Year-round behavioural and ecological influences on the function and evolution of ornamental plumage in migratory birds

几个世纪以来，鸟类迁徙一直吸引着研究人员和自然历史学家，因为它的规模和令人难以置信的距离。以北极燕鸥为例，每年从北极北部的繁殖地到南极海域，往返行程近三万公里。然而，同样引人注目的是这种红喉蜂鸟24小时穿越墨西哥湾的飞行。这些迁徙旅程在数量和持续时间上都令人震惊，每年有数十亿人旅行数千公里。对于研究候鸟的研究人员来说，一个主要的挑战是了解这些鸟类的进化和生态，尽管这种现象广泛而普遍，但我们仍然对影响它们繁殖期以外的生活史和行为的因素知之甚少。事实上，我们对候鸟的绝大多数了解都来自于对欧亚大陆和北美温带繁殖地的研究，很少有研究涉及候鸟的越冬和迁徙生态。然而，全年跟踪个体的新技术为今后研究候鸟的行为和生态提供了有希望的途径。例如，鸟类羽毛和爪子中的稳定同位素（如C，N和H等元素的稳定形式，这些元素在环境中可预测地变化，并沿着食物链向上移动以融入鸟类组织）可以帮助确定换羽的位置或鸟类过冬的栖息地的质量。此外，背包式设备，如光水平地理定位器（数据记录器连接到鸟类记录环境光水平），使研究人员能够估计个人的纬度和经度在每年的旅程。在这项研究中，我的目的是研究功能和进化的五颜六色的装饰羽毛在候鸟全年和跨大陆。这项工作将是第一个将联合收割机稳定同位素分析与光级地理定位器相结合，以研究在整个年度周期中发生的事件如何影响自由生活的候鸟装饰羽毛颜色的演变。

Bird migration has captivated researchers and natural historians for centuries, both because of its sheer magnitude and the incredible distances travelled. Take, for instance, the trans-continental journey of the Arctic tern, who travels yearly from its breeding grounds in the Arctic north to the Antarctic seas - a round-trip journey of nearly 30,000 kilometers. No less remarkable, however, is 24-hour trans-Gulf of Mexico flight of the diminutive ruby-throated hummingbird. These migratory journeys are staggering in both number and duration, with billions of individuals traveling thousands of kilometers every year. For researchers studying migratory birds, a major challenge is understanding the evolution and ecology of these birds when, despite the vastness and ubiquity of the phenomenon, we still know little about the factors that influence their life history and behaviour outside of the breeding period. Indeed, the vast majority of our knowledge of migratory birds comes from studies conducted on the temperate breeding grounds in Eurasia and North America, with very few studies addressing the over-wintering and migratory ecology of migratory birds. Yet, new technologies for tracking individuals throughout the year offer promising avenues for future research on the behaviour and ecology of migratory birds. For example, stable-isotopes (stable forms of elements such as C, N, and H that vary predictably in the environment and travel up the food chain to be incorporated in bird tissues) in bird feathers and claws can help determine the location of moult or the quality of habitat a bird spent the winter in. Additionally, backpack-style devices, such as light-level geolocators (data loggers attached to the birds that record ambient light levels) are allowing researchers estimate individual latitude and longitude over the yearly journey. In this study, I aim to examine the function and evolution of colourful ornamental plumage in migratory birds throughout the year and across continents. This work will be the first to combine stable isotope analysis with light-level geolocators to study how events occurring throughout the annual cycle influence the evolution of ornamental plumage colouration in free-living migratory birds.