Stable isotopes indicate sex-specific and long-term individual foraging specialisation in diving seabirds
Stable isotopes indicate sex-specific and long-term individual foraging specialisation in diving seabirds
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DOI：
10.3354/meps311157
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发表时间：
2006-01-01
影响因子：
2.5
通讯作者：
Croxall, John P.
中科院分区：
文献类型：
--
作者：
Bearhop, Stuart;Phillips, Richard A.;Croxall, John P.
觅食生态学的一个重要方面是种群中不同个体或性别以不同方式利用食物资源的程度。对于潜水海鸟来说，这些信息大多与短期饮食数据或时间预算等间接措施有关。此外，由于与传统采样技术相关的偏差，饮食专业化可能难以检测。我们使用血液和羽毛中的稳定同位素比率来推断4种潜水海鸟类群之间的营养和栖息地专业化-巴布亚企鹅Pygoscelis papua，通心粉企鹅Eudyptes chrysolophus，南乔治亚州沙格Phalacrocorax（atriceps）georgianus和Kerguelen沙格P.（atriceps）verrucosus。这使我们能够调查觅食专业化和评估是否社会优势或觅食偏好的差异解释了观察到的模式。在所有的类群中，性别是已知的，我们发现，男性觅食在较高的营养水平（三角洲N-15值）比女性，虽然这是不显着的通心粉企鹅。我们认为这与雌性通心粉企鹅的双重觅食策略有关。对于南乔治亚州的沙格，我们发现，与性别有关的饮食差异持续了很长一段时间（从羽毛和血液的稳定同位素分析推断）。我们认为，营养的差异是由生理表现的差异，男性往往比女性更深，因为他们更大的尺寸潜水，因此能够获得更高的营养级猎物项目。此外，男性和女性的shags往往在一天中的不同时间觅食;因此，男性的社会优势不太可能推动观察到的差异。我们还记录了在血液中的稳定同位素签名（代表繁殖季节饮食）和羽毛（主要代表以前的非繁殖季节饮食）在南乔治亚州和Kerguelen shags之间的高度显着的关系。这强烈表明，这2个类群包括个人与不同的觅食专业化（和最有可能觅食的位置），保持了很长一段时间。
An important aspect of foraging ecology is the extent to which different individuals or genders within a population exploit food resources in a different manner. For diving seabirds, much of this information relates either to short-term dietary data or indirect measures such as time budgets. Moreover, dietary specialisation can be difficult to detect due to biases associated with conventional sampling techniques. We used stable isotope ratios in blood and feathers to infer trophic and habitat specialisations among 4 diving seabird taxa - the gentoo penguin Pygoscelis papua, the macaroni penguin Eudyptes chrysolophus, the South Georgian shag Phalacrocorax (atriceps) georgianus and the Kerguelen shag P. (atriceps) verrucosus. This allowed us to investigate foraging specialisation and assess whether social dominance or differences in foraging preferences explained the observed patterns. In all taxa where sexes were known we found that males foraged at a higher trophic level (delta N-15 values) than females, although this was not significant in macaroni penguins. We believe that this is linked to a dual foraging strategy among female macaroni penguins. For South Georgian shags, we found that sex-related dietary differences persisted for long periods (inferred from stable isotope analyses of feathers and blood). We suggest that the trophic differences are driven by differences in physiological performance, with males tending to dive deeper than females because of their larger size, and hence able to access higher trophic level prey items. Moreover, male and female shags tend to forage at different times of day; therefore, social dominance by males is unlikely to be driving the observed differences. We also recorded highly significant relationships between stable isotope signatures in blood (representing the breeding season diet) and those in feathers (mostly representing the previous non-breeding season diet) in both the South Georgian and Kerguelen shags. This strongly suggests that these 2 taxa include individuals with distinct foraging specialisation (and most probably foraging locations) that are maintained over long periods.