LTREB: The Ecological and Organismal Basis for Early-Season Life History Variation in Tree Swallows Tachycineta Bicolor

该项目旨在扩展和升级对纽约州伊萨卡附近筑巢的树燕（Tachycineta bicolor）的生态学和生殖生物学的长期研究。这个种群的数量大约有300对。在过去的15年里，人们对树燕的种群进行了研究，并开发了大量的技术来有效地探索树燕的生物学和生态学。许多这些技术利用了树燕很容易在人工巢箱中筑巢的事实。像许多其他鸣禽一样，树燕的年存活率约为50%，因此一项为期五年的研究可以在许多鸟的整个繁殖期对它们进行采样。树燕是专性空中食虫动物。因此，它们对天气的短期变化异常敏感，因为它们的猎物飞虫在低温或下雨时无法飞行。以前的研究已经开发了每天采样和分析昆虫可用性的方法。在过去的十年里，伊萨卡岛研究的主要焦点之一是调查窝卵数量的季节性下降。较早产卵的雌性会产下更多的卵，而且它们不会为较早产卵付出可衡量的代价。北美各地的树燕已经提前了它们的产卵日期，显然是对全球气候变化的反应，因此了解产卵日期变化的决定因素和后果具有基础和应用的兴趣。目前的项目将试图回答三个相关的问题：1)昆虫数量和天气的变化如何影响单个燕子的产卵日期？2)飞行性能的变化是否与分娩日期和雏鸡供应性能的变化相关？3)短期内天气和食物供应的变化对有机体生物学和育种者适应性的影响是什么？飞行性能显然是空中食虫动物的关键特征，它将在一个已经建成的飞行性能测试隧道中进行评估，只需要进行轻微的修改。将通过一系列详细的行为观察，以及在专门开发的陷阱中收集的喂给小鸡的食物样本，来评估小鸡的供应表现。生理健康和压力将通过反复测量血液特征来评估。该项目将为一项长期研究带来新的详细测量水平，该研究已证明其在基础研究产出和各级学生教育方面的价值。通过研究燕子对温带生态系统中动态天气条件的反应，我们可以更好地了解动物的生物学与其环境之间的关系，无论是现在还是过去，并更好地预测环境变化将如何影响动物种群。

This project is to extend and upgrade a long-term study of the ecology and reproductive biology of tree swallows (Tachycineta bicolor) nesting near Ithaca, New York. This population numbers approximately 300 breeding pairs. The population has been studied for the past fifteen years, and a large number of techniques have been developed to efficiently explore tree swallow biology and ecology. Many of these techniques take advantage of the fact that tree swallows readily nest in artificial nest-boxes. Like many other songbirds, tree swallows have about a 50% annual survival rate, so a five year study can sample many birds during their entire reproductive lifetimes. Tree swallows are obligate aerial insectivores. Thus, they are unusually sensitive to short-term changes in weather, because their prey, flying insects, are unable to fly during cool temperatures or rain. Previous research has developed the methods for sampling and analyzing insect availability on a daily basis. One of the principal foci of the research in Ithaca in the past ten years has been investigating the seasonal decline of clutch size. Earlier laying females lay larger clutches, and they pay no measurable cost for laying earlier. Tree swallows across North America have advanced their date of laying, apparently in response to global climate change, and understanding the determinants and consequences of lay-date variation is thus of both basic and applied interest. The current project would attempt to answer three related questions: 1) How does variation in insect abundance and weather affect the lay-dates of individual swallows? 2) Does variation in flight performance correlate with variations in lay-date and chick-provisioning performance? 3) What are the consequences of short-term variation in weather and food supply both in terms of organismal biology and breeder fitness? Flight performance is clearly a critical trait for an aerial insectivore, and it will be evaluated in a Flight Performance Test Tunnel that is already constructed and in need of only slight modifications. Chick-provisioning performance will be assessed through a series of detailed behavioral observations coupled with samples of the food being delivered to the chicks collected in a specially developed trap. Physiological health and stress will be evaluated with repeated measurements of blood characteristics. This project would bring a new level of detailed measurements to a long-term study that has proved its worth both in basic research output and in education of students at all levels. By studying swallow reactions to the dynamic weather conditions of a temperate ecosystem, we can better understand the relationships between an animal's biology and its environment, both today and in the past, and make better predictions about how environmental changes will affect animal populations.