Dissertation Research: Evolution of Altitudinal Migration in Tropical Birds: A Test of Three Hypotheses

论文研究：热带鸟类海拔迁徙的演化：三个假设的检验

• 批准号: 0410531
• 负责人: Judith Bronstein
• 金额: $ 1.2万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-15 至 2006-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0410531&HistoricalAwards=false
• 关键词: Dissertation; Research; Evolution; Altitudinal; Migration

Many animals undertake spectacular annual migrations, across distances ranging from only a few kilometers to transpolar voyages. A great deal is now known about the routes these animals follow, and the cues that initiate migratory behavior. However, why some species migrate and others never do has remained a mystery. Many possibilities have been suggested, but rigorous tests have been lacking. This project will test predictions of three hypotheses for why some but not all fruit-eating tropical birds migrate up mountain ranges to breed, and back downhill after breeding: the fruit availability hypothesis (migratory birds track seasonal availability of fruits); the arthropod availability hypothesis (migratory birds track seasonal availability of arthropods, a minor but critical component of their diets); and the nest predation hypothesis (birds migrate uphill to escape high densities of predators that feed upon eggs and fledglings). The research will be conducted along an elevational gradient in protected tropical forest on the Atlantic side of Costa Rica, where patterns of bird movement and both bird and plant diversity are unusually well-known. The work will focus on one typical and abundant species, the white-ruffed manakin (Corapipo altera). Tests of the hypotheses involve determining (a) what foods are available, (b) what manakins feed upon, and (c) how often predators attack artificial nests, at different elevations and at different times of year. Beyond shedding light on a renowned biological mystery, understanding why birds migrate should illuminate the consequences of habitat variation for tropical organisms. This work ultimately should suggest the likely impacts of human-caused habitat alterations, including climate change and deforestation, in these threatened landscapes.

许多动物每年都会进行壮观的迁徙，从几公里到跨极地的距离不等。现在人们对这些动物遵循的路线以及引发迁徙行为的线索有了很多了解。然而，为什么有些物种会迁移，而另一些物种却永远不会迁移，这仍然是一个谜。人们提出了许多可能性，但缺乏严格的测试。 这个项目将测试三个假设的预测，为什么一些但不是所有的食果热带鸟类迁移到山脉繁殖，并在繁殖后返回下坡：水果可用性假设（候鸟跟踪水果的季节性供应）;节肢动物供应假说（候鸟追踪节肢动物的季节性供应，这是它们饮食的一个次要但重要的组成部分）;以及巢穴捕食假说（鸟类向山上迁徙，以躲避以蛋和幼鸟为食的高密度捕食者）。 这项研究将在哥斯达黎加大西洋一侧受保护的热带森林中沿着一个海拔梯度进行，那里的鸟类运动模式以及鸟类和植物的多样性都是非常有名的。这项工作将集中在一个典型的和丰富的物种，白皱侏儒鸟（Corapipo altera）。假设的测试包括确定（a）有什么食物，（B）侏儒鸟以什么为食，以及（c）捕食者在不同海拔和一年中不同时间攻击人工巢穴的频率。除了揭示著名的生物学之谜之外，了解鸟类迁徙的原因还应该阐明热带生物栖息地变化的后果。这项工作最终应该表明人类造成的栖息地改变可能产生的影响，包括气候变化和森林砍伐，在这些受威胁的景观。