DISSERTATION RESEARCH: Survival and performance costs of phenotypic responses to predation risk

这项研究调查了幼雏鸣禽的生长速度是否更快，离开巢穴的风险是否更高，离开巢穴后的存活率是否更低。捕食是野生动物死亡的一个主要原因。当被捕食的风险是可变的，被捕食的物种预计会表现出灵活的发育反应，以减少它们被捕食者杀死的风险。例如，当巢被捕食的风险很高时，雏鸟可能会生长得更快，更早离开巢。然而，生命早期灵活的发育反应可能在生理上代价高昂，并增加生命后期的死亡率。通过模拟增加的捕食，研究人员将实验确定不同的巢穴捕食对黑眼Juncos雏鸟生长速度和羽化时间的影响。每只鸟都将被贴上无线电发射器的标签，以确定它们离开巢穴后的命运。这项研究还将探讨雏鸟的活动水平和行为是否会降低死亡风险，并补偿生理成本。研究结果将对控制野生动物种群增长和下降的关键因素提供重要见解，并导致对这些种群的更有效管理。此外，该项目将包括指导本科生和研究生，并将为高中生编写教育材料。还将为当地科学教育中心制作学龄儿童教育视频。该项目验证了一种假设，即黑眼Juncos的快速生长是对巢穴捕食风险的反应，损害了它们的流动性，并导致它们在生命的老年阶段死亡风险增加。研究人员将使用扬声器播放典型的巢穴捕食者的声音，以提高父母和后代对巢穴捕食风险的感知，并检查雏鸟出生后的死亡率。初步数据显示，在“高风险”巢穴中的雏鸟离开巢穴时翅膀较短，飞行能力较差，但目前尚不清楚这些雏鸟离开巢穴后是否会更频繁地被捕食。就在雏鸟离开巢穴之前，研究人员将安装无线电发射器以帮助跟踪。将收集雏鸟离开巢穴后每天活动的频率和距离的数据；它们是否更常躲在茂密的植被中，在那里鹰等捕食者更难以接近它们；以及他们是否真的更容易死亡。结果将促进我们对生长可塑性对后代后期死亡率的传递效应的理解。

This study investigates whether young songbirds that grow faster and leave the nest earlier because of a higher risk of nest predation have lower survival rates after leaving the nest. Predation can be a major source of mortality in wild animal populations. When the risk of predation is variable, prey species are expected to show flexible developmental responses that reduce their risk of being killed by predators. For example, young birds may grow faster and leave the nest earlier when nest predation risk is high. However, flexible developmental responses at early life stages may be physiologically costly and increase mortality at later life stages. By simulating increased predation, the researchers will experimentally determine the effects of variable nest predation on nestling growth rate and timing of fledging for Dark-eyed Juncos. Each bird will be tagged with a radio transmitter to determine their fates after leaving the nest. The study will also address whether activity levels and behaviors of fledglings reduce mortality risks and compensate for physiological costs. Results will provide critical insights on the key factors that control the growth and decline of wild animal populations, and lead to more effective management of these populations. In addition, the project will involve mentoring of both undergraduate and graduate students, and will develop educational materials for high school students. Educational videos for school age children will also be created for a local science education center.This project tests the hypothesis that faster growth of Dark-eyed Juncos in response to nest predation risk compromises mobility and causes increased mortality risk at older life history stages. Researchers will use speakers to broadcast sounds of typical nest predators to increase the perception of nest predation risk by parents and offspring to examine its consequences for mortality after fledging. Preliminary data show that young nestlings in 'high risk' nests leave the nest with shorter wings and are less adept at flying, but it is unclear if these same individuals are predated more often after leaving. Just before the nestlings leave the nest the researchers will attach radio transmitters to aid in tracking. Data will be collected on how often and how far the young birds move around each day after they leave the nest; whether they hide more often in denser vegetation where predators, like hawks, have greater difficulty getting to them; and whether they actually are more likely to die. Results will advance our understanding of carryover effects from growth plasticity on offspring mortality during later life stages.