Long-term effects of habitat quality on juvenile fitness along contrasting environmental gradients

我的研究计划的长期目标是了解人为应激源如何导致候鸟数量下降。数十种北美物种几十年来一直在急剧减少，其中许多现在被加拿大列为濒危物种。候鸟保护面临的最大挑战之一是确定经过充分研究的繁殖种群与它们生命周期中其他威胁之间的联系。2009年，我的实验室在《科学》杂志上发表了一项开创性的研究，首次使用微型跟踪设备绘制了鸣鸟从开始到结束的迁徙过程，这引发了我们对鸣鸟迁徙生态和保护的理解革命。然而，知识上的一个关键差距仍然存在，因为人们对候鸟幼体存活的了解很少，但预计会对种群动态产生很大影响。后代在孵化后一个月左右就会离开父母的领地，活动能力变得越来越强，很难被追踪，在迁徙后，很少有人回到离出生地点足够近的地方，以便研究人员发现。环境压力预计将对独立的青少年产生重大影响，因为它们最初的觅食效率很低，但它们必须建立脂肪储备，为首次秋季迁徙做准备，这次迁徙将跨越数千公里的陌生地形。*我的研究计划很新颖，因为我将通过在覆盖安大略省西南部的新的自动遥测接收器阵列中部署新的长期(一年)编码无线电发射器来跟踪青少年。通过将人工跟踪和自动跟踪相结合，我的学生将测试栖息地质量如何影响幼体条件、生存、分散和秋季迁徙的开始，我们将在大约100,000平方公里的阵列内重新定位明年春天返回的新兵。这项新颖的技术将允许我们测试一系列假设，以了解栖息地质量如何以及为什么会影响候鸟的短期和长期幼体健康。较差的栖息地质量预计会降低雏鸟的身体状况，并对幼鸟的健康产生长期的负面影响。我们将根据两种不同的环境梯度(森林碎片化、农业集约化)来评估这些发展影响的性质和持续时间，这两种环境梯度的潜在生态压力来源不同。我们的结果将通过种群建模场景直接为栖息地管理决策提供信息，这些场景清楚地识别栖息地丧失和碎片化对候鸟的影响。**

The long term objective of my research program is to understand how anthropogenic stressors contribute to population declines of migratory songbirds. Dozens of North American species have been in steep decline for decades and many are now designated as Species at Risk in Canada. One of the biggest challenges in migratory songbird conservation has been determining the link between well-studied breeding populations and threats elsewhere in their life cycle. In 2009, my lab published a ground-breaking study in Science that used miniaturized tracking devices to map the start-to-finish migration of songbirds for the first time, and this triggered a revolution in our understanding of songbird migration ecology and conservation. However, a critical gap in knowledge remains because juvenile survival is poorly understood in migratory songbirds yet is expected to have a large impact on population dynamics. Offspring disperse away from their parent's territory a month or so after hatching, become increasingly mobile and difficult to track, and after migration few return close enough to their natal site to be detected by researchers. Environmental stressors are expected to have a big impact on independent juveniles because their foraging efficiency is initially low yet they must build fat reserves to prepare for their inaugural fall migration that is thousands of kilometers across unfamiliar terrain.***My research program is novel because I will track juveniles by deploying new long-lasting (>1 year) coded radio-transmitters within a new array of automated telemetry receivers that blankets southwestern Ontario. By combining manual and automated tracking, my students will test how habitat quality affects juvenile condition, survival, dispersal and onset of fall migration and we will re-locate recruits that return the next spring within the ~100,000 square kilometer array. This novel technology will allow us to test a series of hypotheses for how and why habitat quality impacts short-and long-term juvenile fitness in migratory songbirds. Poor habitat quality is expected to reduce nestling body condition and carry over to have long-lasting and negative effects on juvenile fitness. We will evaluate the nature and duration of these development effects along two contrasting environmental gradients (forest fragmentation, agricultural intensification) that differ in their underlying ecological stressors. Our results will directly inform habitat management decisions through population modelling scenarios that clearly identify the consequences of habitat loss and fragmentation on migratory songbirds.**