Female-Biased Sex Ratio in Moulting Black-Necked Grebes Podiceps nigricollis in Southern Spain
[摘要] WetestedifBlack-neckedGrebe,aspeciesinwhichbothsexesundertakemoult-migration,haveanunbiasedsexratioatamoultingsiteinEurope,aspreviouslyfoundinNorthAmericaandaswasexpectedforaspecieswithbiparentalcare.Forthisweusedauniquelong-termdatasetof5821grebescapturedforringingthroughoutthemoultingseasonsof2006–2012intheOdielsalt-marshes(SWSpain).Thegrebesweresexedandclassifiedasadults(74%)orjuveniles(26%).BirdsringedatOdielwererecoveredoverawideareauptocentralRussiaandsouthtotheCanaryIslandsandMorocco.Wereportonauniquecaseofastronglybiasedsexratioinamoult-migratingbirdspecieswithbiparentalcare,inwhichadultfemalesweresignificantlymoreabundantthanadultmalesinall7years(1.6–4.2femalespermale).Biasedsexratioswerenotfoundamongjuveniles.DifferencesbetweenNorthAmericaandEuropeinthesexratiosofadultBlack-neckedGrebesatmoultingsitesmaybeexplainedbythemuchlargerAmericanmoultingsites,whichwouldfacilitateanunbiasedsexratioinNorthAmerica,butnotinEurope.MoultingsitesinEuropemayreachcarryingcapacitybecauseoftheirsmallersize,forcingthelatemigratingindividuals(adultfemalesandjuveniles)tomovelongerdistancestositesfartherfrombreedingareas,suchustheOdielsalt-marshes.
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[效力级别] [学科分类] 动物科学
[关键词] Waterbirds [时效性]
