AlongtermincreaseineggshellthicknessofGreenlandicP

Along-termincreaseineggshellthicknessofGreenlandicPeregrineFalconsFalcoperegrinustundriusKnudFalka,SbrenMbllerb,T,WilliamG.MattoxcaTeglstrupvej6a,DK-2100Copenhagen,DenmarkbRoskildeUniversityLibrary,P.O.Box258,DK-4000Roskilde,DenmarkcConservationResearchFoundation,8300GantzAve.,Boise,ID83709,USAReceived11October2004;accepted18February2005Availableonline10May2005AbstractThicknessofeggshellfragmentsandwholeeggsfromthePeregrineFalconFalcoperegrinuscollectedinSouthandWestGreenlandbetween1972and2003wasmeasuredandcomparedtoshellthicknessofpre-DDTeggs,alsocollectedinGreenland.Linearregressionyieldsasignificantincreaseintheaveragethicknessofeggshellsovertheperiodof0.19%peryear,correspondingtoachangeineggshellthinningfrom13.9%in1972to7.8%in2003.Backwardsextrapolationofthedata,suggeststhattheGreenlandicPeregrinepopulationprobablywasnevercriticallyaffectedbyDDT-inducedeggshellthinning.Bysamplingeggshellfragmentsinmanyneststhespatialandtemporalsampledistributionwasenlarged,allowingthedetectionofasignificantlong-termdecreaseinpollutant-inducedeggshellthinning—atrendthatcouldnothavebeenidentifiedifonlytherarerwhole,addledeggshadbeensampled.D2005ElsevierB.V.Allrightsreserved.Keywords:PeregrineFalcon;Falcoperegrinus;Eggshellthickness;Greenland;Arctic1.IntroductionTheeffectsofpersistentorganicpollutants(POP)ontheeggshellthicknessandbreedingsuccessinhigh-trophiclevelbirdshavebeenwidelydocu-mented.EspeciallyDDTanditsderivativeshavebeenidentifiedasakeygroupofPOPsresponsibleforthewidespreadreductioninbreedingsuccessandsubsequentpopulationdeclineinthePeregrineFalconFalcoperegrinus(Hickey,1969;HickeyandAnderson,1968;Newton,1979;Peakalletal.,1975,1976;PeakallandKiff,1979;PeakallandLincer,1996;Ratcliffe,1970,1993;WalkerIIetal.,1973).TheGreenlandPeregrineFalcon(F.p.tundrius)populationhasbeenthesubjectoflong-termstudiesinWestGreenlandsince1972(e.g.Burnhamand0048-9697/$-seefrontmatterD2005ElsevierB.V.Allrightsreserved.doi:10.1016/j.scitotenv.2005.02.024TCorrespondingauthor.Tel.:[phone];fax:[phone].E-mailaddresses:[e-mail](K.Falk)[e-mail](S.Mbller),[e-mail](W.G.Mattox).ScienceoftheTotalEnvironment355(2006)127–134)andSouthGreenlandsince1981(Falketal.,1986;FalkandMbller,1988).TheGreenlandpopulationwasconservativelyestimatedat500–1000pairs(FalkandMøller,1988).AutumnmigrationcountsintheeasternUS,wherePeregrinesfromGreenlandandtheeasternCanadamixduringthemigration,suggestaslightincreaseinArcticpop-ulations(TitusandFuller,1990).ItisthustobeexpectedthatapopulationofArcticPeregrinespossiblyrecoveringfromtheeffectsofPOP-exposurewillshowanincreaseineggshellthicknessovertime.Eggshellthicknessanalyseshaveoftenreliedonmeasurementsofwholedeadeggs,which,however,i)arerelativelyrareoccurrences,ii)arenotpresentinthemostsuccessfulnests(alleggshatch),andiii)maypotentiallybebiasedsinceverythineggsmightbreak(Odsjo¨,1982).Byusingeggshellfragmentsfromallnests,amorerepresentativeandcomprehensivesurveyofthewildpopulationcanbeobtained.Basedontheintra-andinter-clutchvariationinshellthickness,FalkandMbller(1990)recommendedthatstudiesofeggshellthinningshouldincludefragmentsfromasmanynestsaspossible.AlthoughstudiesofArcticPeregrineFalconpopulationshaveshownthatthinninginrecenteggsislessseverethanoldersamples(Ambroseetal.,2000;Johnstoneetal.,1996),nogradualtimetrendshavebeendocumented,probablyduetorelativelyshortdurationofmostfieldstudies.Thispaperpresentstheresultsofa32-yearstudyofchangesineggshellthicknessinGreenlandicPeregrines,inordertotesttheassumptionthatshell-thinningiscontinu-ouslyimprovingfollowingthegeneralreductioninuseofthecontaminantscausingtheeffect.2.Materialsandmethods2.1.StudyareaandsamplingThestudycombinessamplesfromtwostudyareas(Fig.1):SouthGreenland(samplesfrom1981–2003),andWestGreenland(samplesfrom1972–1988).TheSouthGreenlandstudyareacoverstheinnerpartsofthethreesouthernmostmunicipalitiesofSouthwestGreenland,Nanortalik,QaqortoqandNarsaq,approx.within608–618Nand458–468W.TheareaislowArctic,withtundravegetation,andwillowandbirchshrubinthewarm,sub-arcticareasfarfromthecooloutercoast.Asubstantialpartoftheareaisgrazedbysheep.FieldsurveysofthePeregrineFalconpopulationhavebeenconductedhereannuallybetween1981and2003byKFandSM.TheWestGreenlandstudyareacoversthelow-arcticinlandareasaroundKangerlussuaq(SbndreStrbmfjord),approx.within66845V–67815VNand508–528W.Theareaishilly/mountainousanddottedwithlakes,andisdividedbythelargefjordSbndreStrbmfjord.Themainvegetationistreelesstundra(BurnhamandMattox,1984).Studieswereinitiatedin1972byWGMandRichardGraham(seeBurnhamandMattox,1984),andthepresentpaperincludeseggshellfragmentsfrom1972–1988.Inbothsurveyareas,activenestswerevisitedatleastoncepost-hatching,and,whenconditionsallowed,thenestscrapecarefullysearchedforegg-shellfragmentsderivingfromthehatchedeggs.Inaddition,anywholedeadeggspresentwerecollectedforcontaminantanalyses;wholeeggsareincludedinthispaperforcomparisonwithfragments,whilecontaminants