Foraging habitats of southern elephant seals, Mirounga leonina, from the Northern Antarctic Peninsula

ElephantIsland(EI)isuniquelyplacedtoprovidesouthernelephantseals(SES)breedingtherewith potentialaccesstoforaginggroundsintheWeddellSea,thefrontalzonesoftheSouthAtlanticOcean, the PatagonianshelfandtheWesternAntarcticPeninsula(WAP).Quantifyingwheresealsfrom EI foragethereforeprovidesinsightsintothetypesofimportanthabitatsavailable,andwhichareof particularimportancetoelephantseals.TwentynineSES(5sub-adultmales—SAM and24adult females—AF) wereequippedwithSMRUCTD-SLDRsduringthepost-breeding(PB2008,2009)and post-moulting(PM2007,2008,2009,2010)tripstosea.Therewerestrikingintra-annualandinter-sex differencesinforagingareas,withmostofthePBfemalesremainingwithin150kmofEI.OnePBAF travelleddowntheWAPasdid16outofthe20PMfemalesandforagednearthewinterice-edge.Most PM sub-adultmalesremainedclosetoEI,inareassimilartothoseusedbyadultfemalesseveralmonths earlier, althoughoneSAMspenttheearlypartofthewinterforagingonthePatagonianShelf.The watersoftheNorthernAntarcticPeninsula(NAP)containabundantresourcestosupportthemajority of theIslands’SESforthesummerandearlywinter,suchthattheanimalsfromthispopulationhave shortermigrationsthanthosefrommostotherpopulations.Sub-adultmalesandPBfemalesare certainlytakingadvantageoftheseresources.However,PMfemalesdidnotremainthereoverthe wintermonths,insteadtheyusedthesamewatersattheice-edgeinthesouthernWAPthatfemales from bothKingGeorgeIslandandSouthGeorgiaused.Femalesmademorebenthicdivesthansub- adultmales—again thiscontrastswithothersiteswhereSAMsdomorebenthicdiving.Unlikemost other populationsstudiedtodateEIisarelativelysoutherlybreedingcolonylocatedontheAntarctic continentalshelf.EIsealsareusingshelfhabitatsmorethanotherSESpopulationsbutsomeindividuals still employopenwaterforagingstrategies.Sea-icewasalsoveryinfluentialforPMfemaleswithmore foragingoccurringinheavierpack-ice.Largerfemalesusedareaswithheavierice-concentrationthan smallerfemales.Thestudydemonstratestheimportanceofshelfandslopehabitattoelephantseals, but alsohighlightedtheinfluenceofsea-iceandfine-scalebathymetryandlocaloceanconditionin determiningforaginghabitat.