Structural size measurements and isotopic signatures of foraging among adult male and female Adélie penguins (Pygoscelis adeliae) nesting along the Palmer Archipelago near Palmer Station, 2007-2009

Sexual segregation in vertebrate foraging niche is often associated with sexual size dimorphism (SSD), i.e., ecological sexual dimorphism. We examined ecological sexual dimorphism among sympatric nesting Pygoscelis penguins near Palmer Station, Antarctica, asking whether environmental variability in the form of winter sea ice is associated with differences in male and female pre-breeding foraging niche. Each season, study nests, where pairs of adults were present, were individually marked and chosen before the onset of egg-laying, and consistently monitored. When study nests were found at the one-egg stage, both adults were captured to obtain blood samples used for molecular sexing and stable isotope analyses, and measurements of structural size and body mass. At the time of capture, each adult penguin was quickly blood sampled (~1 ml) from the brachial vein. After handling, individuals at study nests were further monitored to ensure the pair reached clutch completion, i.e., two eggs. Molecular analyses were conducted at Simon Fraser University following standard PCR protocols, and stable isotope analyses were conducted at the Stable Isotope Facility at the University of California, Davis using an elemental analyzer interfaced with an isotope ratio mass spectrometer

脊椎动物觅食生态位的性别分离通常与性大小二态性（Sexual Size Dimorphism, SSD）相关，即生态性别二态性。本研究针对南极洲帕尔默站附近同域筑巢的Pygoscelis企鹅开展生态性别二态性分析，探究以冬季海冰为表现形式的环境波动是否与雌雄个体繁殖前的觅食生态位差异相关。每个繁殖季，研究人员均在产卵开始前选定有成鸟对栖息的研究巢，并对其进行个体标记与持续监测。当研究巢处于产1枚卵阶段时，捕获两只成鸟以采集血液样本，用于分子性别鉴定、稳定同位素分析，同时测量其躯体尺寸与体质量。捕获时，研究人员快速从每只成鸟的臂静脉采集约1毫升血液样本。完成操作后，继续监测研究巢中的个体，确保该繁殖对完成产卵（即产下2枚卵）。分子分析在西蒙弗雷泽大学依照标准聚合酶链式反应（PCR）流程开展；稳定同位素分析则在加州大学戴维斯分校稳定同位素实验室完成，采用与同位素比率质谱仪联用的元素分析仪进行检测。