Departamento de Ecología/IMEM Ramon Margalef, Universidad de Alicante, Alicante, Spain.
Grupo Local SEO-Alicante, SEO/BirdLife, Alicante, Spain.
Sci Rep. 2022 Feb 21;12(1):2943. doi: 10.1038/s41598-022-06912-2.
Clues used by migrant birds to select sites for stopover are much less known than their reasons for leaving. Habitat characteristics and geographical location may affect the decision to use an island as a stopover site in different ways for different species. Thus, abundance and composition of migrants may be expected to differ between islands. Using standardized ringing from 9 western Mediterranean islands we evaluate drivers of abundance of trans-Saharan migrant passerines, specifically the role of species continental abundance, island characteristics and geographical location. Although continental abundance is a main driver of migrant composition on all islands migrant composition differs between them. Redundancy analysis and species response models revealed that the main drivers were distance to the nearest land toward the south, which has a positive effect on the number of migrants of most species, and island area, which appears as an important cue used for selecting a stopover island. Species whose abundance is positively related to island area have more pointed wings while species affected by distance to land toward the south have relatively more rounded wings. This suggests a hypothesis on the mechanism that may generate differences in passerine migrant composition between islands based on better efficiency of more pointed wings for long-distance flight.
候鸟选择中途停留地点的线索比它们离开的原因知之甚少。栖息地特征和地理位置可能以不同的方式影响不同物种选择岛屿作为中途停留地的决定。因此，不同岛屿上的候鸟数量和组成可能存在差异。我们使用来自 9 个西地中海岛屿的标准化鸣禽环志数据，评估了撒哈拉以南候鸟的丰度的驱动因素，特别是物种大陆丰度、岛屿特征和地理位置的作用。尽管大陆丰度是所有岛屿上候鸟组成的主要驱动因素，但它们之间的候鸟组成存在差异。冗余分析和物种响应模型表明，主要驱动因素是距最南端最近的陆地的距离，这对大多数物种的候鸟数量有积极影响，而岛屿面积则是选择中途停留岛屿的重要线索。与岛屿面积呈正相关的物种具有更尖的翅膀，而受最南端陆地距离影响的物种具有相对更圆的翅膀。这表明了一种基于更尖的翅膀在长距离飞行中具有更高效率的机制，可能会产生岛屿间鸣禽迁徙组成的差异的假说。
