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，这既是因为它的巨大规模，也是因为它旅行的距离令人难以置信。以北极燕鸥的跨洲之旅为例，它每年从北极北部的繁殖地到南极海-往返近3万公里。然而，同样引人注目的是，这种小巧的红喉蜂鸟24小时飞越墨西哥湾。这些迁徙之旅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，我们对候鸟的大部分知识来自于在欧亚大陆和北美温带繁殖地进行的研究，很少有研究涉及候鸟的越冬和候鸟生态。然而，全年跟踪个体的新技术为未来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(C、N和H等元素的稳定形式，在环境中可预测地变化，并沿食物链向上移动，并入鸟类组织)可以帮助确定鸟类越冬的蜕皮位置或栖息地的质量。此外，背包式设备，如光级地理定位器(连接到鸟类上的数据记录器，记录环境光级)使研究人员能够估计每年旅程中的个人纬度和经度。在这项研究中，我的目的是研究彩色观赏羽毛在全年和跨洲候鸟中的功能和演变。这项工作将首次将稳定同位素分析与光水平地理定位仪相结合，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的装饰羽毛着色的演变。

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.