

cause the most disruption and disturbance to feeding and roosting birds. Both port and

industrial activities reduce the area of suitable habitat available to birds and also increase

the amount of human activity within an area. Noise levels within these areas may also be

elevated as a result of plant operation and shipping activities, causing further disturbance to

any avifauna in the area. Tourist activity may involve a number of different recreational

activities from walking, walking with a dog, or boating, but it assumes increased human

activity within an area often to quite high levels, with dog walking being of particular concern

with regards to disturbance and thus has been given a high scoring of 3. Public rights of way

here have been given a medium score as we assume that where these are situated close to

the mudflats, the avifauna within an area will be subject to an increased level of human

activity and thus increasing the levels of disturbance in the area. Bait digging, cockle

gathering and recreational angling have been given a medium score of 2. This is due to the

activities involving a person or group of people undertaking actions directly within the

intertidal area, these activities have not been given a higher score despite there apparent

potential for disturbance because birds have been observed to habituate very well to the

presence of bait diggers, cockle gatherers and recreational anglers. In this medium

category, the last characteristic is an area with narrow mudflat and high bird densities. The

score has been allocated because this characteristic increases the effects that a

disturbance event may have on an avifaunal assemblage. We assume that if the area is

small and bird densities are high, the area may be at or close to its carrying capacity and

thus if the assemblage is disturbed then there may be no alternative habitat close by for the

birds to retreat to, possibly causing the birds to leave an area completely. Disturbance

events in these areas may or may not be frequent. Low scores have been allocated to areas



with narrow areas of intertidal mud flat and low bird densities, these areas may only become

a problem when the tide is high and the bird assemblage becomes more congregated.

Areas with wildfowling licences have been given a low score of 1, whilst it is recognised that

wildfowling may pose a threat to the avifauna of an area with some species of waders being

less tolerant of loud noises, the literature is mixed in its opinion. In the Dutch Wadden sea in

a review by Smit and Visser (1993) the effects of shooting ranges on waders was strong,

with some species being forced away, however a literature review produced by Owen (1993)

confirmed that there was no conclusive evidence to suggest that populations on the whole

suffered from shooting disturbance. Densities are often higher in refuge sites but this may

be due to management on such refuge sites which are often reserves. Finally in this last

category roads are considered. There is some evidence to suggest that densities of birds in

open habitat near to adjacent busy roads are reduced, roads and other manmade landscape

features may reduce the carrying capacity of estuaries for affected birds, and thus areas

close to main roads have been given the score of 1.

4.2.2 SECTORAL SENSITIVITY SCORES FOR ANTHROPOGENIC ACTIVITIES

The following tables utilise the above EII scoring methods to provide an overall sectoral EII

for potential anthropogenic disturbance. It is emphasised that this is only in development,

as the ‘disturbance field’ is far more complex and will involve factors such as habituation

which may affect total values. However, it is considered to be of relevance for the current

scale of assessment. Sectors with a relatively high EII disturbance value are shaded in

orange or red for potential severity.



Table16: Sensitivity scores for the Humber based on each sectors potential disturbance

factors, up to a maximum of 12 (Sectors scoring between 7 and 9 shaded orange and 10 to 12

red).

WeBS Sector (South Bank) Score

ITA 1

ITA 2

ITA 3

ITA 4

1

1

1

1

ISA 2

ISB 1

ISB 2

ISB 3

2

1

0

ISC 0

ISD 5

ISE 1

ISE 2

3

3

ISF1

ISF 2

ISF 3

2

3

3

ISG 5

ISH 3

ISI 7

ISJJ 8

ISJ 8

ISK 11

MSA 9

MSB 12

MSC 9

MSD 3

MSE 1

MSE 2

3

3

MSF 3

OSA 2

OSB 2

OSC 2

OSD 2

OSE 4

OSF 2



Table 17: North bank scores

WeBS Sector (North Bank) Score

NA1A

NA1B

NA1C

5

2

5

NA2 0

NB1

NB2

NB3

NB4

4

2

2

2

NC1

NC2

NC3

0

2

2

ND 5

NE 10

NF1

NF2

7

9

NG1

NG2

NG3

NG4

NG5

NG6

2

4

4

4

2

4

NH1A

NH1B

NH1C

7

5

3

NH2A

NH2B

NH2C

3

2

4

NJ1

NJ2

3

4

NK 6

4.3 Individual Waterfowl Sensitivity Values

Finally, individual sensitivity values have been ascribed to species of waterfowl most likely to

be present along the estuary. These values are primarily for waders, as waterfowl metrics

were unavailable, and are based on documentary records of disturbance sensitivity and on

values for weight and required energy intake per day, these being relevant factors which will

determine the overall sensitivity of a species to the effects of disturbance e.g. the general

likelihood of flight (approach tolerances, habituation), as well as potential impacts from

increase energy expenditure and loss of feeding time.



Table 18: Sensitivity table: Main estuary waders

Wader Species

present on the

Humber

Approximate

average

Weight (g)

Average daily

Required energy

intake

(Kj day-1

bird-1

)

Prey Consumed Disturbance Issue Time of year

particularly

sensitive

Curlew Numenius

arquata

883 1408.6 Large polychaetes, Arenicola shellfish

and shrimps.

Large bird, alert distances are high,

easily disturbed, 150m to 100m when

habituated. Require areas of bare arable

fields nearby to retreat from incoming

tide. Large polychaetes removed by bait

digging

Winter

Oystercatcher

Haematopus

ostralegus

541 986.2 Mussels and cockles (Mytilus and

Cerastoderma) on the coast; mainly

worms inland

Shell-fishing activity removes prey

sources. Bright colour will walk away

more frequently. Reduced parental care

observed as a result of disturbance

April -June

(breeding)

Black-tailed Godwit

Limosa limosa

323.8 668.0 Deep invertebrates, insects annelid

worms and molluscs

Larger bird, similar reaction as the

curlew to disturbance. Red list species

(conservation priority)

Winter, spring

and autumn

passages

Bar-tailed Godwit

Limosa lapponica

317.3 677.9 Insects , crustaceans, parts of aquatic

plants

Larger bird, similar reaction as the

curlew to disturbance. Sensitive to

roosting disturbance



Wader Species

present on the

Humber

Approximate

average

Weight (g)

Average daily

Required energy

intake

(Kj day-1

bird-1

)


particularly

sensitive

Avocet

Recurvirostra

avosetta

304.5 648.2 Small crustaceans and insects,

Corophium volutator, Palaemonetes,

Neomysis and Nereis diversicolor.

Require soft mud to feed and Islands to

breed

April-June

(breeding)

Grey Plover

Pluvialis squatarola

248.4 N/A Polychaete worms molluscs and

crustaceans

Roosting disturbance will cause birds to

leave the estuary altogether

Golden Plover

Pluvialis apricaria

211.3 496.6 Beetles, spiders, tipulid larvae,

earthworms and berries. Marine

molluscs and crustaceans recorded

infrequently.

Loss of breeding habitat Winter, spring

and autumn

passages

Lapwing Vanellus

vanellus

199.7 476.6 Earthworms, insects, and larvae,

small fish and occasionally frogs

Weather influenced winter

Knot Calidris canuta 156.5 399.0 bivalves, gastropods and small crabs Particularly sensitive to roosting

disturbance by boats and recreational

activities

Winter, spring

and autumn

passages



Wader Species

present on the

Humber

Approximate

average

Weight (g)

Average daily

Required energy

intake

(Kj day-1

bird-1

)


particularly

sensitive

Redshank Tringa

totanus

128.9 346.4 Insects, small amphipods (Corophium)

small molluscs and small polychaetes

Nereis, Nephtys, Macoma and

Hydrobia.

High daily intake, small prey v sensitive

to disturbances particularly in hard

weather, with relatively high distances

required up to 250m. Require areas of

bare arable fields nearby to retreat from

incoming tide

Winter, hard

weather

conditions

Turnstone Arenaria

interpres

116.5 N/A Invertebrates, molluscs, insects

crustaceans

Roosting, redevelopments, limited

habitat range

winter

Ringed Plover

Charadrius hiaticula

62 203.2 Flies, spiders, marine worms,

crustaceans, molluscs

Similar size and response as dunlin to

disturbance particularly sensitive to

disturbance when nesting

Breeding Mid-

April to late

June.

Sanderling Calidris

alba

61.5 N/A Small marine worms, molluscs and

crustaceans

Nationally important numbers on the

Humber during spring passage

Spring

Dunlin Calidris

alpina

48.4 169.6 Small molluscs small amphipods and

crustaceans, Nereis, Arenicola,

Hydrobia Macoma

More sensitive during spring/autumn

passage, some degree of habituation in

winter. Sensitive to roosting disturbance

Winter, spring

and autumn

passages



4.4 Total Sensitivity Values for the Humber

Based on the derivation of component EII values as detailed above, it has been possible to

derive a total value for waterfowl sensitivity on a sectoral basis (WeBS sectors for the

context of this report). For feeding activity, sensitivity values have been identified for

differing seasons, as usage varies on a seasonal basis. However, for roosting activity, key

sites tend to be used over the main seasons, and as such, a generic sensitivity table has

been used for this activity, although still using a sectoral basis for the analysis. Total

Sensitivity values of 10 or more are given in RED, and are considered to be at greatest risk.

Table 19: Sensitivity values for the feeding assemblage - south bank winter

WeBS Sector PotentialDisturbance

Score

Assemblage Score Total FeedingDisturbance

Score

ITA1

ITA2

ITA3

ITA4

1

1

1

1

0

0

0

0

1

1

1

1

ISA 2 0 2

ISB1

ISB2

ISB3

2

1

0

0

0

0

2

1

0

ISC 0 2 2

ISD 5 2 7

ISE1

ISE2

3

3

0

0

3

3

ISF1

ISF2

ISF3

2

3

3

0

3

3

2

6

6

ISG 5 3 8

ISH 3 3 6

ISI 7 3 10

ISJJ 8 3 11

ISJ 8 2 10

ISK 11 2 13

MSA 9 3 12

MSB 15 3 18

MSC 9 3 12

MSD 3 3 6

MSE1

MSE2

3

3

3

3

6

6

MSF 3 3 6

OSA 2 1 3

OSB 2 3 5

OSC 2 3 5

OSD 2 3 5

OSE 4 3 7

OSF 2 3 5



Table 20: Sensitivity values for the feeding assemblage - north bank winter


Score


Score

NA1A

NA1B

NA1C

5

2

5

0

0

0

5

2

5

NA2 0 0 0

NB1

NB2

NB3

NB4

4

2

2

2

2

2

2

2

6

4

4

4

NC1

NC2

NC3

0

2

2

0

0

0

0

2

2

ND 5 0 5

NE 10 0 10

NF1

NF2

7

9

3

3

10

12

NG1

NG2

NG3

NG4

NG5

NG6

2

4

4

4

2

4

3

3

3

3

3

3

5

7

7

7

5

7

NH1A

NH1B

NH1C

7

5

3

3

3

3

10

8

6

NH2A

NH2B

NH2C

3

2

4

3

3

3

6

5

7

NJ1

NJ2

3

4

3

3

6

7

NK 6 3 9



Table 21: Sensitivity values for the feeding assemblage - south bank autumn


Score


Score

ITA1

ITA2

ITA3

ITA4

1

1

1

1

0

0

0

0

1

1

1

1

ISA 2 0 2

ISB1

ISB2

ISB3

2

1

0

0

0

0

2

1

0

ISC 0 1 1

ISD 5 3 8

ISE1

ISE2

3

3

0

0

3

3

ISF1

ISF2

ISF3

2

3

3

0

2

2

2

5

5

ISG 5 2 7

ISH 3 2 5

ISI 4 2 6

ISJJ 5 3 8

ISJ 8 3 11

ISK 11 2 13

MSA 9 3 12

MSB 12 3 15

MSC 9 3 12

MSD 2 3 5

MSE1

MSE2

2

2

3

3

5

5

MSF 2 3 5

OSA 2 3 5

OSB 2 3 5

OSC 2 3 5

OSD 2 3 5

OSE 4 3 7

OSF 2 3 5



Table 22: Sensitivity values for the feeding assemblage - north bank autumn


Score


Score

NA1A

NA1B

NA1C

5

2

5

0

0

0

5

2

5

NA2 0 0 0

NB1

NB2

NB3

NB4

4

2

2

2

0

0

0

0

4

2

2

2

NC1

NC2

NC3

0

2

2

0

0

0

0

2

2

ND 5 0 5

NE 10 0 10

NF1

NF2

4

6

2

2

6

8

NG1

NG2

NG3

NG4

NG5

NG6

2

4

4

4

2

4

3

3

3

3

3

3

5

7

7

7

5

7

NH1A

NH1B

NH1C

7

5

3

2

2

2

9

7

5

NH2A

NH2B

NH2C

3

2

4

2

2

2

5

4

6

NJ1

NJ2

3

4

2

2

5

6

NK 6 3 9



Table 23: Sensitivity values for the feeding assemblage - south bank spring


Score


Score

ITA1

ITA2

ITA3

ITA4

1

1

1

1

0

0

0

0

1

1

1

1

ISA 2 0 2

ISB1

ISB2

ISB3

2

1

0

0

0

0

2

1

0

ISC 0 3 3

ISD 5 3 8

ISE1

ISE2

3

3

3

3

6

6

ISF1

ISF2

ISF3

2

3

3

0

1

1

2

4

4

ISG 5 1 6

ISH 3 1 4

ISI 4 1 5

ISJJ 5 0 5

ISJ 8 0 8

ISK 11 0 11

MSA 9 3 12

MSB 12 3 15

MSC 9 3 12

MSD 2 0 2

MSE1

MSE2

2

2

0

0

2

2

MSF 2 0 2

OSA 2 1 3

OSB 2 1 3

OSC 2 1 3

OSD 2 1 3

OSE 4 1 5

OSF 2 3 5



Table 24: Sensitivity values for the feeding assemblage - north bank spring


Score


Score

NA1A

NA1B

NA1C

5

2

5

0

0

0

5

2

5

NA2 0 3 3

NB1

NB2

NB3

NB4

4

2

2

2

1

1

1

1

5

3

3

3

NC1

NC2

NC3

0

2

2

1

1

1

1

3

3

ND 5 0 5

NE 10 0 10

NF1

NF2

4

6

0

0

4

6

NG1

NG2

NG3

NG4

NG5

NG6

2

4

4

4

2

4

3

3

3

3

3

3

5

7

7

7

5

7

NH1A

NH1B

NH1C

7

5

3

2

2

2

9

7

5

NH2A

NH2B

NH2C

3

2

4

2

2

2

2

4

6

NJ1

NJ2

3

4

2

2

5

6

NK 6 3 9



Table 25: Sensitivity values for the roosting assemblage - south bank

WeBS Sector PotentialDisturbance Score

Assemblage Score Total RoostingDisturbance

Score

ITA1

ITA2

ITA3

ITA4

1

1

1

1

0

0

0

0

1

1

1

1

ISA 2 0 2

ISB1

ISB2

ISB3

2

1

0

0

1

0

2

1

0

ISC 0 0 0

ISD 5 4 9

ISE1

ISE2

3

3

3

3

6

6

ISF1

ISF2

ISF3

2

3

3

0

0

1

2

3

4

ISG 5 0 5

ISH 3 0 3

ISI 4 0 4

ISJJ 5 4 9

ISJ 8 3 12

ISK 11 0 11

MSA 9 0 9

MSB 12 0 12

MSC 9 3 12

MSD 2 3 5

MSE1

MSE2

2

2

3

0

5

2

MSF 2 3 5

OSA 2 0 2

OSB 2 0 2

OSC 2 0 2

OSD 2 0 2

OSE 4 0 4

OSF 2 0 2



Table 26: Sensitivity values for the roosting assemblage - north bank

WeBS Sector PotentialDisturbance Score

Assemblage Score Total RoostingDisturbance

Score

NA1A

NA1B

NA1C

5

2

5

1

1

1

6

3

6

NA2 0 3 3

NB1

NB2

NB3

NB4

4

2

2

2

1

1

1

1

5

3

3

3

NC1

NC2

NC3

0

2

2

0

0

0

0

2

2

ND 5 0 5

NE 10 0 10

NF1

NF2

4

6

3

3

7

9

NG1

NG2

NG3

NG4

NG5

NG6

2

4

4

4

2

4

0

4

4

0

2

2

2

8

8

4

4

6

NH1A

NH1B

NH1C

7

5

3

0

0

0

7

5

3

NH2A

NH2B

NH2C

3

2

4

3

3

3

6

5

7

NJ1

NJ2

3

4

0

0

3

4

NK 6 3 9

The above tables identify some key areas on the Humber which feature high sensitivity

levels to disturbance. However, it is emphasised that for this programme, the development

and application of such values has been at a basic level. Firstly, the above analysis has

employed a ‘concern’ value at a score of 10 or above, whereas there may be greater

variations within the system that could be picked up by a weighting within this (say from

score 9 to the maximum). Secondly, no attempt has currently been made to extensively

ground-truth the approach and manipulate the EII weightings to provide a more accurate

total score. This would be essential if any detailed application were to be required. Finally,

the data sets used to compile the EII dataset have only a broad scale application, although

more detailed datasets are available. The complexity of such datasets in terms of spatial

and parameter details, would necessitate a more extensive GIS approach to such an

analysis. The future development of the technique used here is discussed in the following

section.



5. SUMMARY & RECOMMENDATIONS

The brief for the current project was broadly to review existing information on the range of

potentially disturbing activities to waterfowl on estuaries, and in particular, identify the levels

of response by waterfowl to a range of stimuli arising from industrial construction work and

operation. The severities of these responses were to be addressed and where possible, an

indication of the current sensitivity of waterfowl assemblages along the Humber was to be

derived.

5.1 Addressing Issues of Concern

From the workshop and brainstorming session hosted by Humber INCA in the autumn of

2007, a series key and sub issues were identified as being useful to know, and based on the

research carried out on this project, summary responses to these issues are included below.

Identify types of disturbance/ Identify which activities cause disturbance

In the summary of findings the main types of disturbances to birds are described with

reference to existing literature and case studies, these main disturbances include:

Human Presence Fishing activities Boating disturbance Shooting disturbance Aircraft noise Roads and Traffic Construction

In the case of construction, case studies are given which outline the effects of specific

developments on avifauna within the area.

Identify sensitive locations

In the section dealing with Humber sensitivities, sensitive locations are defined in two

different ways; the first approach identifies areas along the Humber that have the potential

for disturbing avifauna, i.e. is there a port?, is the area next to a footpath?, is there industrial

activity? The second approach identifies those areas with existing assemblages of avifauna

that currently use the area for feeding or roosting. Scores are allocated to each sector,

(based on the WeBS sectors), using a scoring system that makes use of a basket

assemblage of species with differing sensitivities; the higher the score, the higher the level of

disturbance within the sector.

Identify Seasonal Impacts

In the summary of findings weather conditions and seasonal variations are considered with

examples such as the redshank which demonstrates increased sensitivity to disturbance in

harsh weather conditions in the winter. The basket assemblage is thus altered for each

season, highlighting each species differing sensitivities at different times of the year.



Identify existing solutions

In the final section of the summary of findings, mitigation measures, based on evidence from

the literature review, are suggested to minimise disturbances caused by the types of

disturbance discussed.

Identify gaps in knowledge

The literature review highlights the lack of information regarding the effects of noise on

waterbirds in the UK. The study highlights the need for a more quantitative approach to the

effects of sound at different levels on the behavioural responses of avifauna of different

species, with specific reference to noise generated by construction activity. Habituation is a

recognised phenomenon which could also be looked at in more detail with regards to sound

levels and construction activities.

Identify existing data

The literature review identifies existing data and information regarding bird disturbance.

Identify species characteristics/needs

Species react differently to disturbances, plumage crypsis may be a factor in this as is

discussed in the summary of findings. The literature review also suggests that body size

may be a factor; larger birds will in general react to an approaching disturbance at a greater

distance, this is also touched upon in the summary of findings as is the body size in relation

to the size of prey taken. Birds such as the redshank for example, that take small prey in

relation to body size will have to spend longer feeding and are thus more sensitive to feeding

disturbance. A table was produced with the main species, their average sizes and the prey

taken to give some indication of sensitivities based on body size

Identify spatial/topographical effects

Discussed in the summary of findings is the need for a diversity of habitats, as some bird

species may move between habitats to avoid anthropogenic disturbance.

Identify where birds go when disturbed

The summary of findings briefly discusses how far birds will fly/walk when disturbed. This

distance would appear dependant on the type of disturbance and inter-specific differences,

with some species such as the grey plover, knot, dunlin and bar-tailed godwit often leaving

an estuary completely. The size of the mudflat is thus considered in the Humber sensitivities

sector, as the bigger the mudflat the more area a disturbed bird has to retreat into.

Decide whether the available data can be extrapolated

In the Humber sensitivities section, a scoring system was used to score the different sectors

of the Humber; a high score corresponding to a high level of disturbance. A decision tree

was then constructed incorporating the scoring system allowing for the system, in theory, to

be applied to areas other than the Humber.



Identify whether habituation to different disturbances occurs

The literature review suggests that habituation in some species does appear apparent, this

is less so in the spring and autumn passage periods. This is also discussed in the summary

of findings section for relevant species.

5.2 Summary of Literature Review

The literature review addressed over 100 scientific papers and applied research reports, with

many more initially viewed but then discarded due to lack of relevance. Whilst it is evident

that for some activities, there are good data on likely responses by waterfowl species and/or

assemblages, there remain areas where data are poor. The review identified that:

The avifaunal community will vary in its sensitivity to disturbances on a seasonal

basis.

Sensitivity is greatest in migration periods during the spring and autumn and

measures to reduce disturbance at migration staging areas should be taken.

Effects and impacts of disturbance will be increased in hard weather conditions and

thus construction and boating activity should be reduced or ceased at these times.

Redshank are particularly sensitive during these periods.

Based on information on Oystercatcher tolerance (in order to maintain fitness they

can tolerate disturbances 0.2 - 0.5 times per hour in poor feeding conditions and1.0 -

1.5 times per hour in good feeding conditions), it is evident that individuals feeding on

sub optimal areas or in sub optimal conditions will be more quickly detrimentally

affected by disturbance.

Roosting birds, especially in areas where there are limited alternative roosting areas

available will be sensitive to disturbance and in these areas disturbance events

should be restricted at and around high tide as birds begin to roost.

In cases where a roost site is disrupted or lost, the creation of artificial roost sites

elsewhere maybe effective in mitigating detrimental effects.

Boating activity around seabird colonies should be restricted with boats kept to

designated channels around a minimum of 100 to preferably 600m from the shore.

Boating activity around roost sites should be limited to 100m from the roost.

The presence of people engaging in both recreational and construction activity on the

mudflats when birds are feeding, particularly in spring and autumn passages and

winter should be restricted as this has a high impact on bird’s fitness.

Birds respond more severely to disturbance from people in greater numbers. Larger

parties or personnel should retain a larger distance from avifauna than individual

persons; 100m recommended.



Construction noise levels should be restricted to below 70 dB (A), birds will habituate

to regular noise below this level. Where possible sudden irregular noise above 50 dB

(A) should be avoided as this causes disturbance to birds. However, data are

generally poor.

5.3 Sensitivity Assessment

The project has also involved a basic sensitivity assessment for the Humber. This

assessment has compiled a series of determinands that have a potential to affect sensitivity

levels of waterfowl populations at a sectoral level on the Humber, using the WeBS sectors

as a basis for this.

Sensitivity values have been identified using an Environmental Integrative Indicator (EII)

approach, focussed around the WeBS sectors. This approach has included values for a

series of determinands grouped around the following:

Waterfowl Assemblage (key species and their susceptibility to disturbance).

Waterfowl Function (roosting, feeding, breeding and densities).

Industry and Port Activity

Other Disturbance Stimuli (roads, public access, recreation)

Environmental Factors (mudflat width, topography etc).

From the above, it has been possible to identify potential pinch-points for each determinand

group, and when combined together, they have identified a Total Sensitivity score. It is

emphasised that this is an extremely crude application of the technique, based on some

broad-scale datasets and assumptions, the technique being better suited to application

through GIS. In addition, no attempt has been currently made to ground-truth the relative

impact weightings of the different determinands, nor grade the relative thresholds of the

values against a real-level severity, again components which can be more readily achieved

through GIS analysis.

However, based on the above, the EII approach has identified sectors as having the greatest

potential sensitivity.

South bank:

ISK

MSA

MSB

MSC

North bank:



NE

To a certain extent, the identification of these sectors is expected for the south bank sites, as

they support high numbers of waterfowl including important roosts, whilst are also subject to

substantial anthropogenic activity. However, the north bank sector is of interest given its

relatively low anthropogenic activity and absence of large flocks. As already noted, the

technique as employed here is an extremely blunt tool, and will require substantial set-up

and ground-truthing to provide more targeted information, however, it is considered that

within the current context, the EII approach has proved useful.

5.4 Tool for Management and Decision Making

Using the information from the literature review and the sensitivity assessment, it would be

possible to construct a decision support system for disturbance related issues and

construction requirements. At its most simple, this could use a series of values to identify

sensitivities for an area, and in conjunction with threshold setting, identify the level of

potential ‘issue’ for the development. A very simplistic approach is given below for example,

but with only notional values applied. Note - this should not be used in its current format.

DOES THE AREA HAVE ANYPOTENTIAL DISTURBANCE

FACTORS?

PORT ACTIVITY = SCORE 3INDUSTRIAL ACTIVITY = SCORE 3TOURIST ACTIVITY = SCORE 3PUBLIC RIGHTS OF WAY = SCORE 2BAIT DIGGING = SCORE 2RECREATIONAL ANGLING = SCORE 2COCKLE GATHERING = SCORE 2NARROW MUDFLAT + HIGH DENSITIES = SCORE 2NARROW MUDFLAT + LOW DENSITIES = SCORE 1MAJOR ROADS CLOSE BY = SCORE 1WILDFOWLING LICENCE IN THE AREA = SCORE 1

SCORE = 0

IS THE AREA USEDBY ROOSTING

BIRDS?

BIRDS USE THE AREA REGULARLY AS A ROOSTING SITE= SCORE 1

KEY SPECIES SENSITIVE TO ROOSTING DISTURBANCE USE THEAREA OCCATIONALLY AS A ROOSTING SITE = SCORE 2

KEY SPECIES SENSITIVE TO ROOSTING DISTURBANCE USE THEAREA REGULARLY AS A ROOSTING SITE = SCORE 3

RARE SPECIES USE THE AREA AS A ROOSTING SITE = SCORE 4

SCORE = 0

IS THE AREA USEDBY FEEDING BIRDS?

SPECIES HIGHLY SENSITIVE TO FEEDING DISTURBANCE USE THEAREA REGULARLY FOR FEEDING = SCORE 4

SPECIES MODERATELY SENSITIVE TO FEEDING DISTURBANCEUSE THE AREA REGULARLY FOR FEEDING = SCORE 3

SPECIES WITH MODERATE TO LOW SENSITIVITY TO FEEDINGDISTURBANCE USE THE AREA REGULARLY FOR FEEDING= SCORE 1

SCORE = 0

YES NO

YES NO

YES

YES NOYES

0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25No Likely Impact Possible Low Impact Need for Appropriate Assessment Likely to Be Significant Impact

Score-based Impact Assessment (Notional):

Possible Score-based Decision Support System for Sensitivity AssessmentPlease note that for this document scores and weightings are notional and should not be used.

Figure 12: Management decision tree



A more detailed support system could be employed in conjunction with a GIS expert system.

Such an approach could be used to provide a more quantitative methodology to identifying

the development issues associated with a site, and the likely outcomes of such a

development submission. This would be of use both to developer and consenting

authorities, and would be of value at the beginning of the development process, providing an

‘early warning’ of development locations likely to be of particular sensitivity for a particular

plan or project. Such a system would not only be of value for early scoping of industrial

projects, but also for assessing flood defence options and other activities likely to have an

effect on the EMS assemblage.

The use of EIIs to assess and monitor favourable condition is also a possibility. It is

considered that whilst current assessments use best available data, there are some

components within a condition assessment that could be improved. Current assessments

for waterfowl populations focus on the application of basic maximal values for set periods in

the context of a relatively arbitrary +/- 50% variability. Whilst such an approach can be

argued as being the best use of available data, it potentially misses out on functional

attributes of the system which contribute to the overall ‘health’ of the assemblage.

In particular, the impacts of disturbance to waterfowl populations on estuaries is difficult to

capture within the current metrics applied to favourable condition assessment. Whilst large

scale disturbance effects may lead to a movement of large flocks away from the system, and

this movement might be picked up in the condition assessment in terms of reduction in

maxima, the causal facto of this reduction (in this instance disturbance) cannot be picked up.

It might be argued that such a substantial disturbance event would not be permitted within

the context of existing management controls, however, broader scale, smaller amplitude

impacts may be permitted. Whilst not leading to wide-scale movements by waterfowl from a

system, such smaller scale impacts might lead to changes in feeding activity, roost site take-

up and energy budgets, such changes being potentially profound, but not readily identified to

source. As such, a management system that uses metrics that identify such small-scale

impacts would be of great value in providing swift remedial measures.

The extension of the EII approach as described in earlier sections, to a GIS platform,

combined with some ‘tweaking’ of the input variables and weightings would provide a useful

management tool for the estuarine system. Such an approach would provide an expert

system for assessing likely impacts of industrial (and other) activities on the waterfowl

assemblage of the Humber EMS. In particular, it would allow for sectoral sensitivities to be

characterised in detail, as well as for them to be amended based on new data on

disturbances responses (if and when available) as well as fine-tuning of EII weightings. In

addition, such a platform could react to changing waterfowl assemblage composition,

changing context of local/regional/national population patterns and changing anthropogenic

activity levels (including changes to industrial activity).

When developed in conjunction with a comprehensive GIS system of sectoral assemblages,

sensitivities and current operations, the decision support system could provide additional

value in determining cumulative impact issues and ‘in combination’ pinch-points, and as

such, would provide a useful tool for wider estuarine management. In particular, the use of

EII metrics within a decision support system could allow for prompt action in determining

potentially damaging operations etc. at an early stage, and possibly within a potential spatial



and activity sector. This could include industrial activity, flood defence works, recreational

activity and even environmental events such as storm surges, high run-off periods etc.

Such an approach fits neatly within the requirements for harmonising the management of

river basins (including estuaries and coastal areas) in the context of the Water Framework

Directive, Marine Strategy Directive, Habitats and Species Directives and the Floods

Directive, as well as national instruments such as River Basin Management Planning and the

Humber Flood Risk Management Strategy as well as the Humber Estuary Management

Scheme.



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Appendix 1

APPENDICES

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A1. INTRODUCTION TO LITERATURE REVIEW

The following review highlights and summarises data from a number of scientific papers and

reports, applied research and where appropriate ad hoc observations. The review separates

the data into a series of categories; estuarine, coastal, offshore and terrestrial habitats are

looked at as well as general papers on disturbance; each section, summarising and

explaining existing data. The review looks at examples from the UK, broadening out to

worldwide examples, focusing on waterfowl predominantly.

A1.1 UK and Worldwide Estuaries

A1.1.1 BEHAVIOURAL RESPONSES TO DIRECT HUMAN ACTIVITY

Estuaries provide important habitat for waders and wildfowl, collectively termed waterbirds.

Waterbirds use the estuarine intertidal mudflats, sand flats and salt-marsh for foraging with

others feeding on surrounding marsh and farmland. Estuarine habitats also function as

roosting sites for waterbirds. UK estuaries are of major national and international

importance for waterfowl assemblages and individual species. Disturbance, either by direct

human activity such as walking, running and boating; or by construction activity and related

noise can reduce the function of an estuarine site.

Many manmade features such as roads and footpaths can lead to disturbance of the

avifauna in areas close to these features. Burton et al., (2002) produced a study

investigating the impacts of man-made landscape features on the numbers of estuarine

waterbirds at low tide. The study measured the potential impact of human disturbance, by

relating the numbers of wintering waterbirds to the presence of nearby footpaths, roads,

railroads and towns. Data were taken from the wetland bird survey low tide count survey for

six estuaries and 9 species were looked at. The Shelduck (Tadorna tadorna), Knot (Calidris

canuta), Dunlin (Calidris alpina), Black-tailed Godwit (Limosa limosa), Curlew (Numenius

arquata) and the Redshank (Tringa totanus) were significantly lower where a footpath was

close to a count section whilst numbers of Brent Geese (Branta bernicla) were greater.

Shelduck, Grey Plover (Pluvialis squatarola), Dunlin and Black-tailed Godwit numbers were

reduced close to railroads and the Ringed Plover (Charadrius hiaticula), Grey Plover and

Curlew reduced when close to roads. Ringed Plover numbers appeared greater when close

to towns. The distances at which the birds were affected by disturbance were found to

correspond to existing published data on flight initiation distance. The study provided

evidence that sustained disturbance associated with footpaths, roads and ‘railroads’ reduced

the local habitat quality for waterbirds and subsequently the carrying capacity of estuaries for

these birds.

Table: Mean Flight distances (m) of waterbird species in response to disturbance from walkers

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Table: Buffer distances associated with values used in models

Looking at a UK example; the effects of disturbance on shorebirds on the Exe estuary were

examined by Goss-Custard and Verboven (1993). The study reports that the local level of

disturbance varies according to access and habitat type. Most people occur on sandy areas

where at low water, only a minority of birds of most species feed. By the time most people

arrive, the birds have moved on to their muddy low water feeding areas where disturbance

levels are lower. Disturbance on mussel beds is more intense, the main feeding ground of

the Oystercatcher (Haematopus ostralegus), this disturbance was found to reduce the

feeding rate of Oystercatcher from 33-50%, and this is compensated by feeding where

people are not present. The birds were also found to habituate their behaviour to the

presence of a stationary human; this is achieved by moving to another mussel bed or

adjusting feeding throughout the tidal cycle. Increasing levels of disturbance in the 10-15

years previous to the study were thought to have caused some redistribution in the

Oystercatcher between mussel beds in the study area, with no evidence that numbers have

declined. Numbers of Oystercatcher increased during the study period, in line with the whole

British wintering population.

In general the response of a foraging animal to human disturbance can be considered as a

trade off between the increased perceived predation risk of tolerating the disturbance and

the increased starvation risk of not feeding and avoiding the disturbance. Stillman and

Goss-Custard (2002) use the example of the Oystercatcher to demonstrate that the

response of an overwintering Oystercatcher to disturbance is related to the starvation risk

incurred by avoiding the disturbance. As the winter progresses the birds have to spend

longer feeding to survive, thus having less time to compensate for time lost by avoiding

disturbance. It was found that as the winter progressed the birds would tolerate a closer

approach. These findings have implications for those studies which assume the larger the

behavioural response the more vulnerable the species; the opposite may be true. The report

suggests that the conservation effort needs to be focussed on those species that spend a

high proportion of their time feeding but still have a large response to disturbance.

Another study looking into human disturbance and its effects on foraging behaviour was

undertaken by Verhulst et al., (2001), this time looking into the effects of human disturbance

on foraging and parental care in the Oystercatcher. Two experiments were carried out to

quantify effects of these two activities. In the first experiment, pairs incubating a clutch were

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disturbed on their feeding territories by actively pursuing the birds until they moved out of

their feeding grounds. In the second experiment, foraging pairs of Oystercatcher with chicks

were disturbed by two observers at different distances from the edge of the salt marsh

where the chicks resided. The results from experiment one demonstrated that disturbance

significantly reduced the proportion of time that the clutch was incubated, but also the

proportion of time that the pair spent on the mud flat.

Figure: Effect of human disturbance on foraging and incubation for control, (white circle), and

disturbed days, (filled circle). Data for 3 periods I, 3h 15min-2h before low tide; II, 2h before -

1hr after low tide (disturbance period on disturbed days) and III, 1hr - 3h 30 min after low tide.

In experiment 2, it was found that the total food collected was independent of disturbance,

but smaller proportion of the food collected was allocated to the chicks with increasing

disturbance levels. Both experiments in this study demonstrate the human disturbance of

foraging in breeding Oystercatcher reduced the amount of parental care. The study

concluded by suggesting that this reduced parental care will presumably affect reproductive

success.

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Figure: Effect of human disturbance on foraging success and prey allocation in Oystercatcher

feeding young.

A study by Gill et al., (2001) addressed the effect of human presence on the distribution of

Black-tailed Godwit on coastal areas in eastern England. They identified the prey types

selected by Godwit and related their depletion to different levels and types of human

disturbance at a range of spatial scales. Four categories of human presence were used

powered water craft (PWC), non-powered water craft (NPWC), aircraft (AIR) and walkers,

dog-walkers and cyclists (WALKERS) None of the analyses showed any effect of human

presence on the number of Godwit supported by the food supply at any of the spatial scales

examined. Many species may appear to avoid human presence but this may not reduce the

number of animals supported in an area.

A pilot study was undertaken by Ravenscroft (2005) who investigated the disturbance of

waders and wildfowl on the Stour-Orwell SPA in 2004/2005. These findings have

subsequently been updated by Ravenscroft et al., (2007) - see tables below.

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Table: The frequencies of events and events causing disturbance at the study site over all

tides

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Table: Overall number of events/activities causing disturbance throughout the study

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Table: Numbers of events/activities causing disturbance at high and low tides

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Table: An indication of the relative sensitivity of species to disturbance on the estuaries

through comparison of the presence of species in background and disturbance counts. Also

give is the mean number of each species disturbed per event.

In addition, Ravenscroft et al., (2007) have completed a literature review of bird disturbance

on the Stour-Orwell estuaries (see Appendix 3 of their report).

A1.1.2 WEATHER/CLIMATE

Hughes (2004) reports that saltmarshes are areas of high primary productivity and their

greatest significance for coastal birds is probably as the base of estuarine food webs. In

addition, saltmarshes are of direct importance to birds by providing sites for feeding, nesting

and roosting. Climate change can affect saltmarshes in a number of ways, including through

sea-level rise. When sea-level rises, the marsh vegetation moves upward and inland, sea

walls prevent this movement and to lead to coastal squeeze and loss of marsh area

The weather can have a definite effect on waterbirds especially those that spend more time

feeding. Mitchell et al., (2000) investigated the vulnerability to severe weather and regulation

of body mass Redshank at Teesmouth, northeast England. The report highlights that the

Redshank is vulnerable due to the size of prey taken and its body size meaning it needs to

spend more time feeding than other species and thus is particularly vulnerable to

disturbance in these periods of harsh weather.

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A1.1.3 ROOSTING

In a study into the impact and extent of recreational disturbance to wader roosts on the Dee

estuary, Kirby et al., (1993) found that walkers and dogs were the main source of

disturbance, the potential for disturbance was also noted to have increased and diversified

over the study period. The potential disturbance rates were seen to increase significantly at

the weekend. Actual disturbance effects were mainly caused by dogs. Most types of

disturbance resulted in waders leaving the beach area with Grey Plover, Knot, Dunlin and

Bar-tailed Godwit (Limosa lapponica) most commonly left the estuary altogether when

disturbed. Overall, however, it is noted that the number of waders during the study period

have increased despite the potential for disturbance increasing, the study suggests that this

is a result of a programme of intervention and education by voluntary wardens.

A1.1.4 FISHING AND SHELL FISHING ACTIVITY

Activities such as commercial fishing and shell fishing can effect populations of waterbirds.

Shellfish of marketable size can be harvested much more quickly and efficiently using

mechanical methods such as tractor-powered harvesters and suction dredgers than by

traditional methods. The adverse effects of such machines on non-target organisms need

to be considered carefully before licensing such activities. Ferns et al., (2000) undertook a

study on the Burry Inlet, South Wales to investigate the impact of such activities on

invertebrate and bird populations. The results showed that bird feeding activity increased at

first on the harvested areas, with gulls and waders taking advantage of invertebrates made

available by harvesting. Subsequently, in the area of muddy sand, the level of bird activity

declined compared with control areas. It remained significantly reduced in Curlew and gulls

for more than 80 days after harvesting and in Oystercatcher for more than 50 days. Norris et

al., (1998) discuss changes in the number of Oystercatcher wintering in the Burry Inlet in

relation to the biomass of cockles (Cerastoderma edule) and its commercial exploitation;

stating that population models constructed from estimates of survival and recruitment,

indicated that declines in the availability of cockles and mussels were associated with

changes in Oystercatcher survival between 1970 and 1998 including three periods of mass

mortality and also the recruitment of juvenile birds to both Oystercatcher and Knot

populations. The decline in mussel stocks due to overfishing increased the vulnerability of

the Oystercatcher population to mass mortality episodes in poor cockle years. Norris et al.,

(1998) go on to suggest that the cultivation of mussels in the intertidal area may lead to

better survival in cockle poor years.

A1.1.5 WILDFOWLING

Wildfowling is considered as a potential disturber in a Hirons and Thomas (1993) report on

disturbances on estuaries reviewing experience on an RSPB Nature reserve. Evidence is

presented to suggest that wildfowling affects the local distribution of wildfowl in winter within

estuaries and the report states that the total number of wildfowl using an estuary will

increase with the creation of refuges. Significant effects of wildfowling disturbance on wader

distribution were not seen. From observations on RSPB reserves, other recreational

activities cause substantial disturbance to waterfowl, most reserves however have mitigation

measures such as integrated recreational strategies.

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A1.1.6 AIRCRAFT ACTIVITY

Aircraft activity can have a notable effect on the behaviour of avifauna in an area. Koolhaas

et al., (1992) produced a study into the disturbance of foraging Knot by aircraft in the Dutch

Wadden Sea in August to October. Numbers and behaviour and aircraft activity were

monitored throughout this period. It was found that large numbers of Knot were rarely found

on days with aircraft activity. On aircraft days, Knot flocks showed a greater tendency to fly

up at large distances upon the approach of 2-3 human observers, they were also found to

take to the air more frequently without apparent disturbance on such days. Importantly the

alarm response to jet fighters on foggy days appeared more severe. A limited degree of

habituation to jet fighters was suggested and it was concluded that light airplanes caused

very strong disturbance even when flying above altitudes of 100m.

A1.1.7 CONSTRUCTION DISTURBANCE AND CASE STUDIES

Construction disturbance can be in the form of noise, habitat loss and other construction

related factors and can have considerable effects on the avifauna of the area affected.

Clark (2006) reviewed the main effects that building tidal power barrages would have on the

bird populations using Britain’s estuaries. The changes in the tidal prism that would occur

after a tidal power barrage is built are discussed in the context of their effect on the ecology

of the estuary. Three main issues are discussed; the effect of changes in size and nature of

the intertidal areas of the estuary; effects on saltmarshes; and the displacement of birds at

closure.

Morris and Gisbson produced a study into the conservation experiences of port development

between 1994 and 2005. They conclude with the comments that in England there is now an

extensive experience of issues and the most effective ways of securing environmentally

sustainable development solutions. They also comment that the first examples of habitat

creation via managed realignments are coming to fruition, stating that the realignment sites

at chowderness and Welwick that compensate for Immingham are developing tidally

inundated mudflats.

Of particular interest to the current study, Burton et al., (2002) studied the impact of

disturbance from construction work around Cardiff Bay, south Wales, on the densities and

feeding behaviour of seven waterbird species over an 11-year period. It was reported that

construction of a barrage across the mouth of the bay has subsequently resulted in its

impoundment; other major works included the construction of a bridge carrying a divided

highway. Construction work disturbance significantly reduced the densities of five species -

Green-winged Teal (Anas crecca), Oystercatcher, Dunlin, Curlew, and Redshank - on

adjacent intertidal mudflats, and thus the overall carrying capacity of the bay. Construction

work also reduced the feeding activity of Oystercatcher, Dunlin, and Redshank on these

mudflats. The possible impact of the loss of birds from these mudflats upon the populations

that the bay supported is discussed. Evidence from other local studies suggests that the

displacement of common redshank from these mudflats did not contribute to a decline in this

species.

A useful case study to look at is the effect of flood defence works at Saltend on

assemblages of birds. IECS (2007) report on the avifaunal disturbance associated with flood

defence works at Saltend. The response of avifauna at Saltend to construction activities

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depended in part upon the type of disturbance. The ingress of personnel onto the mudflat

created the greatest disturbance, with long term operation of plant on the bank without

external personnel having the least effect. Broad assumptions based on observation of the

flood-defence upgrade work were made and the main impacts of construction were given:

The report summarises that the degree of disturbance on the avifauna of a site will depend

upon a number of variables including:

Type of disturbance

Avifaunal community present

Avifaunal function/activity

Extent and topography of site

Time of year

Level of third party disturbance

Weather conditions

Another case study is presented by Lewis et al., (2003) assessing the recovery of a benthic

invertebrate community one year after a pipeline construction at Clonakilty Bay, West Cork,

Ireland. In addition, as the site is important for wintering wading birds, the study investigated

the responses of estuarine bird species in the 18 months following the pipeline construction,

including two winter periods. The study found that lower numbers, than the calculated

expected number, of wading birds foraged within the impacted area during nearly all months

of the first winter following the pipeline construction. The impacted area, however, held

greater numbers of diurnally roosting birds than expected, the birds apparently taking

advantage of the roughened sediment for shelter or to aid camouflage. The implications of

habitat loss for foraging birds are therefore discussed, even when the impact, as in this

study, was relatively limited and short term.

Personnel and plant on mudflat: High

Third Party on mudflat: High

Personnel and plant on seaward toe and face: High to Moderate

Intermittent plant and personnel on crest: High to Moderate

Third Party on bank: High-Moderate

Irregular piling noise (above 70 dB): High to Moderate

Long term plant and personnel on crest: Moderate

Regular piling noise (below 70dB): Moderate

Irregular noise (50-70 dB): Moderate

Regular noise (50-70dB): Moderate to Low

Occasional movement of the crane jib and load above sight-line: Moderate-Low

Noise below 50 dB: Low

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Van den Burgh et al., (2005) present a case study examining long term changes in waterbird

communities near to an expanding harbour in the Lower Zeeschelde. The study uses long

term data sets, from 1982-1998, on waterbirds in the intertidal areas near to the port of

Antwerp; situated in the transition between the brackish and freshwater tidal part. The study

attempts to assess the impact of two container terminals, constructed during the covered

period. Overall the study found that the abundance of waterbirds in the study area showed

no significant trends. The trophic composition of the bird populations showed major shifts.

Results revealed that the area became more important as a wintering and resting site for

herbivores such as the Greylag Goose (Anser anser) and Wigeon (Anas penelope) whilst its

importance as a feeding ground and stopover site for migrating benthivorous birds became

relatively less important, particularly the right bank. The study found no direct impacts from

the container terminal construction.

A1.1.8 MODELS

Models can be used to forecast population changes in avifauna in response to varying

environmental factors, like sea level rise for example.

In a study conducted by Dias et al., 2006, the distance of suitable high tide roosting areas

with respect to foraging areas for the Dunlin were examined using a model, as well as

subsequent implications for the management of estuarine wetlands. The study was done in

the Tagus estuary in Portugal and the study focussed on roosts that were currently used by

large numbers of shorebirds figure below. The results of applying a model to the Tagus

show that the lack of suitable roosts in the Tagus Estuary explains why the intertidal flats in

the North West of the estuary are underused by shorebirds. The study suggests that

creating an artificial roost in an old drained wetland area may offset the lack of natural

roosts. This study would indicate that direct anthropogenic disturbance in high tide roosting

areas will have knock on effects for the usage of the estuary as a whole by shorebirds such

as Dunlin.

Durrell et al., (2005) present a model to predict the efficacy of proposed mitigation areas for

shorebirds, a case study on the Seine estuary in France is used. The behaviour-based

model was used to explore the effect of an extension of the port at Le Harve. The

disturbance of feeding birds and roosting both day and night had a significant effect on the

mortality and body condition of all three species studied, Curlew, Dunlin and Oystercatcher.

In the day time, significant effects were only noted in the Dunlin. The model predicted that

the creation of a buffer zone to mitigate disturbance was effective. The creation of new

intertidal area to compensate for loss of habitat was effective but was not sufficient to

mitigate roost disturbance in the Oystercatcher.

In a further paper by Durrell et al., (2006), a model is produced that predicts the effect of

environmental change on shorebirds based on a case study on Poole Harbour. The model

is an individual based model MORPH and in this case is used to predict the quality of Poole

Harbour for five overwintering shorebirds: Dunlin, Redshank, Black-tailed Godwit,

Oystercatcher and the Curlew. The study focuses on the effect of environmental change in

terms of daily climatic changes such as mean daily temperature, increased risk of flooding

and sea level rise. Disturbers were considered to be any human source of disturbance which

would affect the birds, causing them to stop feeding and fly away incurring higher energy

costs. The data used in this particular case were estimations based on data for the Somme

Estuary, northern France. Higher disturber frequencies were given to the patches located

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near to the mouth of the Harbour which are sandy and attract bait diggers. Terrestrial

habitats were also given higher disturber frequencies. The results demonstrated that the

Dunlin had the highest prey densities and thus were the least likely to be affected by

reductions in food supply lower temperatures and loss of terrestrial habitats. Black-tailed

Godwit and Curlew were the most likely to be affected by reductions in food supply lower

temperatures and loss of terrestrial habitats. All 5 species were seriously affected by sea

level rise simulation. Conservation issues arising for Poole Harbour were the lack or larger

sized polychaete worms, the importance of managing surrounding terrestrial habitats and the

effect of sea level on the length of time for which intertidal food supplies are available.

Stillman et al., (2007) state that assessments of whether disturbance is having a deleterious

effect on populations have often measured behavioural responses to disturbance and

assumed that populations with a larger behavioural response are more susceptible to

disturbance. However, there is no guarantee that the behavioural response to disturbance is

related to the population consequence, measured in terms of decreased reproduction or

increased mortality. Individual-based models, consisting of fitness-maximizing individuals,

are one means of linking the behavioural responses to disturbance to population

consequences. This paper reviews how individual-based models have been used to predict

the effect of disturbance on populations of shorebirds and wildfowl at several European

sites, and shows how these models could be improved in the future by incorporating a range

of alternative responses to disturbance. However, Stillman et al., (2007) recognise that

disturbance is just one form of environmental change and coastal birds share characteristics

with many other species, and individual-based models can be applied to a much wider range

of species and environmental issues.

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Figure: Shorebird and wildfowl systems for which individual based models have been

developed, the figure describes the environmental issue addressed in each system and

highlights in grey shading those systems in which the effect of human disturbance has been

incorporated (Stillman et al., 2007)

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Figure: The percentage of an initial autumn population of 1500 Oystercatcher on the Exe

estuary that were predicted to die from starvation over the winter, in relation to the restrictions

imposed by disturbance from people (Stillman et al., 2007)

The major questions identified by Stillman (2007) for future research are:

1 what determines patterns of human disturbance;

2 how can we determine population-level responses to disturbance;

3 are there general rules for predicting how important disturbance will be;

4 how important are disturbance-derived ecological traps;

5 what is the interaction between predation and disturbance;

6 when does habituation occur;

7 how do physiological responses to disturbance affect population size;

8 what is the evidence for changes in access impacting upon populations;

9 what are the positive consequences of access to the countryside;

10 how important is habitat-specific disturbance;

11 which measures reduce human impact; and

12 how can large-scale planning minimize the impact of disturbance?

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To assess the long-term effects of human disturbance on birds, ways of predicting its

impacts on individual fitness and population size must be found.

West et al., (2002) use a behaviour-based model to predict the impact of human disturbance

on Oystercatcher on their intertidal feeding grounds in the Exe estuary in winter. The model

predicted that, for the same overall area disturbed, numerous small disturbances would be

more damaging than fewer, larger disturbances. When the time and energy costs arising

from disturbance were included, disturbance could be more damaging than permanent

habitat loss. Preventing disturbance during late winter, when feeding conditions were

harder, practically eliminated its predicted population consequences. Although disturbance

can cause increased mortality, it was not predicted to do so at the levels currently occurring

in the Exe estuary.

Table: Types of mobile unpredictable human disturbance occurring commonly on estuaries

(West et al., 2002)

A1.1.9 MANAGED REALIGNMENT AND COLONISATION

In some cases, loss of habitat caused by construction and/or sea level rise is offset by

creating new intertidal habitat; these managed realigned sites may be useful habitat for

waterbirds. Atkinson et al., (2004) review the colonisation of the Tollesbury and Orplands

managed realignment sites on the Blackwater Estuary in Essex by birds during a five year

period following their breach. See table below

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Table: Bird usage at Tollesbury managed realigned site

Lourenco et al., (2005) measured the abundance of seven wader species at five distance

classes from drainage channels, and analysed the variation in peck rates, step rates, turning

rates and success rates. In addition the density of macroinvertebrate prey and the sediment

physical–chemical characteristics at different distances from the channels were measured.

All wader species occurred at higher densities near the channels. In the study area 44% of

the birds fed on just 12% of the available surface, less than 5m away from drainage

channels. Wader foraging behaviour also suggests a greater feeding effort near the

channels. While the characteristics of the sediments did not change significantly with

distance from channels, prey abundance corresponded closely with wader abundance,

suggesting that the small scale distribution of birds on the tidal flats may be related to the

presence of their prey. This study showed that the areas around drainage channels are

particularly important feeding sites for waders foraging on tidal flats. Consequently,

managers of estuarine wetlands should strive to preserve or improve channel networks.

This can be achieved by (i) preserving saltmarshes and saltpans adjacent to tidal flats, (ii)

minimising the reclamation of upshore flats and (iii) avoiding embankments and

canalisations of inland water flows that reduce the number of water entry points onto tidal flat

A1.2 UK and Worldwide Coasts

Coasts, as estuaries, provide vital habitat for both waders and wildfowl in the UK and on a

larger scale worldwide. Many coasts also provide habitat for nesting seabird colonies. As

with estuaries, a number of different activities including construction, act as disturbers to

avifaunal assemblages and species.

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A1.2.1 BEHAVIOURAL RESPONSES TO DIRECT HUMAN ACTIVITY

Birds react differently to disturbance; disturbance response if often thought of as a species

specific trait. In the study performed by Blumstein et al., (2003) the critical assumption that

flight initiation distance, (the distance at which a bird can be approached before it flies off), is

a species specific trait is tested. The assumption was tested for developing buffer zones by

experimentally approaching eight species of shorebirds, (foraging or at rest initially), found at

six sites around Botany Bay, 15km south of Sydney Australia. The site encompasses a wide

range of human impacted areas, all of which are important overwintering habitat for

migrating shorebirds. The results of the study found that birds either flew or walked away

from the disturbance and it was concluded that both species and site influenced the distance

birds flew away from an approaching human. An important finding in this study was that

there was no interaction between site and species, “flighty” species were always flighty,

whilst tolerant species were consistently tolerant, this would indicate that the FID is species

specific and managers using data for a given species as guidelines are ok to do so.

Bolduc & Guillemette (2003) report that Eider (Somateria mollissima) colonies often are

subjected to human visitors, such as down collectors, recreationists and researchers,

however, the effects of frequency and timing of disturbance, and the abundance of nearby

avian predators on eider nesting success have been studied only partly. They used three

experimental treatments and six eider colonies over 3 years (1993–1995) at the Mingan

Archipelago National Park Reserve, Québec, Canada to test the effects of these factors on

Eider nesting success, while controlling results for associated gull nest density. Treatments

consisted of (1) high frequency visits (once every 3 days) starting early in the incubation

period (HFE), (2) low frequency visits (once every 15 days) starting early in the incubation

period (LFE), and (3) high frequency visits starting late in the incubation period (HFL).

Analysis of covariance indicated that both disturbance treatments and associated gull nest

density had a significant effect on Eider nesting success probability. Nesting success

probabilities were similar for eiders under HFE and LFE treatments (means=0.317_0.166

[SE] and 0.434_0.172 respectively), indicating that changes in frequency of visits had little

impact on nesting success. In contrast, timing of visits had a major influence on nesting

success, as the HFL treatment resulted in a significant higher nesting success probability

(mean=0.981_0.191) than the HFE treatment. Most nest failures occurred after the first visit

in all treatments, although the impact of the first visit was lowest in the HFL treatment.

Bolduc and Guillemette (2003) concluded that researchers and wildlife managers should visit

Eider colonies as late as possible, and avoid visiting colonies associated with high densities

of Eider egg predators.

Beale & Monaghan (2004) tested the link between individual state and responsiveness by

manipulating condition via the provision of supplementary food for Turnstone (Arenaria

interpres) on rocky shores in East Lothian, Scotland. Birds at one site were fed 450 g of

mealworms at low tide every day for 3 days while birds at another site acted as a control.

On the fourth day, using a standardised disturbance protocol, flush distances, flight lengths

and the amount of time between predator scans were recorded for birds in both flocks.

Flush distance was determined after the birds had flown by pacing from the point that the

observer had reached when the birds flew to the location where the nearest flushed bird had

been. Flight distance was determined by pacing from this point to the site where the flock

first landed, once the birds moved away from the area of their own accord. For each bird

present the length of two interscan intervals (the length of time the bird spends with its head

down feeding between scans) for predators was measured, and thus the average for each

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bird could be calculated. After a break of 3 days, the treatments were then swapped

between sites and the procedure repeated for a total of six trials. Birds whose condition had

been enhanced showed greater responsiveness to standardized human disturbance, flying

away at greater distances from the observer, scanning more frequently for predators and

flying further when flushed. These findings suggest that current management of the impact

of human disturbance may be based on inaccurate assessments of vulnerability.

The effects of recreational disturbance on the foraging behaviour of waders on a rocky

beach were observed by Fitzpatrick et al., (1998). Three species of wading birds were

looked at, the Oystercatcher, Curlew and the Redshank. The study reports that these birds

reacted in a number of different ways to human disturbance. The results regarding beach

usage showed that the birds arrived between 3 and 4 hours before low water and the arrival

times for the Oystercatcher and the Curlew were significantly later, (relative to low water),

when there were people on the beach. When people were active, Redshank did not arrive

until considerably later. Departure occurred between 3 and 4 hours after low water. The

departures of the Redshank and the Oystercatcher were significantly earlier when disturbed.

The departure of the Curlew did not differ with disturbance in this study. Vigilance (scan

rates), was seen to increase with the strength of human activity and the birds were more

vigilant in the higher shore zones, figure below but no corresponding decrease in food

searching (peck rate) was found.

Figure: Scan rates of a) Oystercatcher, b) Curlew and c) Redshank according to zone of beach

occupied by the bird and the type of human activity (Fitzpatrick et al.,1998)

A realistic estimate of the average disturbance rate for the beach was thought to be 3-4

disturbances per hour. All the species were found to respond to disturbance but there were

significant inter-specific differences in the frequency of these responses. The Oystercatcher

walked away more frequently, but stopped feeding and flew away from sites less frequently.

The Curlew stopped feeding more frequently and walked or flew to another part of the beach

less frequently than expected. Redshank also walked away less frequently than expected

figure below. This difference was suggested to be related to plumage crypsis, i.e. the

Curlew and Redshank are better camouflaged and it would be less of a risk for them to keep

still.

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Figure: Occurrence of each type of behavioural response by waders to disturbance. The

asterisks show expected values if all species reacted in the same way (Fitzpatrick et al.,1998)

Flight distances for all species were very low. The waders in this study were found to cope

with disturbance by habituation to continued but harmless human disturbance and presence.

The birds in this study continued to feed in the presence of humans but were noted to adjust

their vigilance according to the levels of disturbance that they were subject to. Fitzpatrick et

al suggest that this may be an important method of reducing the reduction in food intake

induced by human disturbance to a level that can be easily compensated for under normal

undisturbed foraging behaviour. It should be also noted that this study was performed in the

summer months and the different feeding conditions in the winter may mean that the waders

ability to compensate for these losses due to disturbance is altered consequently the waders

response to disturbance may change in the winter months.

Kaiser et al., (2006) investigated the distribution and behaviour of Common Scoter (Melanitta

nigra) in Liverpool Bay with respect to prey resources and environmental parameters. The

highest numbers of Common Scoter coincided with sites that had a high abundance and

biomass of bivalve prey species. There was strong evidence that the maximum observed

biomass of bivalves occurred at a mean depth of c. 14 m off the Lancashire coast and at c. 8

m off the north Wales coast. This coincided well with the distribution of Common Scoter at

Shell Flat, but less well with the distribution of birds off North Wales. Common Scoters were

observed in lowest numbers or were absent from areas in which anthropogenic disturbance

(shipping activity) was relatively intense, even when these areas held a high prey biomass.

Commercial fishing activities did not appear to contribute to this disturbance.

Mikola et al., (2004) studied the consequences of human disturbance and gull predation on

brood survival of Velvet Scoter (Melanitta fusca) in the Archipelago of South-West Finland in

1990 and 1991. Each brood was exposed to disturbance by boats on average 8.5 times a

day in 1990 and 3.5 times a day in 1991. Disturbance lengthened the swimming distances

of ducklings and reduced the time used for feeding. Broods disturbed more frequently than

average were smaller than those disturbed less frequently. At least 60% of ducklings died

before the age of three weeks. The common predators of ducklings in the study area are

the Herring Gull (Larus argentatus) and the Great Black-backed Gull (Larus marinus). The

daily predation rate by gulls on Velvet Scoter ducklings was 4.7%, which means that 56% of

ducklings are caught by gulls during the first three weeks. The frequency of gull attacks was

3.5 times higher in disturbed than in undisturbed situations.

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In a study on the effects of human presence, flock size and prey density on shorebird

foraging rates, Yasue (2005) determined whether people caused shorebirds to reduce

feeding rates at a stopover site in coastal British Columbia, Canada. It was found that Semi-

palmated Plover (Charadrius semipalmatus) decreased feeding rates when there were more

people on the beach. For Least Sandpiper (Calidris minutilla) the effect of human densities

on feeding rates depended on flock size and amphipod availability. Overall the study

demonstrated the importance of measuring subtle behavioural changes in foraging rates

along with key ecological variables in order to assess the true impact of human disturbance

on migratory shorebirds. In a later study by Yasue (2006) investigated the effect of

environmental factors and spatial scale influence on shorebirds responses to human

disturbance. The extent of a shorebirds response to a human disturbance depends on the

associated energetic or predation risk costs effected by environmental variables at special

and temporal scales. The results of the study suggested that people did not displace the

shorebirds, instead, shorebirds were found to select areas further from forest cover that may

have a lower predation risk. The time taken for birds to resume feeding after a human

disturbance was greater in the morning and in areas of low prey availability. This suggests

that shorebirds respond more to disturbance when the foraging cost is lower indicating that

behavioural responses may not reflect potential fitness costs to human disturbance.

Figure: Total prey (a) and time of day (b) plotted against time taken to resume feeding (Yasue

2005)

Norris et al., (2004) discusses past declines and possible future impacts of climate change

on coastal waterbird populations in the UK.

Flights from foraging flocks of Sanderling (Calidris alba) were observed at Redcar, northeast

England, in order to investigate how individual decisions to fly related to the behaviour of

other flock members Roberts (1997). Flights of Sanderling tended to be either of all birds in

the flock on the ground, or of single birds or groups representing only a small proportion of

the foraging flock. The latter accounted for the majority of movement events but after

weighting by flock size the former accounted for the majority of bird movements. As flock

size increased, the number of birds that flew without the whole flock taking flight increased.

Thus, as flock size increased, it took more individual departures before the whole flock took

flight. When flocks were disturbed by people or dogs, they were more cohesive, with more

departures being of whole flocks.

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In a study into the effects of human disturbance influencing the diurnal and nocturnal

foraging of Sanderling, Burger and Gochfeld (1991) examined foraging behaviour of

Sanderling in the winter of 1986, 1988 and 1990. The models used in this study suggested

that the number of people within 100m of the foraging Sanderling was enough to cause

variations in time spent foraging. In all three years there were significant negative

correlations between time devoted to feeding and the time Sanderling flew or ran because of

people and the number of people within 10 and 100 m of the feeding Sanderling. From 1986

to 1990, the number of people within 100m of a foraging Sanderling rose dramatically with a

subsequent decrease in foraging time per minute observed. Sanderling were found to

continue feeding through dusk into the night when time devoted to human disturbance

avoidance was less with time devoted to feeding and aggression was greater.

Thomas et al., (2003) assessed the effects of human activity on the foraging behaviour of

Sanderling, the study sought to determine which types of common beach activities in central

California are most disruptive to shorebird foraging behaviour. The study reports that

urbanisation and coastal development has significantly reduced the suitable beach habitat

available for foraging shorebirds worldwide and tests the general hypothesis that recreational

use of shorebird foraging areas adversely affects the foraging behaviour of Sanderling. The

study was conducted on two long sandy beaches, Monterey Bay California, one site with

high levels of human activity Monterey State Beach and one with relatively low levels of

human activity, Moss Landing State Beach. Foraging observations were made in January -

May and September - December 1999 corresponding to migration patterns. The study

concluded that the number of people, type of activity, free running dogs and proximity to

people significantly reduced the amount of time that the Sanderling spent on consuming

prey. These variables also had a significant effect on the distance at which they moved and

the Sanderling’s response to disturbance. The most significant negative factor was the

presence of free running dogs on the beach. The results from a minimal approach distance

experiment used to test the hypothesis that Sanderling show a higher tolerance to certain

activities, showed that the number of people effected the time spent foraging but activity did

not statistically significantly affect foraging time. The authors suggest the policy

recommendations that people maintain a minimum distance of 30m from areas where

shorebirds concentrate and also strict enforcement of leash laws for dogs.

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Figure: Field observations show 100% of Sanderling responding to humans reacted when

people were 30m or closer. Sanderling tested in the minimal approach distance experiment

reacted to approaching humans at a distance of 26m or less (Thomas et al., 2003)

In a study by Burger (1994) the effect of human disturbance on the foraging behaviour and

habitat use in the Piping Plover (Charadrius melodus) was considered, a bird in which the

reproductive success has been markedly depressed in areas with high human disturbance.

The paper examines the differences in foraging behaviour of Piping Plovers in different

habitats. It was initially predicted that the Piping Plovers would accommodate to the

presence of people by using all available habitats to forage. Observations were made over a

two year period from April 15th

to August 15th

in 1988 and 1989 respectively at Holgate,

Brigantine and Corson’s inlet, New Jersey. The data was gathered between 0700 hrs and

1800 hrs, 5-6 days a week. The study sites were on barrier beach islands with exposed surf,

dunes and backbay habitat. Observers remained at a distance suitable as not to disturb the

birds. Habitat data was obtained using transects and foraging behaviour was obtained using

focal animals, (observed for 2 minutes).

Table: Comparison of foraging piping plovers on the three study sites (1988 and 1989)

The study concluded that the Piping Plovers within each habitat select sites that have fewer

people than the habitat as a whole. The time that the birds devoted to vigilance, (not

foraging for food), is directly related to the number of people near to them, and to the overall

use of the habitat by humans.

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Figure: Mean seconds devoted to foraging by Piping Plover as a function of the number of

people in particular habitats (dunes, ocean, and bay) at three sites in New Jersey (Thomas et

al., 2003)

Thus, in habitats with fewer people the Piping Plover can spend 90% of their foraging time

actively searching for prey and feeding, whereas on beaches with many people they may

spend less than 50% of their time in direct feeding behaviours. The study finishes by saying

that a diversity of habitats allows the birds to move between habitats to minimise interactions

with people and maximise the time devoted to foraging. The results indicate that it is critical

to maintain high habitat diversity in coastal environments to help mitigate competition with

people.

Beale & Monaghan (2004) tested the link between individual state and responsiveness by

manipulating condition via the provision of supplementary food for Turnstone (Arenaria

interpres) on rocky shores in East Lothian, Scotland. Birds whose condition had been

enhanced showed greater responsiveness to standardized human disturbance, flying away

at greater distances from the observer, scanning more frequently for predators and flying

further when flushed. These findings suggest that current management of the impact of

human disturbance may be based on inaccurate assessments of vulnerability.

Baudains and Lloyd (2007) assessed and compared the behavioural responses, egg

temperatures and reproductive success, of shore nesting White-fronted Plovers (Charadrius

marginatus) to disturbance. The case study was conducted along the coastline of the Cape

peninsula, South Africa where the birds nest in exposed sand among dry kelp. Two breeding

sites which experienced both low and high recreational human activity respectively were

looked at. At both localities, daytime nest attentiveness decreased as the number of people

and dogs approaching increased, but sites differed as per figure.

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Figure: Nest attentiveness and disturbance relationship (Baudains and Lloyd 2007)

For any given level of disturbance, incubating birds at the more disturbed site had greater

nest attentiveness. This was reported by Baudains and Lloyd to be achieved by habituation;

the plovers allowed a closer human approach before leaving the nest and returned to the

nest faster after a disturbance effect. Despite this, incubation temperatures were not found

to differ between sites. Nest mortality by natural predation was found to be lower at the high

disturbance site however chick mortality was higher at this site thought to be as a

consequence of predation by domestic dogs and a reduced escape response due to

habituation at the disturbed site. The overall fecundity was found to be substantially higher

at the more disturbed site and Baudains and Lloyd conclude that this demonstrates that

human disturbance and urbanisation does not always compromise the overall reproductive

fitness of wild birds.

The northern New Zealand Dotterel (Charadrius obscurus aquilonius) and the effects of

human approaches to nests are assessed by Lord et al., (2001). Three main approaches

were experimented, walking, running and leading a dog, of which the latter caused the

greatest disruption to incubation. Evidence of habituation to humans was observed on busy

beaches and dogs posed more of a potential threat than humans. Lord et al., (1996)

examine, in this earlier study, the effects of human activity on Dotterel chicks. When people

were present, chicks spent less time feeding in the littoral zone and moved to the sub littoral

and spent less time feeding in general when people were present. It is suggested that high

levels of human disturbance may infer energetic costs to the chicks and fledgling success

may be increased by limiting human access to areas adjacent to breeding sites.

Pfister et al., (1992) investigated human disturbance as a factor that might limit the capacity

of a staging area to support migrating shorebirds. The study uses long term census data to

test the hypothesis that human disturbance at an important coastal migration staging area

has a detrimental effect on patterns of movement in shorebirds because of two factors, 1)

Displacement of shorebirds from preferred resting areas within the study area; and 2)

Abandonment of the study area. The results of the study revealed that four out of seven

species showed one or more types of movement in response to disturbance. The impact of

disturbance was greater on species using the front side of the beach that was heavily

distributed. The abundance of an impacted species was said to be reduced by up to 50% at

high disturbance levels. The Abundance of front beach species, Knot and Short-billed

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Dowitcher (Limnodromus griseus) declined between 1972 and 1989 more than the back

beach species, Grey Plover and Semi-palmated Plover. The Knot and Short-billed

Dowitcher declined more at Plymouth Beach than at two comparable, but less disturbed,

coastal staging areas and more than overall eastern North American population. The study

implicates disturbance as a potential factor in long term declines in shorebird abundance at

Plymouth Beach. The study suggests that the impacts of disturbance could be reduced or

even eliminated by closing one or more small portions of the front beach as refuge resting

areas during migration months.

In a study undertaken by Rogers and Smith (1997) sixteen species of waterbirds,

(Pelecaniformes, Ciconiformes and Charadriformes), in north and central Florida, were

exposed to 4 types of human disturbances, walking, all-terrain vehicle ATV, automobile and

boat. The study aims to determine buffer zones that minimise flushing of foraging or loafing

birds. When approached by walking method the Ring-billed Gull (Larus delawarensis) had

the largest mean flushing distance whilst the shorebirds flushed at shorter distances. Again

gulls flushing distance was greatest when approached by the ATV and Turnstone

demonstrated the shortest flight initiation distance. The study demonstrated that species

varied in their response to the same disturbance in particular with walking and vehicle

approaches. Overall the shorebirds had the shortest flushing distances; gulls were

particularly sensitive to disturbance. The study highlights differences found between this

study and studies by Burger (1981) where gulls were found to flush less frequently relatively

due to habituation. This study estimates flushing distances using a formula based on the

mean plus 1.6495 standard deviations of the observed flushing distance plus 40m:

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Figure: Normalised abundance plotted against vehicle counts a) normal scale, b) log10 scale

with cleavelend smoothing plot/ k = 0.5.

It was concluded that a buffer zone of about 100m would minimise the disturbance caused to

most species of waterbird studied in Florida, follow up studies were recommended.

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A1.2.2 ROOSTING

Many species use the coastline as high tide roosting sites, where large numbers of birds

congregate to roost, disturbance is of particular concern. Peters and Otis (2007) studied into

the effect of human disturbance on shorebirds roost site selection at two temporal scales.

High tide roost selection by eight species of non-breeding shorebird on a critically important

stopover and wintering refuge was studied. The study found the most roosts were used less

than 50% of the time, larger roosts more consistently. At an annual scale, roost length, local

region, substrate and aspect were the principle factors affecting shorebird presence at the

roosts. Among years, Knot avoided roosts that had high average boat activity within 100m,

but disturbance did not appear to be a factor for the other species. Daily roosting behaviour

was found to be primarily influenced by wind speed and the ability of roosts to provide

protection against the wind. Only the Dowitcher appeared to track daily disturbance

appearing to avoid prospective roosts when boat activity within 100m was high. The study

concludes by stating that roost use is highly variable and suggests that conservation

management should aim to provide a wide range of potential roosts that could be used

under different conditions within reasonable distance of feeding areas.

A1.2.3 AIRCRAFT ACTIVITY

Of particular interest to the current study noise levels are assessed by Brown (1990)

measuring the effect of aircraft noise on un-habituated sea birds. The paper reports on a

procedure which exposes sea birds to acoustic stimuli simulating aircraft over-flights, and is

one of the first experiments to attempt to quantify the responses of birds in the wild to noise.

The experiment was conducted on the Great Barrier Reef in Australia and involved exposing

nesting sea bird colonies to pre-recorded aircraft noise, with peak over-flight levels of 65 dB

(A) to 95 dB (A). The sea bird responses were videotaped and the behavioural response of

the birds was analysed. The species that was investigated for this initial study was the

Crested Tern. The results indicated that for the Crested Tern, the maximum responses

observed, preparing to fly or flying away, were restricted to exposures greater than 85 dB

(A). Head turning scanning behaviour was the minimum response and this or a more

intense response was in nearly all birds at all levels of exposure. However and intermediate

response or alert behaviour, was found to demonstrate a strong positive relationship with

increasing exposure. The study also goes on to state that visual stimulus is likely to be an

important component to aircraft disturbance.

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Figure: Mean proportions of the Crested Tern colonies exhibiting different behavioural

responses to the aircraft noise stimuli (Brown 1990)

Another study of particular relevance examining noise levels is presented by Burger (1981)

investigating the behavioural responses of Herring Gull to aircraft noise. The behaviour of

nesting and loafing Herring Gulls was compared when the birds were exposed to supersonic

transport, subsonic aircraft and normal colony noises, 77dB (A) at Jamaica Bay National

Recreational Area. No effects of subsonic aircraft on nesting gulls were noted. However,

when supersonic aircraft flew over significantly more nesting gulls flew from their nests, and

they engaged in more fights when they landed compared with the other conditions. Many

eggs were broken during these fights, and subsequently eggs were eaten by intruders. At

the end of the incubation period there were lower mean clutch sizes in dense sections, (more

potential for fights), of the colony compared with solitary nesting pairs of gulls. For loafing

gulls, significantly more birds flushed when planes flew over compared with immediately

before and after such plane noises.

Table: Behaviour of nesting Herring Gull when exposed to subsonic airplanes, supersonic

transports and normal colony noises, noise levels are in decibels on the A scale (Burger 1981)

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A1.2.4 BOATING ACTIVITY

In a later study by Burger (1998), the effects of motorboats and personal watercraft on flight

behaviour with respect to a colony of Common Tern (Sterna hirundo) in Barnegat Bay New

Jersey was studied. The number of birds flying over the colony was used to test the

hypothesis that there were no differences in flight behaviour as a function of the presence

and type of craft. Observations were made from mid June until August 1997 on a small low

saltmarsh island. A designated boat channel between the island and the adjacent barrier

island is frequently used by motor boats. Access is however restricted, motor boats and

larger craft can move through the channel, personal water crafts, (PWCs), can go entirely

around the nesting island and close inshore. Overall 66% of the variation in the number of

terns flying over the colony was explained by breeding period, type of craft, speed, route

(established channel or elsewhere), the interaction of route and speed and time of day.

However, for the early stage of the reproductive cycle, type of craft, speed and route

explained 95% of the variation. It was found that boats that race elicited the strongest

response as did boats that were outside of the established channel. Boats that travelled

closer to the nesting colonies elicited stronger responses than those that remained in the

channel. Personal water crafts elicited stronger responses than motorboats. The study

concludes to say that personal watercraft should be managed to reduce the disturbance to

colonial-nesting species, by eliminating them within 100m of nesting colonies and restricting

speed near such colonies.

A1.2.5 WILDFOWLING

To test whether hunting disturbance displaced birds from sites, Madsen (1998) established

experimental refuges in two Danish coastal wetlands with hunting-free areas manipulated

annually during a four-year period, followed by permanent refuge establishments, monitored

for a further four years. In both areas species richness increased from before to after the

experiments - this was most pronounced in one of the areas where the refuge included

shallow-watered areas in association with salt marshes. Madsen concluded that prior to

experiments, waterfowl hunting caused displacement of quarry species, resulting in a

species-poor waterfowl community. Refuge creation is thus an efficient management tool to

improve the conservation value and biodiversity of wetlands of importance to waterfowl.

Percival et al., (1998) apply a spatial depletion model to investigate the relationship between

habitat loss and wildfowl numbers at Lindisfarne National Nature Reserve, Northumberland.

The findings of this study have important implications for the management of the site. It is

recognised that factors such as wildfowling, that may be restricting current numbers below

those that could be supported by the food supply, require urgent investigation.

A1.2.6 CONSTRUCTION DISTURBANCE

Burton et al., (1995) examine the effect of disturbance on shorebird numbers in response to

the loss of a roost site and its replacement by an artificial island in Hartlepool, Cleveland.

The area contains nationally important high-water roosts for wintering shorebirds, Purple

Sandpiper (Calidris maritime), Turnstone and Knot. The original stone pier used as a roost

was redeveloped and replaced with a new pier and island built specially for the birds. In the

two years since the development maximum numbers of Turnstone, Oystercatcher and Knot

using the harbour have decreased to a level not in line with national trends. The study

suggests that increased access and the creation of a marina have increased disturbance

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from people and boats. Despite the declines the island has been utilised as the new main

roost site for all species.

Burton et al., (2006) investigated impacts of sudden winter habitat loss on the body condition

and survival of Redshank in Cardiff Bay, UK. The intertidal mudflats of Cardiff Bay were

inundated with freshwater in November 1999 following impoundment by a barrage, resulting

in the displacement of c. 300 Redshank to adjacent habitat on the Severn Estuary.

Movements and the survival of these birds were monitored through observations of colour-

marked individuals. Burton et al., (2006) concluded that their study provides the first

conclusive empirical evidence that habitat loss can impact individual fitness in a bird

population. Adult Redshank displaced from Cardiff Bay experienced poor body condition

and a 44% increase in mortality rate. Without an increase in the recruitment of first-winter

birds, such a change is likely to reduce substantially local population size. Such results

should help to inform governments, planners and non-governmental organizations (NGOs)

seeking to understand how developments might impact on animal populations

A1.2.7 MODELS

In a study by Beale and Monaghan (2004), a behavioural model of perceived predation risk

was used as a framework for understanding the effects of disturbance on cliff nesting birds

encompassing the concept that disturbance increases with increasing numbers of visitors

and decreases with distance from the nest. The model was tested using field data on

nesting success of two species of bird, the Black-legged Kittiwake (Risa tridactyla) and the

Guillemot (Uria aalge). In both cases predation risk was deemed as a good indicator of the

effects of disturbance. The model uses two parameters, D distance and N, number of

predators (humans). The chance of survival P(s) increases the further away the predator is.

This shows that of the number of predators and the distance increase in direct proportion

then the risk to the bird remains constant. The data were collected from a seabird colony at

St Abbs Head in south east Scotland. Target nests were selected and 106 Black-legged

Kittiwake nests and 241 Common Guillemot nests were used. Each nest was observed daily

and nest contents recorded where possible. People at the site were counted electronically

as they entered the reserve and 19 visitor viewpoints were identified with people being

counted at these viewpoints. The average people minutes per hour were calculated for each

view point and this was used as an indicator of human disturbance. The overall relationship

between the nesting success in the two species and the change in visitor numbers was

plotted, demonstrated in figure below.

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Figure: Expected nesting success as a function of change in visitor numbers (Beale and

Monaghan 2004),

The findings of the study suggest that fixed set back distances and buffer zones are likely to

be inappropriate conservation measures in situations where numbers of visitors vary spatially

and temporally. It is suggested in the study that when managing access to wildlife areas,

there is a need to ensure that larger parties of visitors are kept further back from the nesting

areas of vulnerable species or that set back distances are set for the largest parties

expected to visit the site.

Beale (2007) investigated the management of visitor access to seabird colonies. Beale

suggests that managers lack guidelines as to whether conservation interests are best met by

spreading visitors thinly throughout a reserve or by aggregating them in a small area. He

describes how relationships between disturbance impact and disturbance pressure (the

dose–response curve) can be used to address this issue. Spatial simulations of two different

models of visitor distribution (one more aggregated than the other) were generated. It is

shown that the optimal visitor distribution is likely to depend on the sensitivity of the species

and the overall visitor pressure. Importantly, it was found that in certain circumstances

optimal management can shift from one management option to the other if visitor numbers

cross a certain threshold. Published relationships predicting nesting success of Common

Guillemot and Black-legged Kittiwake to assess optimal management at three nature

reserves in Scotland were used as empirical evidence. Two of these nature reserves were

on Orkney, with the third being at St Abbs Head. It was shown that optimal management for

Guillemot depends on the number of people and the distance between the people and the

birds. At sites with high disturbance pressures, Beale suggests that management should

aim to aggregate visitors in as small an area as possible, whereas at sites with lower

disturbance pressure, an even distribution of visitors is favoured. Black-legged Kittiwake

models were not generally accurate, and consequently only site-specific guidelines could be

generated, where an even distribution was favoured.

Liley et al., (2007) assess the population consequences of human disturbance on the Ringed

Plover using a game theory approach. The paper identifies that whilst many studies reveal

behavioural impacts or direct effects of disturbance on breeding success or survival, these

studies cannot be extended to predict the impact on population size. Liley et al., (2007)

present a population model that enables the prediction of the effect that changes in human

numbers visiting a stretch of coastline has on the size of a Ringed Plover population. The

study was undertaken at Snettisham, Norfolk. Human disturbance in this study area was

found to affect Ringed Plover via the birds avoiding areas of high disturbance and, through

the accidental trampling of small numbers of nests by walkers. Using habitat variables and

the level of human disturbance the model can predict sites available to the population.

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Breeding success is predicted and by the addition of known density dependant adult

mortality the equilibrium population size is predicted. The model is then used to predict the

population at given levels of disturbance. The model predicted that if nest loss from human

activity was prevented via the addition of fencing then the Ringed Plover population size

would increase by 8%. A complete absence of human presence according to the model

would lead to a population increase of 85%. If numbers of people were to double then the

model predicts a 23% decrease in the population.

A1.3 Offshore: UK and Worldwide

Desholm et al., (2006) reviewed remote techniques for counting and estimating the number

of bird-wind turbine collisions at sea. Another study by Drewitt and Langston (2006) reviewed

existing data available on the impact of wind farms on birds. Evidence of the four main

effects: collision; displacement due to disturbance; barrier effects; and habitat loss, is

presented and discussed. Langston and Pullan (2002) undertook an analysis of the effects

of wind farms on birds, and guidance on environmental assessment criteria and site

selection issues. A review of the literature identified the main potential hazards to birds from

wind farms to be: (1) disturbance leading to displacement, including barriers to movement;

(2) collision mortality; and (3) direct loss of habitat to wind turbines and associated

infrastructure. Again with reference to windfarms Fox et al., (2006) investigated the

information needs to support EIAs of the effects of European offshore wind farms on birds.

Garthe and Hüppop (2004) investigated scaling possible adverse effects of marine wind

farms on seabirds and thus discussed developing and applying a vulnerability index. Their

work concentrated on the German part of the North Sea and the Baltic Sea.

Harris (2005) reports on the development of practical guidelines for aircraft operations near

concentrations of birds in Antarctica. Aircraft operations have the potential to disturb and to

impact negatively on bird life. A gradient of increasing behavioural response is evident in

birds when exposed to increasing aircraft stimulus. The most major disturbance is likely to

lead to impacts on the health, breeding performance and survival of individual birds, and

perhaps bird colonies. The principal recommendations of the guidelines are that bird

colonies should not be overflown below 2000 ft (~610 m) above ground level and landings

within 1/2 nautical mile (~930 m) of bird colonies should be avoided wherever possible.

These guidelines are less stringent and less specific than those that were recommended by

the SCAR specialist group on birds, and represent a compromise to accommodate

operational needs. While the adoption of clear and consistent guidelines for the operation of

aircraft in Antarctica is welcome in that this provides practical advice that is likely to reduce

incidences of close aircraft/bird encounters, there remains insufficient knowledge of the

interactions between aircraft and birds in Antarctica, and the consequent impacts on

individual birds and on bird populations. It is important, therefore, that the guidelines

adopted are considered interim, and should be kept under scrutiny with revisions made as

new and improved research results appear.

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Table: Factors influencing the interaction of aircraft and birds and the potential magnitude of

impact. (Harris 2005)

Table: Examples of guidelines adopted for aircraft operations in Antarctic/sub-Antarctic (Harris

2005)

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Table: Distance which disturbance was apparent in Antarctic birds in experimental flight

observations (Harris 2005)

Table: Minimum horizontal and vertical separation distances for aircraft operations close to

concentrations of birds in Antarctica as recommended by the SCAR Bird Biology Subgroup

(from SCAR 2000) (Harris 2005)

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Table: Suggested guidelines for pilots operating over bird colonies in Antarctica (Harris 2005)

Ronconi and Cassady-St. Clair (2002) in a study into boat disturbance on the Black

Guillemot (Cepphus grille) in the Bay of Fundy put forward management options to reduce

effects of this type of disturbance on foraging Black Guillemot. It was concluded that at the

site studied, a set back distance of 600m from the shore with a speed limit of 25 km/h would

reduce Guillemot flushing probability to 10% most of the time. It is suggested that these

thresholds are and can be relevant to other locations and colonial waterbird species.

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Table: Results of a logistic regression analysis of all variables predicted to flushing probability

of Black Guillemot (Ronconii and Cassady-St. Clair 2002)

Table: Management options for speed limits and set back distances to reduce flushing

probability to approximately 0.1 (10%) (Ronconii and Cassady-St. Clair 2002)

A1.4 Terrestrial UK and Worldwide

Atkinson et al., (2002) assess the potential impact of changes in farmland type on lowland

farmland birds by examining the extent to which distributions (as shown by national atlases

of summer and winter birds) of different species are associated with arable, pastoral or

mixed-farming landscape types. This study concentrated on lowland farmland in England

and Wales only. Batten (1977) investigated sailing on reservoirs and its impact on birds. In

particular the Brent Reservoir, North West London, was used as a case study. The study

showed that a few species of wildfowl, e.g. Mallard (Anas platyrhynchos), Tufted Duck

(Aythya fuligula), Pochard (Aythya farina), still use the reservoir in autumn and winter despite

an intensification of sailing activities. This use and the successful breeding of Great Crested

Grebe (Podiceps cristatus) and other species of water birds depends on the existence of a

large enough part of the reservoir which is shallow and marshy and not accessible to boats.

As there is some suggestion that larger flocks are more sensitive to disturbance than smaller

ones, refuges may be made more effective by proper screening.

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Table: Number of ducks present at weekends in the years before and after increased sailing

activities (October - March) (Atkinson et al., 2002)

Distances at which flocks of ducks would move from an oncoming sailing dinghy were

estimated visually using physical features of the surroundings and checked by reference to a

large-scale Ordnance Survey map. The distances were measured to the birds which flew

first in the flock.

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Table: Distances from sailing craft at which point the Tufted Duck and Potchard took to the

wing (Atkinson et al., 2002)

Evans and Day (2001) present a case study of Loch Neagh, Northern Ireland and ask the

question does shooting disturbance affect diving ducks wintering on large shallow lakes.

They report that wildfowl shooting affects wildfowl populations directly by the kill but also

indirectly by disturbance. The seasonal effects of shooting disturbance on the daytime

distributions and behaviours of wintering Pochard, Tufted Duck, Scaup (Aythya marila) and

Goldeneye (Bucephala clangula) was studied on Lough Neagh during the winter of

1998/1999. The distribution of wintering Pochard, Tufted Duck and Scaup were all shown to

be affected by shooting disturbance. The most important factors to consider when applying

conservation measures to diving duck populations wintering on lakes with similar attributes

are discussed.

Evans and Day (2002) discuss hunting disturbance on Lough Neagh and the effectiveness

of waterfowl refuges. A small number of refugia have been provided to limit the effects of

shooting disturbance on the wintering populations. The use of one of these refuges (Doss

Bay) was studied during the winter of 1997/8 and compared with a non-refuge site (Brockish

Bay) during the winter of 1998/9. Shooting intensity was greater at weekends than midweek,

and significantly more birds used the refuge at weekends than midweek during the shooting

season. In contrast, significantly fewer birds were observed in Brockish Bay at weekends.

This trend ceased when the shooting season closed, suggesting that the effect was due to

shooting disturbance. Furthermore, significantly fewer birds used Doss Bay after the

shooting season had closed, whereas significantly more birds were observed at Brockish

Bay. Shooting disturbance had the greatest impact on dabbling duck species and rails at

both sites. Diving ducks moved away from shoreline disturbance to shallow areas where

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they could still feed. The value of shoreline refuges for waterfowl populations on lakes is

also discussed.

A study into the habitat choice of Pink-footed Geese (Anser brachyrhynchus) was

undertaken by Gill (1996) which then quantifies the constraints which determine the winter

site usage. The study states that the number of geese a wintering area can support

depends on the amount of food in that area and the restrictions that limit the bird’s usage of

this food source. Limiting factors are said to include travel distance from roost site, selection

of sites within the feeding range and the extent to which these sites are exploited by

humans. The study was conducted from1990 to 1993 in North Norfolk on Scott Head Island;

the study fields contained three main crop types.

a) b)

Figure: a) The relationship between distance of sugar beet fields with the field usage by the

geese. b) The effect of potential disturbance measured by the distance from the flock to the

road on the proportion of the initial crop that was depleted by the geese (Gill 1996).

For most of the winter the birds fed on the sugar beet crop which was noted only to account

for 8 and 13% of fields. The geese were seen to use the fields that were closest to the roost

site first and then gradually, as the beet was depleted the geese moved onto the fields

further away. Importantly in terms of human disturbance, fields closer to the roads were

used significantly less. The study concludes by suggesting management measures; by

minimising the disturbance of the geese on the sugar beet, (which commercially has no

value), it may effectively increase the time that the geese spent on the beet by 80%.

Madders and Whitfield (2006) assess the potential impacts to raptors from upland wind farm

turbines.

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Table: Summary of the results of several studies which have investigated potential

displacement effects on raptors at wind farms (Whitfield 2006)

One of the UK’s largest flocks of Pochard and Tufted Duck winters in Manchester’s busy

dockland redevelopment area. Marsden (2000) examined the effects of human disturbance

on the population, and used this information to recommend minimal land-use restrictions that

will help ensure the population’s continued use of the site. Birds fed at the docks every

night, but on 75% of days, the flock flew to suburban or rural refuges in response to

disturbance. The common causes of disturbance, particularly pedestrians, did not affect the

duck greatly, but disturbances associated with building and redevelopment of the site (e.g.,

machinery) often made duck evacuate the dock. While birds were no less likely to evacuate

the docks as the winter progressed, they did show some short-term flexibility in their

responses to disturbance. For example, birds appeared able to sit out disturbances

throughout the afternoon if they had avoided evacuation of the docks during the morning.

Birds spent only a small proportion of time feeding, and feeding activity was not heightened

following periods of exclusion from the docks due to disturbance. Daytime feeding activity

was elevated during periods of lowering temperatures, and despite heavy disturbance at the

site, the impact of disturbance may only be significant during the coldest period of the winter.

During very cold spells, it is important to limit the incidence of unusual disturbances, such as

evening concerts and waterborne activities which tend to make duck evacuate the site.

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Table: Responses of diving duck to disturbances at Salford Docks (1996-1997) (Marsden, 2000)

Understanding and predicting the likely consequences of anthropogenic disturbance on

species and ecosystems is a major prerequisite of achieving the sustainable use of natural

resources. It is also a key element in the management of sites with statutory designation.

O’Connell et al., (2007) provide (1) an overview of the field and analytical methodologies

contributing to the development of an integrated method for collecting multi-scale bird,

resource and disturbance data in freshwater systems, and (2) an overview of the drivers and

need for such data in sustainable resource management. Bird and ‘disturbance event’

observations were carried out for each of eight study lakes in the Cotswold Water Park

between November and March in the winters of 2004/05 and 2005/06. For the purpose of

this study, all human activities (‘events’) were recorded in order to remove subjective views

of what constitutes a disturbance to waterbirds.

Rees et al. (2005) present a study into the behavioural responses of Whooper Swan

(Cygnus c. cygnus) to various human activities. The variation in behaviour to disturbance is

analysed at Black Cart Floodplain, Glasgow, to determine whether their susceptibility to

human activity varies with, time, location and the type of disturbance. Whooper Swan

behaviour was monitored from a hidden vehicle as not to disturb the flock, activities were

recorded by making flock scans at 10-15 min intervals. Human activities and its affect on

the swans was also monitored, both potential, (human present), and actual, (human causing

>5% swans alerted). The results of the study found that feeding activity varied within and

between years and in relation to feeding site but less variation was found in time spent alert.

The disturbance frequency resulting from human activity was found to be lower with

increasing flock size and with increased distance to the nearest road or track. The distances

that the humans could approach before alerting the birds also varied with field characteristics

and with the type of disturbance involved. Importantly, the study found that the distance at

which 5% of the flock became alert, as a result of human activity, decreased with the number

of previous disturbance incidents in the day. This indicates that the swans become less

sensitive to disturbance if the frequency of daily disturbance is high, however it was not

proven that this habituation persists over long periods. The results also found that the time

taken for the birds to resume normal behaviour after a disturbance event varied with the type

and duration of disturbance. Pedestrians altered the bird’s behaviour for longer periods than

vehicles and aircraft. Recovery rates were also associated with field size, flock size and the

proportion of the flock alerted. Feeding activity was influenced by disturbance explaining

4.9% of the variance in the proportion feeding per hour. Alert activity was found to be

predominantly influenced by disturbance events.

Stone Curlew (Burhinus oedicnemus) have a vulnerable population status in the UK after a

large population decline and range contraction since the 1930s (Taylor et al., 2007). Much

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Stone Curlew breeding habitat is open-access land designated under the Countryside and

Rights of Way Act 2000. In order to guide the conservation and habitat management for this

species whilst allowing recreational access, a tool known as the Stone Curlew Access

Response Evaluator (SCARE) has been developed. SCARE offers a method to assess the

effects of scenarios for future changes in disturbance type, routes and frequency and will be

valuable in making informed decisions about the management of public access to Stone

Curlew breeding sites and the deployment of habitat creation measures.

Quan et al., (2002) undertook surveys on migratory waterbirds and their habitats at Lashihai

Lake, China, between October 1999 and April 2000. Five fixed points, representing different

degrees of habitat disturbance and quality, were selected around the lake. Counts were

used (n=30) to compare diversity and abundance of waterbirds at each point and evaluate

the effects of habitat disturbance. The distribution of waterbirds was affected by

disturbance, with more than one-third of the total species and nearly half of the total

individuals occurring at the least disturbed point. Species richness was weakly and

abundance was strongly correlated to habitat disturbance, but not to habitat quality. Habitat

destruction and use of canoes were prominent at the lake. Naxi ethnic fishermen (n=37)

were interviewed. They caught 570 waterbirds between October 1999 and March 2000 in

fishing nets. An estimation of the total number of waterbirds been trapped on the lake is

6,164. Diving species were most susceptible. Conservation measures that should

implement immediately include the cessation of habitat destruction, better plan for the

development of tourism, a reduction in the number of canoes and zoning of the non-fishing

area.

In a study by Pease et al., (2005) the effects of human disturbance on the behaviour of

wintering ducks was examined. The responses of 7 species of dabbling ducks to 5 different

experimental human activities were looked at. These activities were, a pedestrian, a

bicyclist, a truck travelling at 2 different speeds and an electric passenger tram. The study

was conducted from 8 November until 20 February 1998-1999 and 1 November- 15 February

1999-2000. The species looked at were the American Black Duck (Anus rubripes), Gadwall

(A. strepera), Mallard, Northern Pintail, (A. acuta), American Widgeon (A. Americana),

Northern Shoveler (A. clypeata) and the Green Winged Teal. It was found that the

responses of the ducks were dependant on the type of disturbance, species and distance

from disturbances. People walking and biking caused the greatest disturbance, more so

than vehicles. The Northern Pintail was the least sensitive whereas the American Widgeon,

Green Winged Teal and Gadwall were most sensitive. Importantly, the ducks were more

likely to fly when closer to the sources of disturbance. The study suggests that managers

may find the information useful when making decisions about public visitation and

disturbance of dabbling ducks.

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Figure: Threshold model for the relative breeding density of birds plotted against traffic noise,

where T is the threshold value and R the value at the roadside. The decrease factor of the

density = area A/(area of A + B) (Pease et al., 2005)

In a study by Reijnen et al., (1997) into the disturbance by traffic of breeding birds, effects

are evaluated and considerations are put forward for managing road corridors. The study

states that densities of bird species in woodland and open habitat in broad zones are

strongly reduced in such areas adjacent to busy roads. This density reduction is related to a

reduction in habitat quality and this can be attributed to traffic noise in the main. Density

underestimates habitat quality and thus the effects due to traffic noise are also probably

larger than have been established and thus species that do not show a density effect may

still be adversely affected by traffic noise. Charadriidae, (Waders), are only investigated in

agricultural grassland but were affected by traffic.

Table: Maximum size of the disturbed zone adjacent to main roads (m) that has reduced

density of breeding birds when probable unrealistic values are not considered (Reijnen et al.,

1997)

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Table: Range of threshold values for traffic noise (dB(A)) of breeding birds (probable

unrealistic values are shown parentheses; below the threshold the density is not affected

(Reijnen et al., 1997)

The Neusiedler See–Seewinkel National Park, Austria is confronted with a remarkable

increase in tourism and recreational activities during the last years. The “Koppel” area,

situated on the eastern shore of the lake, is one of the most important breeding sites for

Greylag Geese. Behaviour and distribution of the geese on the breeding site as well as

touristic activities on the adjacent road leading along the Koppel were examined by Steiner

and Parz-Gollner (2003) to investigate relations and interactions between the Greylag Goose

population and tourism. Taking into account the excellent weather and breeding conditions

in the year 2000 the results of the survey indicate a stable or even rising Greylag population,

increasing numbers of visitors and high disturbance frequencies in the vicinity of the study

area. The number of disturbances on the adjacent road seems to affect the suitability of the

site in general, leading to a specific temporal and spatial distribution of the birds, whereas

different disturbance qualities result in changes of the bird’s behaviour. 83% of potential

disturbances observed on the Koppel road were represented by cyclists, the share of cars is

8%, and the share of pedestrians is 6%, tractors, motorcycles and other disturbance factors

amount to 1% each. The goose population on the Koppel road is almost permanently

confronted with high human induced activities during daytime. In the morning hours and

about noon peak numbers of more than 3 disturbances per minute were recorded. In the

afternoon approximately 2.5 disturbances per minute have been recorded. The maximum

value was registered on 10.06.2000 around 10 am, when more than 10 people per minute

were driving or walking along the road.

A1.5 General Papers

Gill (2007) summarised the various approaches to measuring the effects of human

disturbance on birds.

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Table: Examples of typical measures of four different types of effects of human disturbance on

animal populations, and the information that each measure provides (Gill 2007)

Hill et al., (1997) report that the levels of disturbance experienced by birds in the UK are

difficult to estimate but the available evidence suggests that they could be considerable with

significant implications for bird conservation. This paper addresses three sources of

disturbance to birds in the UK: from recreational pursuits; developments (construction and

operation); and hunting. Legislative requirements to take account of disturbance impacts

are increasing but there has been little research to provide a sound scientific basis for impact

assessment. The first by Underhill et al., (1993) adopts a multivariate approach and found

that although the larger sites suffered more disturbances they were still able to support both

recreation and water birds concurrently. The second is Marsden (1995), The study showed

that the numbers of quarry species using the area over which hunting was prevented

increased between 4 and 20 fold, the abundance of protected species also increased there

was however a time lag in response. The third example is the work of Goss-Custard 1993 &

1995 and Goss-Custard et al., (1995)

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Figure: Types of disturbance of wildfowl and waders with likely responses across a gradient of

increasing sensitivity (Goss-Custard et al., 1995)

A review of studies of the effects of disturbance on birds between 1970 and the present

reveals considerable scope for improvement in the way in which results of research are

applied. Disturbance effects (e.g. local site movements) and disturbance impacts (where a

population is affected) are often confused. Three example studies are reviewed which may

point the way forward. The first takes a multivariate approach to assess the influence of

disturbance on the use of sites by birds; the second takes an experimental approach by

manipulating the source of disturbance; the third takes a modelling approach to establish

metapopulation impacts of disturbance. From this analysis, an outline of research priorities

at local, regional and flyway scales is proposed.

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Table: Number of studies addressing different types of disturbance affecting birds, papers

published pre 1970 to 1995

Table: Number of published studies of disturbance impact in relation to ornithological

objective up to 1991

Figure: Schematic model of the relationship between disturbance and habitat loss, food

supply, intake rate, carrying capacity and importance to metapopulations

In the study done by Robinson and Pollitt (2002) Wetland Bird Survey Data were reviewed to

investigate the sources and scale of potential disturbance to waterbirds in the UK. Volunteer

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counters recorded human activity and perceived waterbird disturbance. Results found that

the frequency of disturbance peaked during the late summer, 26 % of which was

anthropogenic in cause. Coastal water birds were found to be most likely to be disturbed by

walkers, shooters and large aircraft.

Figure: Numbers of WeBS counts during which various human activities were recorded at

inland and coastal sites (Robinson and Pollitt 2002)

Goss-Custard et al., (2006) looked at critical thresholds of disturbance by people and raptors

in foraging wading birds. Disturbance can cause birds to spend energy flying away

subsequently loosing feeding time. The study aims to show how frequently birds can be

disturbed and put to flight before their fitness is reduced. Individual based behavioural

models are used to establish critical thresholds for the frequency with which wading birds

can be disturbed before they die of starvation. The study used Oystercatcher in the Somme

where disturbance levels are 1.73 times per daylight hour. The modelling showed that birds

can be disturbed up to 1.0 -1.5 times per hour before their fitness is reduced in winters with

good feeding conditions, (abundant Cockles and mild weather), but only up to 0.2 - 0.5 times

per hour when feeding conditions are poor, (scarce Cockles and severe winter weather).

This enables thresholds to be established and set.

In a study by Blumstein (2003) in Australia and Tasmania, flight initiation distance or flushing

distance as an anti predator defence i.e. the distance at which animals move away from

threats is looked at in relation to starting distance. The study is approached from an

economic perspective in terms of costs and benefits of remaining or escaping. Individual

birds were identified and walked towards directly at a steady pace (approx 0.5 m/sec)

maintaining eye contact. The study focussed on birds that were either foraging or engaged

in some form of relaxed behaviour e.g. preening or roosting, this therefore assumes that the

birds were relaxed before the approach. It was noted that most of the birds resumed their

previous activity in a different location within 30 seconds of initially moving. The study was

conducted in a range of habitats using a broad range of starting distances measured in

paces. The study found that in 64 out of 68 species there was a significant relationship

between starting distance and flight initiation distance as shown in the figure below.

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Figure: Modification of Ydenburg and Dill (1986) economic model of flight initiation distance.

The cost of flight increases with distance to an approaching predator and as the distance to an

approaching predator increases the cost of remaining decreases. Optimization occurs at the

intersection D optimal.

The study concludes by stating that as predicted by the economic models, species generally

assess risk dynamically and flush at a greater distance as starting distances increase. Flight

initiation distance does vary between individuals within a species but is influenced by starting

distance and that starting distances also varied widely. The study suggests that starting

distances should be standardised and as a management consideration, the set back

distances should be much larger than the mean flight initiation distance.

Blumstein et al., (2005) looked at inter-specific variation in avian responses to human

disturbance. The study identified the lack of a general framework to study multiple species.

A number of potential predictive variables affecting multiple species responses to human

disturbance were utilised and a simulation model was developed that investigates the inter-

specific variation in different parameters of disturbance with variation in human visitation.

The study found that fitness related responses such as the quantity of food consumed by a

species are sensitive to the distance at which animals detect humans, the frequency of the

disturbance and how these interact but are less sensitive to other characteristics. In the

study, avian alert distance was examined, (the distance at which the animal is first orientated

to the approaching threat, a proxy for detection distance), across 150 species, controlling for

phylogenetic effects. It was found by Blumstein et al., (2005) that larger species had greater

alert distances when compared to smaller species which could increase local spatial and

temporal limitations on suitable habitat with increasing human disturbance, (visitation). The

study concludes by stating that body size could be a potential predictor of responses to

anthropogenic disturbances across species and could be used by conservation managers

making decisions about human visitation to sites. The study goes on to say that indicators of

disturbance with low inter-specific variation should be used and species specific responses

should be identified as well as life history and natural history of species, this would achieve a

more generalised model.

Gill et al., (2001) present a study into why the behavioural responses may not reflect the

population consequences of human disturbance. The study discusses whether changes in

behaviour such as avoidance are likely to be good measures of the relative susceptibility of

species to human disturbance. The point is put forward, that the response of animals to

predation risk is in effect exactly the same as that to disturbance, thus a species with

suitable habitat nearby may avoid disturbance because it has alternative sites to retreat to.

Appendix 1

Page li Institute of Estuarine & Coastal Studies

Animals without this alternative habitat may be forced to remain despite the disturbance

regardless as to whether survival or reproductive success is affected; therefore avoidance

behaviour may vary both spatially and temporally depending on the prevailing local

conditions. It is suggested that protection should be focussed on those species whose

populations are declining as opposed to those who appear to be intolerant of disturbance in

a behavioural context only

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