Southern Bird | |
Foraging ecology and dive behaviour of Pitt Island shags (Stictocarbo featherstoni) | Notornis and Birds New Zealand | |
Bell, M1  | |
关键词: dive depth; dive duration; foraging ecology; Pitt Island shag; Stictocarbo featherstoni; | |
DOI : | |
学科分类:农业科学(综合) | |
来源: Ornithological Society of New Zealand Inc. | |
【 摘 要 】
TheforagingecologyofPittIslandshag(Stictocarbofeatherstoni)wasstudiedusingGPSarchivalandTimeDepthRecorderdevicesdeployedonincubatingbirds.PittIslandshagsforagedexclusivelyduringdaylight,withatendencyformalestoforagemainlyduringmid-morningandlateafternoon,andfemalesintheearlymorningandaroundmid-day.Meanforagingdistancefromcolonieswas5.2km(range0.4-18.2km),withmales(mean9.7km)foragingsignificantlyfurtherthanfemales(3.7km).Bothsexesshowedhighforagingsitefidelity.Thedepthofmost(83%)divesgt;5mdeepweresimilartothedepthoftheprecedingdive(within30%),indicatingthatbirdsarealmostexclusivelybenthicfeedingwiththesmallfluctuationsindivedepthlikelyreflectingchangesinseafloortopography.Meandivedepthwas6.6m,withmaximumdepth24.4m,although90%ofalldiveswereshallowerthan13mdeep.Meandivedurationwas22s,withamaximumof69s,althoughover90%ofdiveswereshorterthan40s.Therewasapositiverelationshipbetweendivedurationanddivedepth,wheredeeperdiveshadlongerduration.Meanrestperiodwas19swithaweakpositiverelationshipbetweenrestperiodanddurationoftheprecedingdive.Meanpercentagetimeunderwaterduringeachforagingtripwas50.1%,indicatingrelativelyhighforagingefficiency.Favouredforaginglocationsinshallowinshorewatersislikelytobearesponsebybirdsselectivelyforaginginshelteredwatersprotectedfromoceanicswells.Thismaybeafactorinfluencingpopulationdeclinesasitintensifiesrisktobirdsaspotentialthreatsmaybemoreconcentratedintheseareas.
【 授权许可】
Unknown
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Files | Size | Format | View |
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RO201912090835283ZK.pdf | 1512KB | download |