-For the proposed Scarlet Ibis WEF, Eastern Cape Ibis Wind Energy... · This is the fifth and final...

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Final Progress Report of a 12-month Long-Term Bat Monitoring

Study

-For the proposed Scarlet Ibis WEF, Eastern Cape

Compiled by: Werner Marais

July 2017

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PREPARED FOR:

InnoWind (Pty) Ltd – EDF EN Group 16 Irvine Street, Richmond hill

Port Elizabeth 6001

www.innowind.com

+27 (0)41 487 2418 Fax: +27 (0)41 484 3038

By

2015/364493/07 Somerset West

Cape Town 7130

www.animalia-consult.co.za

Ref: R-1707-26

http://www.innowind.com/

http://www.animalia-consult.co.za/

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Appointment of Specialist

Specialist Company: Animalia Consultants (Pty) Ltd

Fieldwork conducted by: Werner Marais

Report done by: Werner Marais

Appointed by: Innowind (Pty) Ltd

For: 12 Month pre-construction bat sensitivity monitoring

Independence:

Animalia Consultants (Pty) Ltd has no connection with the developer. Animalia Consultants

(Pty) Ltd is not a subsidiary, legally or financially of the developer; remuneration for services

by the developer in relation to this proposal is not linked to approval by decision-making

authorities responsible for permitting this proposal and the consultancy has no interest in

secondary or downstream developments as a result of the authorization of this project.

Applicable Legislation:

Legislation dealing with biodiversity applies to bats and includes the following:

NATIONAL ENVIRONMENTAL MANAGEMENT: BIODIVERSITY ACT, 2004 (ACT 10 OF 2004;

Especially sections 2, 56 & 97)

The act calls for the management and conservation of all biological diversity within South

Africa. Bats constitute an important component of South African biodiversity and therefore

all species receive additional attention to those listed as Threatened or Protected.

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TABLE OF CONTENTS

1 OBJECTIVES AND TERMS OF REFERENCE FOR PRECONSTRUCTION STUDY ................. 10

2 INTRODUCTION ....................................................................................................... 10

2.1 The Bats of South Africa ............................................................................................ 11

2.2 Bats and Wind Turbines ............................................................................................ 12

3 METHODOLOGY ....................................................................................................... 14

3.1 Site Visit Information................................................................................................. 16

3.2 Assumptions and Limitations .................................................................................... 17

4 RESULTS AND DISCUSSION ....................................................................................... 18

4.1 Land Use, Vegetation, Climate and Topography....................................................... 18

4.2 Literature Based Species Probability of Occurrence ................................................. 21

4.3 Ecology of bat species that may be largely impacted by the Scarlet Ibis WEF ......... 24

4.4 Transects ................................................................................................................... 26

4.4.1 Second Site Visit ......................................................................................... 26

4.4.2 Third Site Visit ............................................................................................ 28

4.4.3 Fourth Site Visit ......................................................................................... 31

4.4.4 Fifth Site Visit ............................................................................................. 34

4.5 Sensitivity Map .......................................................................................................... 36

4.6 Passive Data .................................................................................................................. 40

4.6.1 Abundances and Composition of Bat Assemblages .......................................... 40

4.6.2 Temporal Distribution ..................................................................................... 43

4.6.3 Relation between Bat Activity and Weather Conditions ................................... 49

5 IMPACT ASSESSMENT OF THE PROPOSED WEF ON BAT FAUNA ................................ 59

5.1 Construction phase ................................................................................................... 59

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5.1.1 Impact: Loss of foraging habitat ................................................................. 59

5.2 Operational phase ..................................................................................................... 60

5.2.1 Impact: Bat mortalities due to direct blade impact or barotrauma during

foraging activities .................................................................................................... 60

5.2.2 Impact: Increased likelihood of bat mortalities due to artificial lighting ...... 61

5.3 Decommissioning phase............................................................................................ 62

5.3.1 Impact: Temporary loss of foraging habitat ................................................ 62

6 CUMULATIVE IMPACT ASSESSMENT ......................................................................... 64

7 PROPOSED MITIGATION MEASURES AND DETAILS ................................................... 67

8 CONCLUSION ........................................................................................................... 70

9 REFERENCES ............................................................................................................ 72

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Figure 1: Map overview of the proposed Scarlet Ibis WEF turbine layout.

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Figure 2: Map overview of the proposed Scarlet Ibis WEF turbines (South).

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Figure 3: Map overview of the proposed Scarlet Ibis WEF turbines (North).

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Figure 4: Overview of the location of the passive monitoring system (Met Mast) on the Scarlet Ibis WEF.

1 OBJECTIVES AND TERMS OF REFERENCE FOR PRECONSTRUCTION STUDY

Study bat species assemblage and abundance on the site.

Study temporal distribution of bat activity across the night as well as the four seasons

of the year in order to detect peaks and troughs in activity.

Determine whether weather variables (wind, temperature, humidity and barometric

pressure) influence bat activity.

Determine the weather range in which bats are mostly active.

Develop long-term baseline data for use during operational monitoring.

Identify which turbines need to have special attention with regards to bat monitoring

during the operational phase and if and identify if any turbines occur in sensitive areas

and need to be shifted into less sensitive areas or removed from the layout.

Detail the types of mitigation measures that are possible if bat mortality rates are

found to be unacceptable, including the potential times/ circumstances which may

result in high mortality rates.

2 INTRODUCTION

This is the fifth and final progress report for a twelve-month bat monitoring study at the

proposed Scarlet Ibis WEF approximately 4.5 km from Motherwell, Port Elizabeth, in the

Eastern Cape.

The proposed 20MW Scarlet Ibis WEF will consist of the following infrastructural components:

Up to 9 wind turbines with a rotor diameter of up to 90m, a hub height of up to 100m

and blade length of up to 45m (number of turbines may be reduced when using higher

output models, still maintaining a final total output of <20MW for the facility);

Foundations (up to 400m²) for each wind turbines;

3,500m2 for crane hardstand per turbine;

25m2 area for switchgear and/or transformer at each turbine;

Internal access roads of between 8m (during operation) and 14m (during construction,

to be part rehabilitated) wide to each turbine;

Medium voltage cabling between turbines and the switching station, to be laid

underground where technically feasible;

Overhead medium voltage powerlines between turbine rows where necessary;

Connecting at medium voltage (22kV) to the municipal grid option 1: Coega Main

substation and option 2: Motherwell Main substation

An up to 7,500m2 “Switching station and control area” which would comprise of the

electrical switching equipment, battery storage capacity, electrical compensation

equipment, control room, communications, and storage;

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Temporary infrastructure including a site camp and a laydown area of approximately

30m2 per turbine (all to be rehabilitated post construction)

Three factors need to be present for most South African bats to be prevalent in an area:

availability of roosting space, food (insects/arthropods or fruit), and accessible open water

sources. However, the dependence of a bat on each of these factors depends on the species,

its behaviour and ecology. Nevertheless, bat activity, abundance and diversity are likely to be

higher in areas supporting all three above mentioned factors.

The site is evaluated by comparing the amount of surface rock (possible roosting space),

topography (influencing surface rock in most cases), vegetation (possible roosting spaces and

foraging sites), climate (can influence insect numbers and availability of fruit), and presence

of surface water (influences insects and acts as a source of drinking water) to identify bat

species that may be impacted by wind turbines. These comparisons are done chiefly by

studying the geographic literature of each site, available satellite imagery and observations

during site visits. Species probability of occurrence based on the above-mentioned factors are

estimated for the site and the surrounding larger area (see Section 4.2).

General bat diversity, abundance and activity are determined by the use of a bat detector. A

bat detector is a device capable of detecting and recording the ultrasonic echolocation calls

of bats which may then be analysed with the use of computer software. A real-time expansion

type bat detector records bat echolocation in its true ultrasonic state which is then effectively

slowed down 10 times during data analysis. Thus, the bat calls become audible to the human

ear, but still retains all of the harmonics and characteristics of the call from which bat species

with characteristic echolocation calls can be identified. Although this type of bat detection

equipment is advanced technology, it is not necessarily possible to identify all bat species by

just their echolocation calls. Recordings may be affected by the weather conditions (i.e.

humidity) and openness of the terrain (bats may adjust call frequencies). The range of

detecting a bat is also dependent on the volume of the bat call. Nevertheless, it is a very

accurate method of recording bat activity.

2.1 The Bats of South Africa

Bats form part of the Order Chiroptera and are the second largest group of mammals after

rodents. They are the only mammals to have developed true powered flight and have

undergone various skeletal changes to accommodate this. The forelimbs are elongated,

whereas the hind limbs are compact and light, thereby reducing the total body weight. This

unique wing profile allows for the manipulation wing camber and shape, exploiting functions

such as agility and manoeuvrability. This adaption surpasses the static design of the bird wings

in function and enables bats to utilize a wide variety of food sources, including, but not limited

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to, a large diversity of insects (Neuweiler 2000). Species based facial features may differ

considerably as a result of differing life styles, particularly in relation to varying feeding and

echolocation navigation strategies. Most South African bats are insectivorous and are capable

of consuming vast quantities of insects on a nightly basis (Taylor 2000, Tuttle and Hensley

2001) however, they have also been found to feed on amphibians, fruit, nectar and other

invertebrates. As a result, insectivorous bats are the predominant predators of nocturnal

flying insects in South Africa and contribute greatly to the suppression of these numbers.

Their prey also includes agricultural pests such as moths and vectors for diseases such as

mosquitoes (Rautenbach 1982, Taylor 2000).

Urban development and agricultural practices have contributed to the deterioration of bat

populations on a global scale. Public participation and funding of bat conservation are often

hindered by negative public perceptions and unawareness of the ecological importance of

bats. Some species choose to roost in domestic residences, causing disturbance and thereby

decreasing any esteem that bats may have established. Other species may occur in large

communities in buildings, posing as a potential health hazard to residents in addition to their

nuisance value. Unfortunately, the negative association with bats obscures their importance

as an essential component of ecological systems and their value as natural pest control

agents, which actually serves as an advantage to humans.

Many bat species roost in large communities and congregate in small areas. Therefore, any

major disturbances within and around the roosting areas may adversely impact individuals of

different communities, within the same population, concurrently (Hester and Grenier 2005).

Secondly, nativity rates of bats are much lower than those of most other small mammals. This

is because, for the most part, only one or two pups are born per female per annum and

according to O’Shea et al. (2003), bats may live for up to 30 years, thereby limiting the number

of pups born due to this increased life expectancy. Under natural circumstances, a

population’s numbers may accumulate over long periods of time. This is due to the longevity

and the relatively low predation of bats when compared to other small mammals. Therefore,

bat populations are not able to adequately recover after mass mortalities and major roost

disturbances.

2.2 Bats and Wind Turbines

Although most bats are highly capable of advanced navigation through the use of

echolocation and excellent sight, they are still at risk of physical impact with the blades of

wind turbines. The corpses of bats have been found in close proximity to wind turbines and,

in a case study conducted by Johnson et al. (2003), were found to be directly related to

collisions. The incident of bat fatalities for migrating species has been found to be directly

related to turbine height, increasing exponentially with altitude, as this disrupts the migratory

flight paths (Howe et al. 2002, Barclay et al. 2007). Although the number of fatalities of

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migrating species increased with turbine height, this correlation was not found for increased

rotor sweep (Howe et al. 2002, Barclay et al. 2007). In the USA it was hypothesized that

migrating bats may navigate without the use of echolocation, rather using vision as their main

sense for long distance orientation (Johnson et al. 2003, Barclay et al. 2007). Despite the high

incidence of deaths caused by direct impact with the blades, most bat mortalities have been

found to be caused by barotrauma (Baerwald et al. 2008). This is a condition where low air

pressure found around the moving blades of wind turbines, causes the lungs of a bat to

collapse, resulting in fatal internal haemorrhaging (Kunz et al. 2007). Baerwald et al. (2008)

found that 90% of bat fatalities around wind turbines involved internal haemorrhaging

consistent with barotrauma. A study conducted by Arnett (2005) recorded a total of 398 and

262 bat fatalities in two surveys at the Mountaineer Wind Energy Centre in Tucker County,

West Virginia and at the Meyersdale Wind Energy Centre in Somerset County, Pennsylvania,

respectively. These surveys took place during a 6-week study period from 31 July 2004 to 13

September 2004. In some studies, such as that taken in Kewaunee County (Howe et al. 2002),

bat fatalities were found exceed bird fatalities by up to three-fold.

Although bats are predominately found roosting and foraging in areas near trees, rocky

outcrops, human dwellings and water, in conditions where valleys are foggy, warmer air is

drawn to hilltops through thermal inversion which may result in increased concentrations of

insects and consequently bats at hilltops, where wind turbines are often placed (Kunz et al.

2007). Some studies (Horn et al. 2008) suggest that bats may be attracted to the large turbine

structure as roosting spaces or that swarms of insects may get trapped in low pressure air

pockets around the turbine, also encouraging the presence of bats. The presence of lights on

wind turbines have also been identified as possible causes for increased bat fatalities for non-

cave roosting species. This is thought to be due to increased insect densities that are attracted

to the lights and subsequently encourage foraging activity of bats (Johnson et al. 2003).

Clearings around wind turbines, in previously forested areas, may also improve conditions for

insects, thereby attracting bats to the area and the swishing sound of the turbine blades has

been proposed as possible sources for disorienting bats (Kunz et al. 2007). Electromagnetic

fields generated by the turbine may also affect bats which are sensitive to magnetic fields

(Kunz et al. 2007). It could also be hypothesized, from personal observations that the

echolocation capabilities of bats are designed to locate smaller insect prey or avoid stationary

objects, and may not be primarily focused on the detection of unnatural objects moving

sideways across the flight path.

A pilot wind turbine in the Coega Industrial Development Zone, Port Elizabeth, Eastern Cape,

South Africa was surveyed for bird and bat carcasses. Over a period of one year, three surveys

per week (total 154 inspections) were performed to search for bat and bird casualties. 17 bat

fatalities and one live but injured bat was collected. Two bat species were involved, Cape

serotine (Neoromicia capensis) and Egyptian free-tailed bat (Tadarida aegyptiaca). Of the 18

casualties, 15 were recorded mid-December to mid-March. One bird, a little swift (Apus

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affinis), was hit by a rotor blade. This is the first study to document bat and bird mortalities

over the period of a year at a wind turbine in sub-Saharan Africa (Doty and Martin, 2013).

A pilot study was conducted at the Darling Wind Farm in the Western Cape to determine if

bats are being killed by wind turbines at the facility. One bat carcass was found and identified

as an adult female Neoromicia capensis. A necropsy showed that both lungs had pulmonary

haemorrhaging and had collapsed. Histological examination revealed extensive

haemorrhaging in the lungs consistent with barotrauma (Aronson et al. 2013).

Both of these South African studies point to South African bats being just as vulnerable to

mortality from turbines as international studies have previously indicated. Thus the two main

species of concern are Neoromicia capensis and Tadarida aegyptiaca.

Whatever the reason for bat fatalities in relation to wind turbines, it is clear that this is a grave

ecological problem, which requires attention. During a study by Arnett et al. (2009), 10

turbines monitored over a period of 3 months showed 124 bat fatalities in South-central

Pennsylvania (America), which can cumulatively have a catastrophic long-term effect on bat

populations if this rate of fatality continues. Most bat species only reproduce once a year,

bearing one young per female, therefore their numbers are slow to recover from mass

mortalities. It is very difficult to assess the true number of bat deaths in relation to wind

turbines, due to carcasses being removed from sites through predation, the rate of which

differs from site to site as a result of habitat type, species of predator and their numbers

(Howe et al. 2002, Johnson et al. 2003). Mitigation measures are being researched and

experimented with globally, but are still only effective on a small scale. An exception is the

implementation of curtailment processes, where the turbine cut-in speed is raised to a higher

wind speed. This relies on the principle that the prey of bats will not be found in areas of

strong winds and more energy is required for the bats to fly under these conditions. It is

thought, that by the implementation of such a measure, that bats in the area are not likely to

experience as great an impact as when the turbine blades move slowly in low wind speeds.

However, this measure is currently not effective enough to translate the impact of wind

turbines on bats to a category of low concern.

3 METHODOLOGY

Bat activity was monitored using active and passive bat monitoring techniques. Active

monitoring was carried out on site visits by the means of driven transects. A bat detector

mounted on a vehicle was used and transect routes were chosen based on road accessibility.

Sampling effort and prevalent weather conditions were recorded for each transect.

Passive detection concluded by means of a passive bat monitoring system on the

meteorological mast on site. The monitoring system consists of a SM2BAT+ time expansion

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bat detector that is powered by a 12V, 18Ah, sealed lead acid battery and a 20W solar panel

that provides recharging power to the battery. The system also has an 8-amp low voltage

protection regulator and SM3PWR step down transformer. Four SD memory cards, class 10

speed, with a capacity of 32GB each were utilized within the SM2 detector; this is to ensure

substantial memory space with high quality recordings even under conditions of multiple false

wind triggers.

Two weatherproof ultrasound SMX-US microphones were mounted at heights of 10 meters

and 80 meters on the meteorological mast. These microphones were then connected to the

SM2 bat detector. Throughout the study these microphones were replaced by SMX-U1

microphones.

The detector was set to operate in continuous trigger mode from dusk each evening until

dawn (times were correlated with latitude and longitude). Trigger mode is the setting for a

bat detector in which any frequency which exceeds 16KHz and 18dB will trigger the detector

to record for the duration of the sound and 500ms after the sound has ceased, this latter

period is known as a trigger window. All signals are recorded in WAC0 lossless compression

format.

The table below summarizes the above-mentioned equipment set up.

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3.1 Site Visit Information

Site visit dates First Visit 11 July 2016

Second Visit 12 October 2016

Third Visit 23 January 2017

Fourth Visit 25 April 2017

Fifth Visit 3 July 2017

Met mast passive bat detection systems

Amount on site 1

Microphone heights

10m and 80m

Coordinates 33°43'57.61"S 25°36'51.90"E

Replacements/ Repairs/ Comments

First Visit The microphones were mounted such that they pointed approximately 30 degrees downward to avoid excessive water damage. Measures were taken for protection against birds, without compromising effectiveness significantly. Crows have been found to peck at microphones and subsequently destroying them. The bat detector was installed within a weatherproof container and all peripherals attached.

Second Visit The SMX-US microphone on top of the mast was replaced with a SMX-U1 microphone as the old microphone was not responsive.

Third Visit The 10m microphone was replaced on the system as the old microphone was not responsive.

Fourth Visit No problems were found and all methodology were carried out.

Fifth Visit No problems were found and all methodology were carried out. The system was also decommissioned.

Type of passive bat detector SM2BAT+ Real Time Expansion (RTE) type

Recording schedule The detector was set to operate in continuous trigger mode from dusk each evening until dawn (times were automatically adjusted in relation to latitude, longitude and season).

Trigger threshold >16KHz, -18dB

Trigger window (time of recording after trigger ceased)

500ms

Microphone gain setting 48dB

Compression WAC0

Single memory card size (each systems uses 4 cards)

32GB

Battery size 18Ah; 12V

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Solar panel output 20 Watts

Solar charge regulator 6 - 8 Amp with low voltage/deep discharge protection

Other methods Terrain was investigated during the day for signs of roosting and foraging habitat.

During each site visit the passive data of the bat activity was downloaded from the monitoring

system. The data was analysed by classifying (as near to species level as possible) and counting

positive bat passes detected by the passive system. A bat pass is defined as a sequence of ≥1

echolocation calls where the duration of each pulse is ≥2ms (one echolocation call can consist

of numerous pulses). A new bat pass was identified by a >500ms period between pulses.

These bat passes were summed into hourly intervals which were used to calculate nocturnal

distribution patterns over time. Only nocturnal, dusk and dawn values of environmental

parameters from the wind data were used, as this is the only time insectivorous bats are

active. Times of sunset and sunrise were adjusted with the time of year.

In this report the bat activity is be correlated with the environmental parameters of wind

speed and air temperature, to identify optimal foraging conditions and periods of high bat

activity.

3.2 Assumptions and Limitations

Distribution maps of South African bat species still require further refinement such that the

bat species proposed to occur on the site (that were not detected) are assumed accurate. If a

species has a distribution marginal to the site, it was assumed to occur in the area. The

literature based table of species probability of occurrence may include a higher number of

bat species than actually present.

The migratory paths of bats are largely unknown, thus limiting the ability to determine if the

wind farm will have a large scale effect on migratory species. This limitation however will be

overcome with this long-term sensitivity assessment.

The satellite imagery partly used to develop the sensitivity map may be slightly imprecise due

to land changes occurring since the imagery was taken.

Species identification with the use of bat detection and echolocation is less accurate when

compared to morphological identification, nevertheless it is a very certain and accurate

indication of bat activity and their presence with no harmful effects on bats being surveyed.

It is not possible to determine actual individual bat numbers from acoustic bat activity data,

whether gathered with transects or the passive monitoring systems. However, bat passes per

night are internationally used and recognized as a comparative unit for indicating levels of bat

activity in an area.

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Spatial distribution of bats over the study area cannot be accurately determined by means of

transects, although the passive systems can provide comparative data for different areas of

the site. Transects may still possibly uncover high activity in areas where it is not necessarily

expected and thereby increase insight into the site.

Exact foraging distances from bat roosts or exact commuting pathways cannot be determined

by the current methodology. Radio telemetry tracking of tagged bats is required to provide

such information if needed.

Costly radar technology is required to provide more quantitative data on actual bat numbers

as well as spatial distribution of multiple bats.

4 RESULTS AND DISCUSSION

4.1 Land Use, Vegetation, Climate and Topography

The site is situated in three vegetation units namely Albany Alluvial Vegetation, Coega

Bontveld, and Sundays Thicket (Figure 5).

Albany Alluvial Vegetation unit is distributed within the Eastern Cape, between East London

and Cape St Francis on wide floodplains which are usually close to the coast where the

topography becomes flatter. Riverine thicket, occurring in the narrow floodplain zones in

regions close to the coast or further inland, and thornveld which are found on the wide

floodplains further inland, are the two major types of vegetation patterns within this

vegetation unit. The geology consists of underlain Jurassic-Cretaceous sediments of the

Uitenhage Group. The alluvial zones, with deposits of various textures (usually high clay

content) can become flooded following the west-east passage of frontal systems in autumn

and winter or during intensive local storms in summer. Precipitation is undifferentiated and

year-round with slight peaks in March and November, with a MAP of 350mm. The climate is

of warm-temperate, hotter in the river valleys than the surrounding landscape, while riverine

zones closer to the coast have an ameliorated climate. The Albany Alluvial vegetation unit is

Endangered, with a target of 31%. Only about 6% are statutorily conserved, while about 2%

is protected in private conservation areas. More than half of the area has been transformed

(Mucina and Rutherford 2006).

Within the Eastern Cape, north east of Port Elizabeth just inland of Algoa Bay is the vegetation

unit named the Coega Bontveld. The landscape is of moderately undulating plains, where

vegetation is a mosaic of low thicket, 2-3 m, built mainly of bush clumps. Secondary open

grassland occurs over wide stretches. This unit is an ‘island’ within a matrix of typical valley

thicket. Species are a mixture of Fynbos, Grassland and Succulent Karoo. The geology consists

of outcrops of limestone and calcareous paleo-dune fields of the Cenozoic Algoa Group.

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Shallow clay soils, often lime-rich, make up the soils of this vegetation unit. Rainfall is non-

seasonal with peaks in March and October. MAP ranges from 400mm inland in the west to

550mm in the east closer to the coast. Frost incidence is only 3 days. Maximum and minimum

temperatures for the area near Port Elizabeth is 32.1°C (February) and 3.4°C (July).

Conservation target for this vegetation unit is 19%, while 14% is protected within a National

Park and Private Nature Reserve. 6% of the unit has been altered. Erosion is moderate - low

(Mucina and Rutherford 2006).

The Sundays Thicket vegetation unit is found within the surrounds of Uitenhage and the

northern edge of Port Elizabeth. The landscape is formed by undulating plains and low

mountains and foothills covered with tall, dense thicket, where trees, shrubs and succulents

are common, with many spinescent species. The transition between lower and upper

canopies is obscured by the presence of a wide variety of lianas. The local dominance of

Portulacaria afra increases and the relative abundance of woody species present decreases

with increasing aridity. There is considerable structural heterogeneity within this vegetation

unit. The vegetation is mostly on deep (>1m) red, loamy to clayey soils derived from the

Sundays River and Kirkwood Formations (Mesozoic Uitenhage Group) in the south. Rainfall is

also non-seasonal with slight peaks in March and October/November. MAP ranges from about

190mm (northwest) to 480mm in the southeast on the coast near Port Elizabeth. Frost

incidence is 8 days. Uitenhage’s mean monthly maximum and minimum respectively is 36.9°C

(February) and 1.3°C (July). Conservation status of this vegetation unit is regarded as Least

Threatened, with a target of 19%. It is statutorily protected in National Parks, Wilderness

Areas, and private conservation areas. More than 6% is already transformed. Erosion is

moderate to very low (Mucina and Rutherford 2006).

Vegetation units and geology are of great importance as these may serve as suitable sites for

the roosting of bats and support of their foraging habits (Monadjem et al. 2010). Houses and

buildings may also serve as suitable roosting spaces (Taylor 2000; Monadjem et al. 2010). The

importance of the vegetation units and associated geomorphology serving as potential

roosting and foraging sites have been described in Table 1.

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Table 1: Potential of the vegetation to serve as suitable roosting and foraging spaces for bats.

Vegetation

Unit

Roosting

Potential

Foraging

Potential

Comments

Albany

Alluvial

Vegetation

Moderate Moderate -

High

Riverine thickets and floodplains, together with

the climate provide features to enable the

successful roosting and foraging of bat species.

Thickets will be utilised by clutter and clutter-

edge foragers.

Coega

Bontveld

Low Moderate The undulating plains with grassland and

shrubland vegetation forms provide foraging

sites for open-air foraging bat species.

Sundays

Thicket

Moderate –

High

Moderate The undulating landscape with tall dense

thickets will support bat activity. The thickets

also provide habitat for roosting purposes.

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Albany Alluvial Vegetation Coega Bontveld Sundays Thicket Figure 5: Vegetation unit present on the Scarlet Ibis site (Mucina and Rutherford 2006).

4.2 Literature Based Species Probability of Occurrence

“Probability of Occurrence” is assigned based on consideration of the presence of roosting

sites and foraging habitats on the site, compared to literature described preferences. The

probability of occurrence is indicative of the likelihood of encountering the bat species on

site.

The column of “Likely risk of impact” describes the likelihood of risk of fatality from direct

collision or barotrauma with wind turbine blades for each bat species. The risk was assigned

by Sowler et al. (2016) based on species distributions, altitudes at which they fly and distances

they traverse; and assumes a 100% probability of occurrence. The ecology of most applicable

bat species recorded in the vicinity of the site is discussed below.

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Table 2: Table of species that may be roosting or foraging on the study area, the possible site specific roosts, and their probability of occurrence based on

literature (Monadjem et al. 2010).

Species Common name

Probability of occurrence (%)

Conservation status (2016 Regional Listing)

Possible roosting habitat on site Possible foraging habitat utilised on site

Likelihood of risk of fatality (Sowler & Stoffberg, 2016)

Taphozous mauritianus

Mauritian tomb bat

50 - 60 Least Concern

Roosts on rock faces, tree trunks, and walls, where it rests its belly on the surface of the roost with its head facing down.

It is associated with savannah woodlands, preferring open habitats and avoiding closed forest interior.

High

Tadarida aegyptiaca

Egyptian free-tailed bat

Confirmed Least Concern

Roosts in rock crevices, hollows in trees, and behind the bark of dead trees. The species has also taken to roosting in roofs of buildings.

It forages over a wide range of habitats; its preferences of foraging habitat seem independent of vegetation. It seems to forage in all types of natural and urbanised habitats.

High

Miniopterus natalensis

Natal long-fingered bat

Confirmed

Near Threatened (2004 National Listing)

Cave and hollow dependent, no known caves close to site. Will also roost in small groups or individually in culverts and other hollows.

Clutter-edge forager. May forage in more open terrain during suitable weather.

Medium - High

Miniopterus fraterculus

Lesser long-fingered bat

50 - 60 Near Threatened (2004 National Listing)


Clutter-edge forager. May forage in more open terrain during suitable weather.

Medium-High

Kerivoula lanosa Lesser woolly bat 20 - 30


Has been found roosting in weaver and sunbird nests.

Very little information is available on the preferred habitat.

Low

Eptesicus hottentotus

Long-tailed serotine

Confirmed Least Concern It is a crevice dweller roosting in rock crevices, as well as other crevices in buildings.

It seems to prefer woodland habitats, and forages on the clutter edge.

Medium

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Myotis tricolor Temmink’s myotis Confirmed



A clutter-edge forager that feeds on aerial prey such as Coleoptera, Hemiptera, Diptera, Neuroptera and Hymenoptera.

Medium - High

Neoromicia capensis

Cape serotine Confirmed Least Concern Roosts under the bark of trees and under the roofs of houses.

It appears to tolerate a wide range of environmental conditions from arid semi-desert areas to montane grasslands, forests, and savannahs.

Medium - High

Pipistrellus hesperidus

Dusky pipistrelle Confirmed Least Concern

Its roosting habits are poorly known in southern Africa. May utilise cracks in rocks and under the loose bark of dead trees.

Well-wooded locations such as riparian vegetation and forest patches, especially in the proximity of water. Clutter edge forager.

Medium

Scotophilus dinganii

Yellow-bellied house bat

Confirmed Least Concern Roosts in hollow spaces in the roofs of buildings and hollows in large trees.

Preferred habitat appears to be associated with presence of trees; it is absent from open habitat. Forages around edges of clutter vegetation.

Medium - High

Rousettus aegyptiacus

Egyptian rousette (fruit bat)

10 - 20 Least Concern Cave or mine dependent, no known caves in the immediate area. May utilise man made hollows.

Feeds on fruit, nectar, pollen and flowers. It is known to travel several kilometres to reach fruiting trees and have a primitive form of echolocation.

Medium-High

Rhinolophus capensis

Cape horseshoe bat

40 - 50


Roosts in caves and mine adits, no known caves in the immediate area. May utilise man made hollows.

Forages predominantly in the canopy of trees.

Low

Rhinolophus clivosus

Geoffroy’s horseshoe bat

70 - 80


Roosts in caves and mine adits, no known caves in the immediate area. May utilise man made hollows.

It is associated with a variety of habitats including thickets.

Low

Nycteris thebaica Egyptian slit-faced bat

40 - 50 Least Concern Roosts in hollows, culverts under roads and the trunks of large trees.

It appears to occur throughout the savannah and karoo biomes, but avoids open grasslands. May occur in the thickets.

Low

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4.3 Ecology of bat species that may be largely impacted by the Scarlet Ibis WEF

There are several bat species in the vicinity of the site that occur commonly in the area. These

species are of importance based on their likelihood of being impacted by the proposed WEF,

due to high abundances and certain behavioural traits. The relevant species are discussed

below.

Tadarida aegyptiaca

The Egyptian Free-tailed Bat, Tadarida aegyptiaca, is a Least Concern species (IUCN Red List

2016) as it has a wide distribution and high abundance throughout South Africa, and is part

of the Free-tailed bat family (Molossidae). It occurs from the Western Cape of South Africa,

north through to Namibia and southern Angola; and through Zimbabwe to central and

northern Mozambique (Monadjem et al. 2010). This species is protected by national

legislation in South Africa (ACR 2010).

They roost communally in small (dozens) to medium-sized (hundreds) groups in caves, rock

crevices, under exfoliating rocks, in hollow trees and behind the bark of dead trees. Tadarida

aegyptiaca has also adapted to roosting in buildings, in particular roofs of houses (Monadjem

et al. 2010). Thus man-made structures and large trees on the site would be important roosts

for this species.

Tadarida aegyptiaca forages over a wide range of habitats, flying above the vegetation

canopy. It appears that the vegetation has little influence on foraging behaviour as the species

forages over desert, semi-arid scrub, savannah, grassland and agricultural lands. Its presence

is strongly associated with permanent water bodies due to concentrated densities of insect

prey (Monadjem et al. 2010).

The Egyptian Free-tailed bat is considered to have a High likelihood of risk of fatality due to

wind turbines (Sowler et al. 2016). Due to the high abundance and widespread distribution of

this species, high mortality rates due to wind turbines would be a cause of concern as these

species have more significant ecological roles than the rarer bat species.

After a gestation of four months, a single young is born, usually in November or December,

when females give birth once a year. In males, spermatogenesis occurs from February to July

and mating occurs in August. Maternity colonies are apparently established by females in

November.

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Neoromicia capensis

Neoromicia capensis is commonly called the Cape serotine and has a conservation status of

Least Concern (IUCN Red List 2016) as it is found in high numbers and is widespread over

much of Sub-Saharan Africa.

High mortality rates of this species due to wind turbines would be a cause of concern as N.

capensis is abundant and widespread and as such has a more significant role to play within

the local ecosystem than the rarer bat species. They do not undertake migrations and thus

are considered residents of the site.

It roosts individually or in small groups of two to three bats in a variety of shelters, such as

under the bark of trees, at the base of aloe leaves, and under the roofs of houses. They will

use most man-made structures as day roosts which can be found throughout the site and

surrounding areas (Monadjem et al. 2010).

They are tolerant of a wide range of environmental conditions as they survive and prosper

within arid semi-desert areas to montane grasslands, forests, and savannas; indicating that

they may occupy several habitat types across the site, and are amenable towards habitat

changes. They are however clutter-edge foragers, meaning they prefer to hunt on the edge

of vegetation clutter mostly, but can occasionally forage in open spaces. They are thought to

have a Medium-High likelihood of risk of fatality due to wind turbines (Sowler et al. 2016).

Mating takes place from the end of March until the beginning of April. Spermatozoa are

stored in the uterine horns of the female from April until August, when ovulation and

fertilisation occurs. They give birth to twins during late October and November but single

pups, triplets and quadruplets have also been recorded (van der Merwe 1994 and Lynch

1989).

Miniopterus natalensis

Miniopterus natalensis, also commonly referred to as the Natal long-fingered bat, occurs

widely across the country but mostly within the southern and eastern regions and is listed as

Near Threatened (Monadjem et al. 2010). This bat is a cave-dependent species and

identification of suitable roosting sites may be more important in determining its presence in

an area than the presence of surrounding vegetation. It occurs in large numbers when

roosting in caves with approximately 260 000 bats observed making seasonal use of the De

Hoop Guano Cave in the Western Cape, South Africa. Culverts and mines have also been

observed as roosting sites for either single bats or small colonies. Separate roosting sites are

used for winter hibernation activities and summer maternity behaviour, with the winter

hibernacula generally occurring at higher altitudes in more temperate areas and the summer

hibernacula occurring at lower altitudes in warmer areas of the country (Monadjem et al.

2010)

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Mating and fertilisation usually occur during March and April and is followed by a period of

delayed implantation until July/August. Birth of a single pup usually occurs between October

and December as the females congregate at maternity roosts (Monadjem et al. 2010 & Van

Der Merwe 1979).

The Natal long-fingered bat undertakes short migratory journeys between hibernaculum and

maternity roosts. Due to this migratory behaviour, they are considered to be at high risk of

fatality from wind turbines if a wind farm is placed within a migratory path (Sowler et al.

2016). The mass movement of bats during migratory periods could result in mass casualties if

wind turbines are positioned over a mass migratory route and such turbines are not

effectively mitigated. Very little is known about the migratory behaviour and paths of M.

natalensis in South Africa with migration distances exceeding 150 kilometres. If the site is

located within a migratory path the bat detection systems should detect high numbers and

activity of the Natal long-fingered bat. This will be examined over the course of the 12-month

monitoring survey.

A study by Vincent et al. (2011) on the activity and foraging habitats of Miniopteridae found

that the individual home ranges of lactating females were significantly larger than that of

pregnant females. It was also found that the bats predominately made use of urban areas

(54%) followed by open areas (19.8%), woodlands (15.5%) orchards and parks (9.1%) and

water bodies (1.5%) when selecting habitats. Foraging areas were also investigated with the

majority again occurring in urban areas (46%), however a lot of foraging also occurred in

woodland areas (22%), crop and vineyard areas (8%), pastures, meadows and scrubland (4%)

and water bodies (4%).

Sowler et al. (2016) advise that M. natalensis faces a medium to high risk of fatality due to

wind turbines. This evaluation was based on broad ecological features and excluded

migratory information.

4.4 Transects

Transects were not carried out over the first site visit. Driven transects were carried out over

the following site visits, with one additional transect still to be carried out on the last site visit

4.4.1 Second Site Visit

Figure 6 - 7 below indicates the transect routes during the second site visit. Transect routes

were not calculated and were carried out randomly based on available access to the farms

and condition of the farm roads. The SM2BAT+ Real time expansion type detector was used.

Table 3 displays the sampling effort and weather conditions prevalent during transect survey.

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Table 3: Transect distance, duration and average weather conditions experienced during the second

site visit.

Date Time started

Distance (km)

Duration (hours and minutes)

Temperature (˚C)

Rain (mm)

Wind speed (km/h)

12 October 2016 18:19 20.75 3hr 00 min 17 0.0 28.96

Very few bat passes and only one bat species, Tadarida aegyptiaca, was recorded (Figure 6-7).

The low amount of bat passes can be attributed to high wind speeds on site.

Tadarida aegyptiaca Transect tracks

Figure 6: Transect routes and bat passes recorded across the southern half of the site over the second

site visit.

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Figure 7: Transect routes and bat passes recorded across the northern half of the site over the second

site visit.

4.4.2 Third Site Visit

Figure 8 - 9 below indicates the transect routes during the third site visit. Transect routes

were not calculated and were carried out randomly based on available access to the farms

and condition of the farm roads. The SM2BAT+ Real time expansion type detector was used.

Table 4: Transect distance, duration and average weather conditions experienced during the third

site visit

Date Time started

Distance (km)

Duration Temperature (˚C)

Rain (mm)

Wind speed (km/h)

23 January 2017 18:19 22.27 1hr 25 min 27 0.0 6.4

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A higher number of bat passes were recorded during the second transects which could be

because of higher temperatures and low wind speed having a positive effect on active

foraging of bats.

Tadarida aegyptiaca Neoromicia capensis Transect tracks

Figure 8: Transect routes and bat passes recorded across the southern half of the site over the third

site visit.

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Figure 9: Transect routes and bat passes recorded across the northern half of the site over the third

site visit.

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4.4.3 Fourth Site Visit

Figures 10 - 11 below indicates the transect routes during the fourth site visit. Transect routes

were not calculated and were carried out randomly based on available access to the farms and

condition of the farm roads. The SM2BAT+ Real time expansion type detector was used.

Table 5: Transect distance, duration and average weather conditions experienced during the fourth

site visit.

Date Time started

Distance (km)


Rain (mm) Wind speed (km/h)

25 April 2017 18:10 30.1 2hr 58 min 19.5 0.0 9.6

The number of bat passes recorded during the third transect and fourth site visit (Figures 10-

11) show a higher activity than that recorded on the first transect (Figures 6-7) but fewer bat

passes were recorded than on the second transect (Figures 8-9). Weather conditions on this

day, cool temperatures and moderate winds, may be less favourable. Bats prefer foraging in

low wind conditions, furthermore the low temperatures recorded (Table 5) is likely to

negatively affect the abundance of their preferred insect prey (Peng 1991). Two species were

recorded namely, Tadarida aegyptiaca and Neoromicia capensis, with a higher number of bat

passes from T. aegyptiaca.

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Figure 10: Transect routes and bat passes recorded across the southern half of the site over the

fourth site visit.

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Figure 11: Transect routes and bat passes recorded across the northern half of the site over the fourth

site visit.

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4.4.4 Fifth Site Visit

Figure 12 below indicates the transect route during the fifth site visit. The SM2BAT+ Real time

expansion type detector was used.

Table 6: Transect distance, duration and average weather conditions experienced during the fifth

site visit.

Date Time started

Distance (km)


Rain (mm) Wind speed (km/h)

3 July 2017 18:17 18 1hr 24 min 14 0.0 11.2

The number of bat passes recorded during the fifth transect were very low as expected during

the colder winter months. Only one species was recorded, the Egyptian Free-Tailed bat

(Tadarida aegyptiaca).

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Figure 12: Transect route and bat passes recorded across the site over the fifth site visit.

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4.5 Sensitivity Map

Figures 13 - 15 depicts the sensitive areas of the site, based on features identified to be

important for foraging and roosting of the species that are most probable to occur on site.

Thus, the sensitivity map is based on species ecology and habitat preferences. This map can

be used as a pre-construction mitigation in terms of improving turbine placement with regards

to bat preferred habitats on site.

Table 6: Description of parameters used in the construction of a sensitivity map.

Last iteration June 2017

High sensitivity buffer 200m radial buffer

Moderate sensitivity buffer 50m radial buffer

Features used to develop the sensitivity map

Manmade structures, such as buildings, houses, barns, sheds or road culverts, these structures provide easily accessible roosting sites.

The presence of probable hollows/overhangs, rock faces or clumps of larger woody plants. These features provide natural roosting spaces and tend to attract insect prey.

The different vegetation types and presence of riparian/water drainage habitat is used as indicators of probable foraging areas.

Open water sources, be it man-made farm dams or natural streams and wetlands, are important sources of drinking water and provide habitat that host insect prey.

Table 7: Description of sensitivity categories utilized in the sensitivity map.

Sensitivity Description

Moderate Sensitivity

Areas of foraging habitat or roosting sites considered to have

significant roles for bat ecology. Turbines within or close to

these areas must acquire priority (not excluding all other

turbines) during pre/post-construction studies, and mitigation

measures may need to be applied to them.

High Sensitivity

Areas that are deemed critical for resident bat populations,

capable of elevated levels of bat activity and support greater

bat diversity than the rest of the site. These areas are ‘no-go’

areas and turbines must not be placed in these areas and their

buffers.

No wind turbines fall within areas or buffers of moderate or high bat sensitivities, and therefore

the current proposed layout is acceptable.

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High bat sensitivity area High bat sensitivity buffer (200m)

Moderate bat sensitivity area Moderate bat sensitivity buffer (50m)

Figure 13: Bat sensitivity map of the Scarlet Ibis WEF site showing moderate and high sensitivity zones

and their buffers.

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Figure 14: Bat sensitivity map of the northern Scarlet Ibis wind turbines showing moderate and high

sensitivity zones and their buffers.

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Figure 15: Bat sensitivity map of the southern Scarlet Ibis wind turbines showing moderate and high

sensitivity zones and their buffers.

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4.6 Passive Data

4.6.1 Abundances and Composition of Bat Assemblages

Seven bat species were detected namely Eptesicus hottentotus, Miniopterus natalensis,

Neoromicia capensis, Tadarida aegyptiaca, Scotophilus dinganii, Pipistrellus hesperidus and Myotis

tricolor. The total number of bat passes detected over the entire monitoring period (11 July 2016

– 3 July 2017) by the system and the average hourly bat passes detected per month (activity index)

are displayed in Figures 16 - 17. Activity indexes are calculated for nights on which the detector

recorded correctly.

Neoromicia capensis and Tadarida aegyptiaca were most commonly detected by the monitoring

system. Although both species have a conservation status of least concern, these abundant species

are of a large value to the local ecosystems as they provide a greater contribution to most

ecological services than the rarer species due to their higher numbers.

The monitoring system detected the migratory species, Miniopterus natalensis, however it has

been detected with a relatively low activity index and mostly at the height of 10 m above the

ground. Myotis tricolor is also a seasonal migratory species which was detected by the 10m height

bat detector in relatively low numbers over the months of February to May 2017. These activity

patterns do not indicate any significant migratory events.

The bat activity data collected displays a seasonal trend of low bat activity over the winter months

of May to August. Overall peak activity has been found to be highest over the summer months of

December 2016 and the Autmun month of April (Figure 17), this is particularly considering activy

of T. aegyptiaca at 80m which is most applicable to the rotor swept zone.

Bat activity is showing to be approximately three times higher at the monitoring height of 10m

above the ground than 80m above the ground (Figure 16). This is most likely due to the harsher

wind and temperature conditions experienced at a greater elevation above the ground and

subsequently less insect prey in such conditions. T. aegyptiaca is the only species recorded on site

that shows higher activity at a monitoring height of 80m above ground level, this is to be expected

as it is an open-air forager and is also therefore more likely to be affected by the rotor swept zone.

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Figure 16: Total bat passes recorded over the entire monitoring period by the detector mounted on the Met Mast.

202 150

8208

2456

95 5 93 11 5 133

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Total bat passes per species and height- Met Mast

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Figure 17: Average hourly bat passes recorded per month by the detector mounted on the Met Mast.

0.13

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Ave

rage

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Monitoring period

Average hourly bat passes per month - Met Mast

Eptesicus hottentotus 10m Miniopterus natalensis 10m Neoromicia capensis 10m Tadarida aegyptiaca 10m

Eptesicus hottentotus 80m Miniopterus natalensis 80m Neoromicia capensis 80m Tadarida aegyptiaca 80m

Scotophilus dinganii 10m Pipistrellus hesperidus 10m Myotis tricolor 10m Scotophilus dinganii 80m

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4.6.2 Temporal Distribution

Figure 18 displays the sum of all species-specific bat passes recorded per night over the entire

monitoring period (11 July 2016 – 3 July 2017). The temporal distribution of bat passes was also

summed hourly for each species and graphically displayed for each calendar season (Figures 19-

22). Together the graphs provide an indication of the specific date periods and times across the

night where high activity was highest by each monitoring system for each species and season.

Two larger peaks of activity from T. aegyptiaca at 80m can be seen in December 2016 and April

2017 (Figure 18).

For the distribution of bat activity across the night, per season (Figures 19 – 22), the 12-month

monitoring period was divided based on generic calendar seasons outlined in Table 8.

Table 8: Time frame of each season

Season Monitoring period

Spring 1 September – 30 November

Summer 1 December – 28 February

Autumn 1 March – 31 May

Winter 1 June – 31 August

During summer, the peak activity of T. aegyptiaca at 80m was from 20:00 – 21:00 and gradually

declining towards 00:00 (Figure 20). For Autumn, the peak activity of T. aegyptiaca at 80m was

from 19:00 – 21:00 and gradually declining towards 03:00 (Figure 21).

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Figure 18: Nightly temporal distribution of all species-specific bat passes recorded over the entire monitoring period at the Met Mast.

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Temopral distribution per date - Met Mast

Eptesicus hottentotus 10m Miniopterus natalensis 10m Eptesicus hottentotus 80m Neoromicia capensis 80m

Scotophilus dinganii 10m Pipistrellus hesperidus 10m Myotis tricolor 10m Scotophilus dinganii 80m

Miniopterus natalensis 80m Tadarida aegyptiaca 10m Tadarida aegyptiaca 80m Neoromicia capensis 10m

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Figure 19: Time of night activity for the spring season recorded at the Met Mast.

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Spring temporal distribution per hour - Met Mast

Miniopterus natalensis 80m Neoromicia capensis 80m Eptesicus hottentotus 10m Miniopterus natalensis 10m

Tadarida aegyptiaca 10m Tadarida aegyptiaca 80m Neoromicia capensis 10m

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Figure 20: Time of night activity for the summer season recorded at the Met Mast.

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Summer temporal distribution per hour - Met Mast

Scotophilus dinganii 80m Scotophilus dinganii 10m Myotis tricolor 10m Eptesicus hottentotus 80m

Pipistrellus hesperidus 10m Neoromicia capensis 80m Eptesicus hottentotus 10m Miniopterus natalensis 10m


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Figure 21: Time of night activity for the autumn season recorded at the Met Mast.

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:00

23

:00

:00

00

:00

:00

01

:00

:00

02

:00

:00

03

:00

:00

04

:00

:00

05

:00

:00

06

:00

:00

Sum

of

bat

pas

ses

per

ho

ur

Time of the night

Autumn temporal distribution per hour - Met Mast

Scotophilus dinganii 80m Scotophilus dinganii 10m Myotis tricolor 10m Eptesicus hottentotus 80m

Pipistrellus hesperidus 10m Eptesicus hottentotus 10m Miniopterus natalensis 10m Neoromicia capensis 80m


of 76

Figure 22: Time of night activity for the winter season recorded at the Met Mast.

0

50

100

150

200

250

300

17

:00

:00

18

:00

:00

19

:00

:00

20

:00

:00

21

:00

:00

22

:00

:00

23

:00

:00

00

:00

:00

01

:00

:00

02

:00

:00

03

:00

:00

04

:00

:00

05

:00

:00

Sum

of

bat

pas

ses

per

ho

ur

Time of the night

Winter temporal distribution per hour - Met Mast

Scotophilus dinganii 10m Eptesicus hottentotus 10m Miniopterus natalensis 10m


of 76

4.6.3 Relation between Bat Activity and Weather Conditions

Several sources of literature describe how numerous bat species are influenced by weather

conditions (O’Farrell et al. 1967, Rachwald 1992, Arnett et al. 2010). Weather may influence

bats in terms of lowering activity, changing time of emergence and flight time. It is also

important to note the environmental factors are never isolated and therefore a combination

of the environmental factors can have synergistic or otherwise contradictory influences on bat

activity. For example, a combination of high temperatures and low wind speeds will be more

favourable to bat activity than low temperatures and low wind speed, whereas low

temperature and high wind speed will be the least favourable for bats. Below are short

descriptions of how wind speed, temperature and barometric pressure influences bat activity.

Wind speed

Some bat species show reduced activity in windy conditions. Strong winds have been found

to suppress flight activity in bats by making flight difficult (O’Farrell et al. 1967). Several studies

at proposed and operating wind facilities in the United States have documented discernibly

lower bat activity during ‘high’ wind speeds (Arnett et al. 2010).

Wind speed and direction also affects availability of insect prey as insects on the wing often

accumulate on the lee side of wind breaks such as tree lines (Peng et al. 1992). At edges

exposed to wind, flight activity of insects, and thus bats may be suppressed and at edges to

the lee side of wind, bat activity may be greater. This relationship is used in the sensitivity map

whereby the larger vegetation and man-made structures provide shelter from the wind.

However, the turbine localities are usually situated on the ridges such that they will be in areas

exposed to the wind and not protected by vegetation or structure.

Temperature

Flight activity of bats generally increases with temperature. Flights are of shorter duration on

cooler nights and extended on warmer nights. Rachwald (1992) noted that distinct peaks of

activity disappeared in warm weather such that activity was mostly continuous through the

night. During nights of low temperatures bats intensified foraging shortly after sunset (Corbet

and Harris 1991).

Peng (1991) found that many families of aerial dipteran (flies) insects preferred warm

conditions for flight. A preference among insects for warm conditions has been reported by

many authors suggesting that temperature is an important regulator of bat activity, through

its effects on insect prey availability.

of 76

The aim of this analysis is to determine the wind speed and temperature range within which

80% of bat passes were detected (Figures 24 – 34). These values of wind speed and

temperature may be used, if necessary, to inform mitigation measures for turbines based on

conserving 80% of detected bat passes. This is keeping in mind the synergistic or otherwise

contradictory effects that the combination of wind speeds and temperatures can have on bat

activity.

During the period of 15 – 31 Dec 2016, 80% of bat passes were detected above temperatures

of 20°C and below wind speeds of 7.5m/s (normalised data in Figures 25 and 28). During the

period of 1 - 30 April 2017, 80% of bat passes were detected above temperatures of 19°C and

below wind speeds of 10m/s (normalised data in Figures 31 and 34).

of 76



0

50

100

150

200

250

16

.5-<

17

.0

17

.0-<

17

.5

17

.5-<

18

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23

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24

.0

24

.0-<

24

.5

No

n-N

orm

alis

ed B

at P

asse

s

Temperature 80m (°C)

Temp: Met mast 15 - 31 Dec 2016

0.001.002.003.004.005.006.007.00

16

.0-<

16

.5

16

.5-<

17

.0

17

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17

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17

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18

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18

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24

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24

.5-<

25

.0

No

rmal

ised

Bat

Pas

ses


Temp: Met mast 15 - 31 Dec 2016

of 76


0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

16

.5-<

17

.0

17

.0-<

17

.5

17

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18

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23

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24

.0

24

.0-<

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Cu

mu

lati

ve p

erc

en

tage

of

bat

pas

ses


Temp: Met mast 15 - 31 Dec 2016 Non-normalised Normalised

of 76



050

100150200250

0.0

–<0

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0.5

–<1

.0

1.0

–<1

.5

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.0

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11

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.0

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No

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orm

alis

ed

Bat

Pas

ses

Wind Speed 80m (m/s)

Wind: Met mast 15 - 31 Dec 2016

0.00

1.00

2.00

3.00

4.00

0.0

–<0

.5

0.5

–<1

.0

1.0

–<1

.5

1.5

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.0

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–<2

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2.5

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.0

3.0

–<3

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No

rmal

ise

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asse

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of 76


0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0.0

–<0

.5

0.5

–<1

.0

1.0

–<1

.5

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–<2

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Non-normalised Normalised

of 76



050

100150200250300

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27

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No

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alis

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at P

asse

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Temp: Met Mast 1 - 30 Apr 2017

0.001.002.003.004.005.006.007.008.00

10

.0–<

10

.51

0.5

–<1

1.0

11

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7.0

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8.0

No

rmal

ised

Bat

Pas

ses


Temp: Met mast 1 - 30 Apr 2017

of 76


0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%1

1.0

–<1

1.5

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Temp: Met mast 1 - 30 Apr 2017 Non-normalised Normalised

of 76



050

100150200250300350400

0.0

–<0

.50

.5–<

1.0

1.0

–<1

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.5–<

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2.0

–<2

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3.0

3.0

–<3

.53

.5–<

4.0

4.0

–<4

.54

,5–<

5.0

5.0

–<5

.55

.5–<

6.0

6.0

–<6

.56

.5–<

7.0

7.0

–<7

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.5–<

8.0

8.0

–<8

.58

.5–<

9.0

9.0

–<9

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.5–<

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Bat

Pas

ses


Wind: Met mast 1 - 30 Apr 2017

0.000.501.001.502.002.503.00

0.0

–<0

.50

.5–<

1.0

1.0

–<1

.51

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–<2

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3.0

3.0

–<3

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.5–<

4.0

4.0

–<4

.54

,5–<

5.0

5.0

–<5

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.5–<

6.0

6.0

–<6

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.5–<

7.0

7.0

–<7

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.5–<

8.0

8.0

–<8

.58

.5–<

9.0

9.0

–<9

.59

.5–<

10

.01

0.0

–<1

0.5

10

.5–<

11

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1.0

–<1

1.5

11

.5–<

12

.01

2.0

–<1

2.5

12

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13

.01

3.0

–<1

3.5

13

.5–<

14

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4.0

–<1

4.5

14

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15

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16

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6.5

No

rmal

ise

d B

at P

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of 76


0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%0

.0–<

0.5

0.5

–<1

.0

1.0

–<1

.5

1.5

–<2

.0

2.0

–<2

.5

2.5

–<3

.0

3.0

–<3

.5

3.5

–<4

.0

4.0

–<4

.5

4,5

–<5

.0

5.0

–<5

.5

5.5

–<6

.0

6.0

–<6

.5

6.5

–<7

.0

7.0

–<7

.5

7.5

–<8

.0

8.0

–<8

.5

8.5

–<9

.0

9.0

–<9

.5

9.5

–<1

0.0

10

.0–<

10

.5

10

.5–<

11

.0

11

.0–<

11

.5

11

.5–<

12

.0

12

.0–<

12

.5

12

.5–<

13

.0

13

.0–<

13

.5

13

.5–<

14

.0

14

.0–<

14

.5

14

.5–<

15

.0

15

.0–<

15

.5

15

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16

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16

.5

Cu

mu

lati

ve p

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tage

of

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pas

ses



Non-normalised Normalised

of 76

5 IMPACT ASSESSMENT OF THE PROPOSED WEF ON BAT FAUNA

5.1 Construction phase

5.1.1 Impact: Loss of foraging habitat

Cause and Comment

Loss of foraging habitat. Some minimal foraging habitat will be permanently lost by

construction of turbines and access roads. Temporary foraging habitat loss will occur during

construction due to storage areas and movement of heavy vehicles.

Mitigation Measures

Keep to designated areas when storing building materials, turbine components and/or

construction vehicles and keep to designated roads with all construction vehicles. Damaged

areas after construction should be rehabilitated by a vegetation succession specialist.

Significance Statement (Nature, significance and consequence of impact)

Insect prey of bats rely on the natural vegetation structures.

IMPACT 1: Loss of foraging habitat

IMPACT

EFFECT RISK OR

LIKELIHOOD

OVERALL

SIGNIFICANCE TEMPORAL

SCALE

SPATIAL

SCALE

SEVERITY OF

IMPACT

Without

Mitigation Long Term Localised Slight Definite LOW -

With

Mitigation Long Term Localised Slight Definite LOW -

No-Go

Alternative Long Term Study Area

Moderately

beneficial Definite LOW +

Cumulative Long Term Study Area Moderately

severe Definite MODERATE -

Can the impact be reversed? Yes, by means of vegetation rehabilitation after

decommissioning.

Will the impact cause an irreplaceable loss of

resources?

No.

Overall Cumulative Impact Statement:

Even when considered cumulatively the impact only

have a moderate significance, since the percentage of

land area transformed is minimal and turbines are

spaced relatively far from each other in terms of bat

foraging habitat.

of 76

5.2 Operational phase

5.2.1 Impact: Bat mortalities due to direct blade impact or barotrauma during foraging

activities

Cause and Comment

Bat mortalities due to direct blade impact or barotrauma during foraging activities. The

concerns of foraging bats in relation to wind turbines is discussed in Section 2.2.

Mitigation Measures

Adhere to the sensitivity maps, avoid areas of high bat sensitivity and their buffers as well as

preferably avoid areas of Moderate bat sensitivity and their buffers (this has already been

achieved by the proposed development). Adhere to recommended operational mitigation

measures detailed in Section 7.


If the impact is too severe (e.g. in the case of no mitigation) local bat populations may not

recover from mortalities easily.

IMPACT 2: Bat mortalities due to blade impact or barotrauma

IMPACT

EFFECT RISK OR

LIKELIHOOD

OVERALL


SCALE

SPATIAL

SCALE

SEVERITY OF

IMPACT

Without

Mitigation Long Term Study Area Severe Definite HIGH -

With

Mitigation Long Term Study Area

Moderately

severe Possible MODERATE -

No-Go

Alternative Long Term Study Area Beneficial Definite BENEFICIAL +

Cumulative Long Term Study Area Severe Probable MODERATE -

Can the impact be reversed?

The impact will occur throughout the lifespan of the

wind facility, therefore population numbers may take

very long to recover. Population and diversity genetics

may be (but not necessarily) permanently altered.


resources?

Yes, if population and diversity genetics are altered

over time.


If all other facilities in the area adheres to their

respective sensitivity maps and recommended

mitigation measures, the cumulative impact will be

lowered significantly.

of 76

5.2.2 Impact: Increased likelihood of bat mortalities due to artificial lighting

Cause and Comment

During operation, strong artificial lights that may be used at the turbine base or immediate

surrounding infrastructure will attract insects and thereby also bats. This will significantly

increase the likelihood of blade impact on bats foraging around such lights. Additionally, only

certain species of bats will readily forage around strong lights, whereas others avoid such

lights even if there are insect prey available, which can draw insect prey away from other

natural areas and thereby artificially favour only certain species.

Mitigation Measures

Strive to utilise lights with wavelengths that attract less insects (low thermal/infrared and UV

signatures). Lights should be switched off when not in use or must be equipped with passive

motion sensors which can assist in security measures.


Bat mortalities due to blade impact may increase significantly if bats are drawn to forage

around lights at turbine bases. Bat species diversities may be altered when only certain

species of bats are favoured by the increased food resources around artificial lights.

IMPACT 3: Increased likelihood of bat mortalities due to artificial lighting

IMPACT

EFFECT RISK OR

LIKELIHOOD

OVERALL


SCALE

SPATIAL

SCALE

SEVERITY OF

IMPACT

Without

Mitigation Long Term Study Area Severe Probable MODERATE -

With

Mitigation Long Term Localised Slightly severe Unlikely LOW -

No-Go

Alternative Long Term Study Area Beneficial Definite BENEFICIAL +

Cumulative Long Term Study Area Severe Probable HIGH -

Can the impact be reversed?

If the impact persists without mitigation over the long

term, the population numbers may take very long to

recover. If the impact is mitigated within a short time

period the reversibility is very high.


resources?

Yes, if population and diversity genetics are altered

over time (only if the impact persists over a long time)

Overall Cumulative Impact Statement: If artificial lighting is occurring at many turbines in the

area, the overall cumulative likelihood of mortalities

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due to blade impact will increase significantly for the

area and can have severe consequences on bat

populations if the impact persists over a long time.

Additionally, photophobic (light avoiding) species will

move out of the area for as long as the impact

remains.

5.3 Decommissioning phase

5.3.1 Impact: Temporary loss of foraging habitat

Cause and Comment

Minimal temporary foraging habitat loss may occur during decommissioning due to storage

areas and movement of heavy vehicles.

Mitigation Measures

Keep to designated areas when storing turbine components and/or construction vehicles and

keep to designated roads with all construction vehicles. Damaged areas after

decommissioning should be rehabilitated by allowed to recover naturally.


Insect prey of bats rely on the natural vegetation.

IMPACT 1: Temporary loss of foraging habitat

IMPACT

EFFECT RISK OR

LIKELIHOOD

OVERALL


SCALE

SPATIAL

SCALE

SEVERITY OF

IMPACT

Without

Mitigation Short term Localised Slight Possible LOW -

With

Mitigation Short term Localised Slight Possible LOW -

No-Go

Alternative Long Term Localised Slight Definite LOW +

Cumulative Short term Study Area No effect Unlikely NO

SIGNIFICANCE

Can the impact be reversed? Yes, by means of vegetation rehabilitation after

decommissioning.

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resources?

No.


This impact does not have a significant cumulative

impact, since decommissioning of the nearby wind

farms will not all occur at the same time.

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6 CUMULATIVE IMPACT ASSESSMENT

Four other renewable energy development applications have been authorized within the area

of the proposed Scarlet Ibis WEF. These are displayed in Figure 35 below, namely Dassiesridge

WEF, Grassridge WEF, Ukomeleza WEF and Motherwell WEF. The bat sensitivity assessment

reports were obtained for these wind energy developments and their sensitivity maps and/or

recommended mitigation measures were considered.

Ukomeleza WEF Grassridge WEF Proposed Scarlet Ibis WEF

Dassiesridge WEF Motherwell WEF

Figure 35: Approved renewable energy developments in a 25km radius of the proposed Scarlet Ibis

WEF site.

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The main impact on bats that raises concern from a cumulative impact assessment point of

view is the bat mortalities due to direct turbine blade collision or barotrauma during

operation. Mortalities of bats due to wind turbines during foraging and migration can have

significant ecological consequences as the bat species at risk are insectivorous and thereby

contribute significantly to the control of nocturnal flying insects. If such an impact is present

on multiple wind farms in close vicinity of each other, insect numbers can increase regionally

and possibly cause outbreaks of colonies of certain insect species.

Figure 36 below displays bat sensitivity maps of the Dassiesridge WEF, Grassridge WEF,

Ukomeleza WEF and Motherwell wind farms near the proposed Scarlet Ibis WEF. The bat

sensitivity maps were inspected for congruency of sensitive areas and similarities in their

buffer distances. The sensitivity map of the Scarlet Ibis WEF is sufficient and consistent when

assessed with nearby site sensitivity maps, and the nearby sites turbine layout adhered to

their respective sensitivity maps.

The sensitivity maps were also used to assess whether the Scarlet Ibis WEF turbine layout

intersects interlinking bat sensitivity habitats between the different sites i.e. valley areas,

rivers and streams, mountain ridges. The Scarlet Ibis WEF turbine layout does not traverse

large scale ecological corridors or ecological areas of connectivity. Thus, the existing bat

sensitivity map is sufficient in this regard.

The final pre-construction bat monitoring reports of the Dassiesridge WEF, Grassridge WEF,

Ukomeleza WEF and Motherwell wind energy facilities each identify peak bat activity periods

with some similarities to that of the proposed Scarlet Ibis WEF peak bat activity periods. Such

similarities point to a large-scale trend in bat activity across the greater area.

The most effective mitigation measures from a cumulative point of view can be achieved

when all WEF’s in the area adhere to their respective recommended mitigation measures and

sensitivity maps. That will subsequently create safe zones and corridors for bats on a spatial

and temporal scale.

Mitigation curtailment is already currently being applied at the Grassridge WEF.

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High bat sensitivity area High bat sensitivity buffer

Moderate bat sensitivity area Moderate bat sensitivity buffer

Figure 36: Bat sensitivity maps of wind farm areas near the proposed Scarlet Ibis WEF (red turbine

positions in far south of map).

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7 PROPOSED MITIGATION MEASURES AND DETAILS

The correct placement of wind farms and of individual turbines can significantly lessen the

impacts on bat fauna in an area, and should be considered as the preferred initial layer for

mitigation.

Additional to mitigation by location, other options that may be utilized include curtailment,

blade feathering, blade lock, acoustic deterrents or light lures. The following terminology

applies:

Curtailment:

Curtailment is defined as the act of limiting the supply of electricity to the grid during

conditions when it would normally be supplied. This is usually accomplished by locking or

feathering the turbine blades.

Cut-in speed:

The cut-in speed is the wind speed at which the generator is connected to the grid and

producing electricity. For some turbines, their blades will spin at full or partial RPMs below

cut-in speed when no electricity is being produced.

Feathering or Feathered:

Adjusting the angle of the rotor blade parallel to the wind, or turning the whole unit out of

the wind, to slow or stop blade rotation. Normally operating turbine blades are angled almost

perpendicular to the wind at all times.

Free-wheeling:

Free-wheeling occurs when the blades are allowed to rotate below the cut-in speed or even

when fully feathered and parallel to the wind. In contrast, blades can be “locked” and cannot

rotate, which is a mandatory situation when turbines are being accessed by operations

personnel.

Increasing cut-in speed:

The turbine’s computer system (referred to as the Supervisory Control and Data Acquisitions

or SCADA system) is programmed to a cut-in speed higher than the manufacturer’s set speed,

and turbines are programmed to be feathered at 90° until the increased cut-in speed is

reached over some average number of minutes (usually 5 – 10 min), thus triggering the

turbine blades to pitch back “into the wind” and begin to spin normally and produce power.

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Blade locking or feathering that renders blades motionless below the manufacturers cut in

speed, and don’t allow free rotation without the gearbox engaged, is more desirable for the

conservation of bats than allowing free rotation below the manufacturer’s cut in speed. This

is because bats can still collide with rotating blades even when no electricity is being

produced.

Acoustic deterrents:

Are a developing technology and will need further investigation closer to time of wind farm

operation, opportunities to test such devices may be available during operation of the facility.

Light lures:

Refers to the concept where strong lights are placed on the periphery (or only a few sides) of

the wind farm to lure insects and therefore bats away from the turbines. However, the long-

term effects on bat populations and local ecology of this method is unknown.

Habitat modification:

With the aim of augmenting bat habitat around the wind farm in an effort to lure bats away

from turbines, is not recommended. Such a method can be adversely intrusive on other fauna

and flora and the ecology of the areas being modified. Additionally, it is unknown whether

such a method may actually increase the bat numbers of the broader area, causing them to

move into the wind farm site due to resource pressure.

Currently the most effective method of mitigation, after correct turbine placement, is

alteration of blade speeds and cut-in speeds under environmental conditions favourable to

bats.

A basic "6 levels of mitigation" (by blade manipulation or curtailment), from light to

aggressive mitigation is structured as follows:

1. No curtailment (free-wheeling is unhindered below manufacturer’s cut in speed so all

momentum is retained, thus normal operation).

2. Partial feathering (45-degree angle) of blades below manufacturer’s cut-in speed in

order to allow the free-wheeling blades half the speed it would have had without

feathering (some momentum is retained below the cut in speed).

3. Ninety-degree feathering of blades below manufacturer’s cut-in speed so it is exactly

parallel to the wind direction as to minimize free-wheeling blade rotation as much as

possible without locking the blades.

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4. Ninety-degree feathering of blades below manufacturer’s cut-in speed, with partial

feathering (45-degree angle) between the manufacturer’s cut-in speed and mitigation

cut-in conditions.

5. Ninety-degree feathering of blades below mitigation cut in conditions.

6. Ninety-degree feathering throughout the entire night.

It is recommended that curtailment be applied from the start of operation at Level 3 on all

turbines for every night of the year from dusk until dawn.

The mitigations set out in Table 9 below is not required based on current results, since the

turbine layout was amended to avoid all High and Moderate bat sensitivities and their

buffers. However, should robust and scientifically defendable data gathered during the

operational study phase reveal higher bat mortalities than currently anticipated, and above

acceptable thresholds, the mitigations in Table 9 should be applied to the turbines identified

by the operational study as causing the highest impacts. Such curtailment specified in Table

9 will have to be at a maximum of Level 5.

The Table 9 below is based on the passive data collected. They infer mitigation be applied

(only when needed as described above) during the peak activity periods and times, and when

the advised wind speed and temperature ranges are prevailing simultaneously, considering

conditions in which 80% of bat activity occurred (normalised data). Bat activity at 80m height

were used, with wind speed and temperature data at 80m.

Table 9: The times and climatic conditions of implementation of mitigation measures (only when

needed, as described above), considering more than 80% bat activity, normalised data.

Terms of mitigation implementation

Peak activity (times to implement curtailment/ mitigation)

15 December – 31 December; sunset – 21:00

Environmental conditions in which to implement curtailment/ mitigation

Wind speed below 7.5m/s and simultaneously

Temperature above 20°C

Peak activity (times to implement curtailment/ mitigation)

1 – 30 April; sunset – 21:00

Environmental conditions in which to implement curtailment/ mitigation

Wind speed below 10m/s and simultaneously

Temperature above 19°C

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8 CONCLUSION

On the first site first visit, 11 July 2016, a SM2BAT+ detector was installed on one

meteorological mast. This monitoring system recorded bat activity every night for 12 months

from installation until it’s decommissioning on 3 July 2017. The long-term monitoring study

identifies bat species at risk of fatality to wind turbines, and patterns in their activity and

distributions (temporal and spatial).

Seven bat species were detected namely Eptesicus hottentotus, Miniopterus natalensis,

Neoromicia capensis, Tadarida aegyptiaca, Scotophilus dinganii, Pipistrellus hesperidus and

Myotis tricolor. Neoromicia capensis and Tadarida aegyptiaca were most commonly detected

by the monitoring system. Although both species have a conservation status of least concern,

these abundant species are of a large value to the local ecosystems as they provide a greater

contribution to most ecological services than the rarer species due to their higher numbers.

Bat activity is showing to be approximately three times higher at the monitoring height of

10m above the ground than 80m above the ground (Figure 16). This is most likely due to the

harsher wind and temperature conditions experienced at a greater elevation above the

ground and subsequently less insect prey in such conditions. T. aegyptiaca is the only species

recorded on site that shows higher activity at a monitoring height of 80m above ground level,

this is to be expected as it is an open-air forager and is also therefore more likely to be affected

by the rotor swept zone

The monitoring system detected the migratory species, Miniopterus natalensis, however it

has been detected with a relatively low activity index and mostly at the height of 10 m above

the ground. Myotis tricolor is also a seasonal migratory species which was detected by the

10m height bat detector in relatively low numbers over the months of February to May 2017.

These activity patterns do not indicate any significant migratory events.

A sensitivity map was drawn up indicating potential roosting and foraging areas. The High Bat

Sensitivity areas are expected to have elevated levels of bat activity and support greater bat

diversity. High Bat Sensitivity areas are ‘no – go’ areas due to expected elevated rates of bat

fatalities due to wind turbines. The original turbine layout had six turbines located within

moderate bat sensitivity areas and their buffers. Turbine positioning was amended and a new

and improved turbine layout was provided, where both Moderate and High sensitivity areas

and their buffers are avoided for turbine positioning. As such no turbines are proposed in any

bat sensitivities or their buffers and the proposed layout is acceptable.

It is recommended that curtailment be applied from the start of operation at Level 3

(described in Section 7) on all turbines for every night of the year from dusk until dawn.

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The mitigations set out in Table 9 (Section 7) is not required based on current results, since

the turbine layout was amended to avoid all High and Moderate bat sensitivities and their

buffers. However, should robust and scientifically defendable data gathered during the

operational study phase reveal higher bat mortalities than currently anticipated, the

mitigations in Table 9 should be applied to the turbines identified as causing the highest

impacts. Such curtailment specified in Table 9 will have to be at a maximum of Level 5 (Section

7).

If the recommended mitigation measures associated with impacts detailed in Section 5 are

applied and adhered to, the proposed Scarlet Ibis WEF is acceptable from a bat sensitivity

point of view.

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Werner Marais

Zoologist and Ecologist

MSc Biodiversity & Conservation

Pr.Sci.Nat. – SACNASP registration no. 400169/10

(Zoological Science)

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