An assay to investigate factors influencing initial orientation in nocturnally fledging seabirds.

The first solitary migration of juvenile birds is difficult to study because of a low juvenile survival rates and sometimes long delays in return to the breeding grounds. Consequently, little is known about this crucial life event for many bird species, in particular the sensory guidance mechanisms facilitating the first migratory journey. Initial orientation during the first migration is a key measure to investigate these mechanisms. Here, we developed an assay to measure initial orientation as flight direction upon first take-off in nocturnally fledging juvenile seabirds. We dorsally deployed a coloured LED on juvenile birds to allow researchers to observe the vanishing bearings of individuals as they flew out to sea. Additionally, we co-deployed either a small Neodymium magnet or glass bead (control) on top of the bird’s head to investigate the use of magnetoreception, previously unexplored in this early life stage.

 

We used this assay to observe the first flight of Manx shear...

幼鸟的首次单独迁徙因幼鸟存活率偏低，且有时返回繁殖地会出现长时间延迟，故难以开展相关研究。因此，针对众多鸟类的这一关键生命事件，目前相关认知仍较为匮乏，尤其是助力首次迁徙旅程的感官引导机制。首次迁徙期间的初始定向是探究此类机制的核心指标。本研究开发了一种测定方法，用于测量夜间离巢的幼海鸟首次起飞时的飞行方向，以此表征其初始定向。我们在幼鸟背部安装了发光二极管（LED），以便研究人员观测个体飞向海洋时的消失方位。此外，我们在幼鸟头顶同时安装小型钕磁铁（Neodymium magnet）或玻璃珠（glass bead，对照组），以探究磁感受（magnetoreception）的作用——这一机制在该生命早期阶段此前尚未被探索过。

我们借助此测定方法观测了曼克斯剪水鹱（Manx shear...）的首次飞行。