ABSTRACT: Inter-annual variations in the diets of seabirds are often a reflection of resource availability, with population dynamics and community structure implications. We investigated the trophic niche of Magellanic penguins Spheniscus magellanicus during the pre-molt stage in 6 years (2009 and 2013-2017) at Martillo Island, Beagle Channel, Argentina, using carbon and nitrogen stable isotope analysis of feathers. We found higher values in 2009 compared to the other years for both isotopes and estimated different proportions of prey in the diet of Magellanic penguins throughout the years. In 2009, penguins consumed mainly a mixture of benthic and benthopelagic fish, whereas from 2013 to 2017, the proportion of the pelagic form of squat lobster Munida gregaria, considered a key species in the Beagle Channel, increased over time and nearly dominated diets in 2017. Our results confirm that Magellanic penguins act as sentinels, reflecting shifts in the marine community of the Beagle Channel via inter-annual variation in their trophic niche and diet composition.

中文翻译：

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Beagle通道蜕皮前期麦哲伦企鹅Spheniscus magellanicus的营养位的年际变化

摘要：海鸟饮食的年际变化通常反映了资源的可获得性，具有种群动态和群落结构的影响。我们研究麦哲伦企鹅的生态位Spheniscus magellanicus期间使用羽毛的碳和氮的稳定同位素分析在Martillo岛，比格尔海峡，阿根廷，6年（2009年和2013 - 2017年）前蜕皮阶段。我们发现2009年的同位素值均高于其他年份，并且估计这些年来麦哲伦企鹅饮食中的猎物比例不同。在2009年，企鹅主要食用底栖鱼类和底栖鱼类的混合物，而从2013年至2017年，浮游形式的深蹲龙虾Munida gregaria所占比例，被认为是比格海峡中的关键物种，随着时间的流逝而增加，并在2017年几乎成为饮食的主要来源。我们的研究结果证实，麦哲伦企鹅充当哨兵，反映了比格海峡海洋群落通过其营养生态位和年际变化而发生的变化。饮食组成。