UK Seabirds in 2008Results from the UK Seabird Monitoring Programme

This leaflet summarises the main findingsof the UK’s Seabird MonitoringProgramme (SMP) in 2008. Since 1986,the SMP has co-ordinated seabirdmonitoring on a UK-wide basis, using datacollected annually from a representativesample of colonies. In addition, threecensuses of breeding seabirds have beenconducted in Britain and Ireland during1969-70, 1985-88 and 1998-2002.Theprogramme is led by JNCC in partnershipwith the statutory country natureconservation agencies and otherconservation organisations (see back

cover for a full list of partners). The SMPenables its partners to monitor aspects ofthe health of the marine environment andto provide sound advice on theconservation needs of breeding seabirds.Recent developments in SMP datacollation and analytical techniques haveenabled us in this issue to present for thefirst time trends in population size of 19of the 25 species of seabird breeding inthe UK.We also present evidence derivedfrom these data that demonstrates howhuman activities have affected seabirdpopulations in the UK.

Welcome to the fourth edition of UK Seabirds

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Within the Seabird Monitoring Programmetwo aspects of state are measured:Breeding abundance - the number ofbreeding pairs or individuals is a mediumto long term measure of state (seabirds are long-lived species with relatively lowmortality rates and delayed onset ofbreeding).Breeding success - the number of chicksfledged per breeding pair more immediately

reflects fluctuations in environmentalconditions, such as food supply or weatherconditions.Breeding abundance and success are bothexpressed as population indices, wherebythe number of birds or number chicksfledged per pair in a sample of colonies in aparticular year is expressed as a percentageof the value for the same colonies in 1986,when the SMP was initiated.

Measuring the state of seabird populations in the UK

Why should we care about seabirds?

P Seabirds are an important component of biodiversity in the UK - over seven million breeding seabirds, of 25 species, benefit from the nutrient-rich waters of the NE Atlantic and from safe nesting sites along thousands of kilometres of coastline.

P Seabirds are a useful indicator of the state of our seas - seabirds are top predators: changes lower down the food chain and in the marine environment are likely to be manifested in their populations.

P Human activities affect seabirds in the UK - climate change, introductions of predators and commercial fishing have all had measurable adverse impacts on seabirds in the UK (see page 8). Humans have also benefited seabirds by providing them with food through waste disposal on land and at sea, and by providing safe nesting sites on top of buildings and on other man-made structures.

P Seabirds provide an important source of income for local economies -seabirds have a wide appeal to people: spectacular ‘seabird cities’ and engaging species like the Atlantic puffin draw visitors from near and far.

P The UK is an internationally important breeding area for seabirds - 13 species breeding in the UK are present in internationally significant numbers.

P Seabirds are protected by European law - under the EC Birds Directive, the UK’s most important seabird colonies are protected within Special Protection Areas (SPAs).Work is currently underway to identify areas at sea that are important for seabirds (e.g. for foraging) that could be designated under national and international legislation.

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UK’s seabirds - a status report

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Figure 1: Relative breeding abundance of seabird species in theUK between 1986 (the start of the SMP) and 2008.

In the UK, the number ofbreeding seabirds increasedfrom around 4.5 million in thelate 1960s to 7 million by theend of the 1990s. Since thelast census was conducted in1998-2002, the total numberof breeding seabirds hasprobably decreased: between2000 and 2008, changes inpopulation size of each of 19of the 25 species breeding inthe UK (Table 1) add up toan overall decrease ofaround 9%.Since the first seabirdcensus in the late 1960s,changes in breedingnumbers have varied greatlybetween individual species(see Table 1). Of the seabirdspecies breeding in the UK,only northern gannet andgreat skua have sustained anupward trend in populationsize from 1969 to 2008. Allother offshore surface-feeders (Figure 1c) havestarted to decline innumbers at various pointssince the mid-1990s andconsequently, there are now40% fewer black-leggedkittiwake and 16% fewergreat black-backed gullcompared with the late1960s (Table 1).Thepopulations of the threeoffshore diving speciesincreased in size throughoutthe 1970s, 80s and 1990s

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(Table 1) but started tolevel off in 2000 and arenow starting to decline(Figure 1e).In contrast to the ‘offshorespecies’, fewer inshorefeeders have shown positivetrends since the late 1960s(Table 1). Four inshorespecies have shown largedeclines. Herring gull androseate tern numbers haveboth declined by more than50% since 1969/70 (Table1), but while the latter hasstarted to slowly recoversince 2000 (Figure 1a),numbers of herring gullshave continued to decline(Figure 1b). European shagnumbers declined sharplyfollowing a year of partialnon-breeding in 1993 andstorms early in 1994.Thesubsequent recovery of shagnumbers was reversed byanother ‘storm-wreck’ inearly 2005 (Figure 1d).Thereare now 33% fewer shagsbreeding in the UK than in1969. Arctic skua numbershave declined sharply by twothirds since the early 1990s(Figure 1b). Numbers ofArctic skuas appear to beonly 14% lower than duringthe late 1960s (Table 1), butthe census in 1969/70probably underestimated thesize of the UK Arctic skuapopulation.

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Table 1: Changes in numbers of seabirds breeding in the UK during 1969-2008; 1986-2008 and2000-2008.The latest population estimates are in breeding pairs, apart from those of commonguillemot, black guillemot and razorbill, where individual adults present at the colony were counted.

Species

Latestpopulation

estimate(1998-2002)

Change inpopulation1969-2008

Change inpopulation1986-2008

Change inpopulation2000-2008

Inshore surface-feeders:Arctic skua 2,100 -14% -66% -57%(Mediterranean gull) 115 NA NA NAblack-headed gull 77,000 17% 11% 11%(mew gull) 21,000 NA NA NAherring gull 130,000 -69% -42% -33%Sandwich tern 12,000 -2% -29% -13%roseate tern #77 -92% -76% 38%common tern 10,000 -15% -16% -2%Arctic tern 47,000 -4% 28% 5%little tern 1,900 51% -4% 27%

Inshore divers:great cormorant 7,500 19% 9% -3%European shag 27,000 -33% -45% -25%(black guillemot) 39,000 NA 7% 4%

Offshore surface-feeders:northern fulmar 500,000 53% -14% -11%(Manx shearwater) 300,000 NA NA NA(European storm-petrel) 26,000 NA NA NA(Leach’s storm-petrel) 48,000 NA NA NAnorthern gannet *220,000 66% 30% 18%great skua 9,600 388% 164% 56%lesser black-backed gull 87,000 7% -17% -41%great black-backed gull 17,000 -16% -10% -6%black-legged kittiwake 380,000 -40% -52% -36%

Offshore divers:common guillemot 1,400,000 131% 28% -2%razorbill 190,000 50% 27% 5%Atlantic puffin 580,000 36% 40% -1%

U K S e a b i r d s i n 2 0 0 8 7

Species in parentheses were excluded from trend plots in Figure 1 as there were insufficient data.*Northern gannet figures are from the latest complete census in 2004/5. #Roseate tern estimate from2008. Population estimates have been rounded.

The percentage changes in population during the three periods were calculated by comparingestimates of population size in 2008 with census figures from 1969-70, 1985-88 and 1998-2002.Estimated population sizes for 2008 were obtained by extrapolating from 1998-2002 census figuresusing subsequent rates of change measured in the SMP sample of colonies.

Northern gannets. © Bob Perry

Seabirds in the UK areaffected by human activities.Some activities can benefitseabirds: for instance, fishingvessels can be an importantsource of food for thoseseabirds that feed ondiscarded fish and offal.However, the pressure fromsome activities can havesubstantial negative impactson seabirds in the UK.Table2 identifies these pressuresand assesses the nature andmagnitude of their impacts.The assessment was basedon expert judgement thatwas supported by publishedevidence where possible.The impacts of climatechange and of theintroduction of non-nativespecies were considered tobe the highest andincreasing (See pages 10-11and pages 14-15 for details).There is evidence that thepresence of commercialfishing for sandeels offeastern Scotland in the1990s negatively impactedon black-legged kittiwakepopulations.This pressurewas removed by a ban in2000. Details of this andother impacts of fishing aredetailed on pages 12-13.Large numbers of seabirdsfrom UK colonies havebeen killed by

contamination withhazardous substancesresulting from oil spills fromships during the last 20years. However, thismortality does not appearto have had any substantiallasting effect on the size ofthe UK breedingpopulations of those speciesaffected (mainly commonguillemot and razorbill).Activities associated withthe development ofoffshore renewable energysources and with leisureand recreation can createvisual disturbance toseabirds that effectivelyleads to the loss of habitatavailable for foraging, nest

building and other essentialactivities.These impacts arecurrently localised andconsidered to be low acrossthe UK as a whole.However, as UK anddevolved governmentsstrive to meet their targetsfor renewable energyproduction, the level ofvisual disturbance andhabitat loss from theresulting offshoreinstallations is likely toincrease. It is unclear if thisincreased pressure willresult in fewer birds usingUK waters or whether theywill relocate elsewherearound the UK. Marine litteris ingested by northern

Seabirds under pressure

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Burning of fossil fuels is a major source of green house gas.© Peter Wakely/Natural England

Climate change Multiple Reduction in abundance and quality High/increasingof seabird prey (i.e. lesser sandeels)

Contamination Oil & gas; Mortality following contamination with Low/stochastic by hazardous shipping spilled hazardous substancessubstances operations

Marine litter Multiple Plastic waste at sea is ingested by Low/no change surface feeding seabirds

Visual disturbance Renewable Offshore windfarms and watersports Low/increasing & habitat loss energy; leisure can exclude seabirds from foraging areas

& recreation

Introduction of Shipping Size reduction or extinction of seabird High/increasingnon-native species operations; colonies as a result of predation by

leisure & non-indigenous mammalsrecreation

Removal of species Fishing Mortality from bycatch (i.e. incidental Unknown/ unknown (target & non-target) killing of birds in fishing gear)

Reduction in discards and offal Unknown /increasing discharge lowers food availability for scavenging species

Reduction in abundance of lesser High/sandeels available to seabirds in the decreased to low North Sea

Activitycausingpressure ImpactPressure

Magnitude /trend ofimpact

Table 2: Pressures affecting seabirds in the UK (for further explanation see pages 10-11, 12-13 and 14-15.)

fulmars and other surfacefeeding seabirds.As a consequence, nondegradable plasticsaccumulate in large

quantities in their stomachs.However it is unclear whateffect this ingested litter hason the birds’ health andlong-term survival.

Continued monitoring ofspecies at risk will providean early warning of negativeimpacts of all the pressuresdescribed above.

U K S e a b i r d s i n 2 0 0 8 9

Sea-surface temperatures in the north eastAtlantic and UK coastal waters have beenrising since the 1980s by around 0.2-0.9˚Cper decade, with the most rapid risesoccurring in the southern North Sea andthe English Channel1 (Figure 2).The risingsea temperatures led to a change in theNorth Sea plankton community in the late1980s and consequently large reductions inabundance of the zooplankton on whichlarval fish feed2. In addition, poor sandeelproductivity is associated with warmer sea-surface temperatures3. Analyses of datacollected by the SMP have providedevidence strongly suggesting climate drivenchanges in the food chain have had acutenegative impacts on seabirds breeding onBritain’s North Sea coast. Low breedingsuccess of kittiwakes and of other speciessuch as common guillemot that rely onsandeels, have occurred with increasing

frequency in recent years (Figure 3). Indeed,kittiwakes in eastern Britain have fledgedfewer young in recent, warmer years4,5 (seeFigure 4), which is thought to be linked tothe relationship between temperature andsandeel productivity (see above).Observations at colonies monitored by theSMP confirmed that seabirds were catchingfewer and smaller sandeels than normalduring years of poor breeding performance.The calorific content of these sandeels wasalso much lower in 2004, one of the leastsuccessful breeding seasons for seabirds inrecent times6.

Long-term declines in numbers of black-legged kittiwake are expected to continueunless the recent rises in sea-surfacetemperature are reversed4. Reversing therecent warming of the oceans is reliant onthe success of global efforts to combat

Figure 2: 25-year trend in sea-surface temperature (°C/decade, 1982-2006) for the north east Atlantic.Reproduced with permission from Holliday et al. 20081.

Climate change impacts – the evidence so far

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Figure 4: The relationship between mean annual breeding success of black-legged kittiwake andmean winter sea-surface temperature (lagged one year earlier). Reproduced with permission fromFrederiksen et al. (2007)5.

Figure 3: Mean annual breeding success of black-legged kittiwake and common guillemot in the UK,1986-2008.

climate change. In the short-term a betterunderstanding of the interactions betweenclimate, plankton and fish may help to

mitigate the impacts of climate change byidentifying where other pressures can bemost effectively reduced or eliminated.

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For years, some seabirds have benefitedfrom fisheries through food provided at seaby discharging offal and discarding undersizefish. As a result, the abundance of scavengingspecies (e.g. great skua, northern fulmar)may have been elevated above levels thatnaturally occurring food sources couldsustain. The necessary introduction ofmeasures to conserve fish stocks hasconsequently reduced the amount ofdiscards, as has the decline of somecommercial fisheries, which has also resultedin less offal being discharged. It isconceivable that the reduction in foodprovided by the fishing industry may havecontributed to a population downturn offulmars and other offshore surface-feederssince the mid-1990s (see Figure 1c).

Another consequence of fewer discards isthat great skuas have had to relyincreasingly on other food sources, includingthe predation of other seabirds, which ishaving a negative impact on their preypopulations (e.g. Arctic skuas)7.

But fisheries can compete with seabirds forthe fish they eat. Off southeast Scotland asandeel fishery that operated in the 1990ssignificantly depressed adult survival andbreeding success of black-legged kittiwakesat adjacent colonies compared with yearsprior to the fishery opening and after it wasclosed8. Since 2000 there has been a banon sandeel fishing off eastern Scotland andNE England. If fishing is resumed to levelsthat significantly reduce local sandeel stock

Do fisheries affect seabirds?

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Costs and benefits of fishing: a northern fulmarcaught on a hook set on a commercial long-line(top); fulmars flocking around a commercial long-lining vessel to scavenge discarded fish (bottom)(Terje Lislevand/RSPB)

size, it would probably exacerbatereductions in breeding success andsurvival caused by increases in sea surfacetemperature as a result of climate change4,5,8(see pages 10-11).

Northern fulmars appear to beparticularly susceptible to entanglement inoffshore fishing nets and regularly take thebaited hooks of long-line fisheries. Aukscan become trapped in inshore salmonnets. However, data are currently lackingon the numbers of seabirds caught bylong-line and other fisheries in UK waters.Such information would contribute toefforts at a European level to address theimpact of seabird bycatch.

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Introductions of non-native mammals toislands have had major negative impactson the resident colonies of ground-nesting seabirds. Mammals such asbrown rat and American mink predateon seabird eggs, chicks and in somecases, adult birds. Predation by mammalshas caused the extinction of somecolonies of ground-nesting seabirds suchas terns, gulls, storm-petrels, Manxshearwater and Atlantic puffin. Othercolonies have been substantiallydepleted, with seabirds confined tobreeding in places that are inaccessibleto predators. For example, Figure 5shows that significantly more Atlanticpuffins breed on predator-free islandsthan on those with mammalianpredators.

Common tern chicks from the cache of anAmerican mink on an island in Argyll & Bute(J.C.A. Craik)

The pressure from non-native mammalscan be eliminated through management: a)Eradication of non-native mammals fromislands has resulted in the expansion ofexisting seabird colonies and in the re-colonisation by seabird species. b)Quarantine measures can prevent theinvasions of islands by non-native mammals.Some highly effective interventions havebeen made but a more strategic nationalapproach would achieve the greatestconservation gains for seabirds for the leastcost. Figure 5 demonstrates how SMP dataon colony size could be used to prioritisecolonies for management.

Island invaders

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Figure 5: The impact of the presence of mammalian predators on the size of Atlantic puffin colonieson islands in the UK. (Source Mitchell & Ratcliffe 2007)9.The vertical distance between the black datapoints and the red line indicates the potential loss in numbers following invasion; the vertical distancebetween the red data points and the black line indicate the potential gain in numbers once predatorshave been eradicated.These data can therefore be used to identify those colonies where a) theremoval of predators would result in the greatest gains in seabird numbers (e.g. A); and b) inadequatequarantine measures may lead to predator invasion that would result in the greatest reductions inseabird numbers (e.g. B) .

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Front page photograph: Black-legged kittiwake. ©Hugh Harrop / www.hughharrop.comThe Joint Nature Conservation Committee advises the UK Government on national and international wildlifeand conservation issues on behalf of Natural England, the Countryside Council for Wales, Scottish NaturalHeritage and the Northern Ireland Environment Agency

ISBN-13: 978 1 86107 611 3 ©JNCC 2009

Acknowledgements

The Seabird Monitoring Programme (SMP) relieson the generous help of many surveyors – oftenvolunteers - to supply information.The followingorganisations work on the SMP in partnershipwith JNCC:Scottish Natural Heritage, Countryside Councilfor Wales, Natural England, Northern IrelandEnvironment Agency, Royal Society for theProtection of Birds, Centre for Ecology andHydrology,The Seabird Group, Shetland OilTerminal Environmental Advisory Group,BirdWatch Ireland, British Trust for Ornithology,The National Trust for Scotland, National Parksand Wildlife Service (Dept. of Environment,Heritage and Local Government – Republic of Ireland).

The new SMP website is now online!Visit www.jncc.gov.uk/smp to enter andview counts for any seabird colony inBritain and Ireland.

A range of breeding seabird datasets are also now available atwww.jncc.gov.uk/page-4460

For more information about the SMP andmonitoring seabirds in the UK, go towww.jncc.gov.uk/seabirds or contact:Dr Matthew Parsons, SMP Co-ordinator.Tel: 01224 655715, email:matt.parsons@jncc.gov.uk or write to:JNCC, Dunnet House, 7 Thistle Place,Aberdeen AB10 1UZ

1 Holliday, N.P., Kennedy, J., Kent, E.C., Marsh, R., Hughes, S.L., Sherwin,T. & Berry, D.I. 2008. MCCIP Annual Report Card2007-2008 Scientific Review - Sea Temperature. Marine Climate Change Impacts Partnership www.mccip.org.uk/arc.2 Beaugrand, G., Brander, K. M., Lindley, A., Souissi, S. & Reid, P. C. 2003. Plankton effect on cod recruitment in the NorthSea. Nature 426: 661-664.3 Arnott, S. A. & Ruxton, G. D. 2002. Sandeel recruitment in the North Sea: demographic, climatic and trophic effects. Mar.Ecol. Prog. Ser. 238: 199-210.4 Frederiksen, M., Harris, M. P., Daunt, F., Rothery, P. and Wanless, S. (2004) The role of industrial fisheries and oceanographicchange in the decline of North Sea black-legged kittiwakes. Journal of Applied Ecology, 41, 1129-1139.5 Frederiksen, M., Edwards, M., Mavor, R. A., and Wanless, S. 2007. Regional and annual variation in black-legged kittiwakebreeding productivity is related to sea surface temperature. Mar. Ecol. Prog. Ser.350: 137–143.6 Wanless, S., Harris, M. P., Redman, P. & Speakman, J. R. 2005. Low energy values of fish as a probable cause of a majorseabird breeding failure in the North Sea. Mar. Ecol. Prog. Ser. 294: 1-8.7 Votier, S. C., Furness, R.W., Bearhop, S., Crane, J. E., Caldow, R.W. G., Catry, P., Ensor, K., Hamer, K. C., Hudson, A.V.,Kalmbach, E., Klomp, N. I., Pfeiffer, S., Phillips, R. A., Prieto, I. & Thompson, D. R. 2004. Changes in fisheries discard rates andseabird communities. Nature 427: 727-730.8 Frederiksen, M., Jenson, H., Daunt, F., Mavor, R. and Wanless, S. 2008. Differential effects of a local industrial sand lancefishery on seabird breeding performance. Ecological Applications, 18(3): 701–710.9 Mitchell, P.I. & Ratcliffe, N. 2007. Abundance & distribution of seabirds on UK islands – the impact of invasive mammals. InProceedings of the conference on Tackling the problem of invasive alien mammals on seabird colonies – Strategicapproaches and practical experience. Edinburgh 2007.The National Trust for Scotland, Royal Zoological Society of Scotlandand Central Science Laboratory.

www.jncc.gov.uk/seabirds

References