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

这项研究调查了幼鸟是否生长得更快，更早离开鸟巢，因为被捕食的风险更高，离开鸟巢后的存活率是否更低。捕食可能是野生动物种群死亡的主要来源。当被捕食的风险可变时，被捕食物种预计会表现出灵活的发育反应，从而降低被捕食者杀死的风险。例如，当鸟巢被捕食的风险很高时，幼鸟可能会生长得更快，更早离开鸟巢。然而，早期生命阶段灵活的发育反应可能在生理上代价高昂，并增加后期生命阶段的死亡率。通过模拟捕食量的增加，研究人员将通过实验确定不同的巢穴捕食对黑眼幼鸟的雏鸟生长速度和羽化时间的影响。每只鸟都将被标记上无线电发射器，以确定它们离开鸟巢后的命运。这项研究还将探讨幼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。这些结果将为控制野生动物种群消长的关键因素提供关键的见解，并导致对这些种群的更有效管理。此外，该项目将包括对本科生和研究生的指导，并将为高中生开发教材。该项目还将为当地一家科学教育中心制作学龄儿童教育视频。该项目测试了这样一种假设，即黑眼幼崽在应对巢穴捕食风险时生长更快会影响行动能力，并在较年长的生活史阶段导致死亡风险增加。研究人员将使用扬声器播放典型鸟巢捕食者的声音，以增加父母和后代对鸟巢被捕食风险的感知，以检查其对羽毛未丰后死亡的影响。初步数据显示，在高风险鸟巢中的幼鸟离开鸟巢时翅膀较短，不太擅长飞行，但目前尚不清楚这些个体在离开后是否更经常被提前取食。就在雏鸟离开鸟巢之前，研究人员将安装无线电发射器来帮助追踪。将收集的数据包括这些幼鸟在离开鸟巢后每天活动的频率和距离；它们是否更频繁地躲在更密集的植被中，那里是鹰等捕食者更难接近它们的地方；它们是否真的更有可能死亡。这些结果将有助于我们理解生长可塑性对后代后期死亡率的影响。

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.