Refining isotopic tools to trace avian migratory origins and nutrient allocation strategies

对候鸟和其他动物的有效研究和养护要求在年度周期的所有阶段之间建立迁徙联系。由于跟踪个体运动的困难，这项任务变得复杂，特别是小型生物体的运动。自然出现的几种元素的稳定同位素显示了不同景观和大洲的空间格局(等值线)，这使移徙研究发生了革命性的变化，因为这种方法不需要对个体进行初始标记，而是依赖于测量内源同位素指纹来确定个体的来源。这种方法是基于这样一个事实，即环境中自然产生的稳定同位素比率以可预测的方式输送到更高级别的消费者手中。这项建议旨在通过确定导致羽毛角蛋白种内和种间同位素模式的关键因素，提高我们对个体分配等角蛋白的能力，特别是基于降水中存在的同位素特征(即2H/1H，18O/16O)的那些。这将由博士生项目完成，主要是通过仔细测量圈养鸟类的饮食、饮用水、羽毛和爪子，以及对已知来源的野生鸟类进行广泛的分析。这项工作的第二部分将重点放在使用相同的同位素指纹方法(但这次是13C/12C和15N/14N)来追踪营养物质进入鸡蛋的途径。这将允许对蛋白质和脂类对生殖的内源和外源贡献进行定量建模。这种方法将允许直接测试候鸟在将“资本”输送到它们的繁殖地或依靠当地环境(即“收入”)促进繁殖所使用的策略。最后，在该提案的最后两年，将由一名博士后研究员完成一个基于田间的计划，以追踪北极高地繁殖的鹅对其蛋的营养分配。总之，这些项目将使我们能够预测和模拟鸟类系统中同位素变化的来源，从而推动整个同位素生态学领域的发展。

Effective study and conservation of migratory birds and other animals requires that migratory connections be made between all phases of the annual cycle. This task is complicated by the difficulties in tracking individual movements, especially of small bodied organisms. The use of naturally occurring stable isotopes of several elements that show spatial patterns across landscapes and continents (isoscapes) has revolutionized studies of migration since the approach does not require initial marking of individuals but relies instead on the measurement of endogenous isotopic fingerprints to assign individuals to origin. This approach is based on the fact that naturally occurring stable isotope ratios in the environment are transported in a predictable fashion to higher-order consumers. This proposal aims at improving our ability to assign individuals to isoscapes, especially those based on isotopic signatures present in precipitation (i.e. 2H/1H, 18O/16O) by determining key factors that contribute to within- and between-species isotopic patterns in feather keratins. This will be accomplished by Ph.D. student projects largely through the careful measurement of diet, drinking water, feathers and claws of captively raised birds and through the widespread assay of wild birds from known origins. A second component of the work will focus on using the same isotopic fingerprinting approach (but this time with 13C/12C and 15N/14N) to trace pathways of nutrients to eggs. This will allow the quantitative modeling of both endogenous and exogenous contributions of proteins and lipids to reproduction. Such an approach will allow the direct testing of the strategies migratory birds use in either transporting "capital" to their breeding sites or relying on local environments (i.e. "income") to fuel reproduction. Finally, a field-based program to trace nutrient allocations by high Arctic breeding geese to their eggs will be accomplished by a postdoctoral fellow during the last two years of the proposal. Together, these projects will move the whole field of isotopic ecology forward by allowing us to anticipate and model sources of isotopic variation in avian systems.