Departament of Wetland Ecology, Estación Biológica de Doñana (EBD-CSIC), C/Américo Vespucio 26, E-41092, Seville, Spain.
Freelance, Independent Researcher, Seville, Spain.
Sci Rep. 2021 Jun 8;11(1):12044. doi: 10.1038/s41598-021-91378-x.
External factors such as geography and weather strongly affect bird migration influencing daily travel schedules and flight speeds. For strictly thermal-soaring migrants, weather explains most seasonal and regional differences in speed. Flight generalists, which alternate between soaring and flapping flight, are expected to be less dependent on weather, and daily travel schedules are likely to be strongly influenced by geography and internal factors such as sex. We GPS-tracked the migration of 70 lesser kestrels (Falco naumanni) to estimate the relative importance of external factors (wind, geography), internal factors (sex) and season, and the extent to which they explain variation in travel speed, distance, and duration. Our results show that geography and tailwind are important factors in explaining variation in daily travel schedules and speeds. We found that wind explained most of the seasonal differences in travel speed. In both seasons, lesser kestrels sprinted across ecological barriers and frequently migrated during the day and night. Conversely, they travelled at a slower pace and mainly during the day over non-barriers. Our results highlighted that external factors far outweighed internal factors and season in explaining variation in migratory behaviour of a flight generalist, despite its ability to switch between flight modes.
外部因素如地理和天气强烈影响鸟类迁徙，影响每日行程和飞行速度。对于严格依靠热上升的迁徙鸟类来说，天气解释了速度在季节和区域上的大部分差异。那些在翱翔和拍打飞行之间交替的飞行专家，预计对天气的依赖程度较低，每日行程很可能受到地理和内部因素（如性别）的强烈影响。我们通过 GPS 追踪了 70 只小隼（Falco naumanni）的迁徙，以估计外部因素（风、地理）、内部因素（性别）和季节在多大程度上解释了迁徙速度、距离和持续时间的变化，并确定了它们的相对重要性。我们的结果表明，地理和顺风是解释每日行程和速度变化的重要因素。我们发现，风解释了迁徙速度在季节上的大部分差异。在两个季节中，小隼都在跨越生态障碍，频繁地在白天和夜间迁徙。相反，它们在非障碍区以较慢的速度主要在白天迁徙。我们的结果强调，尽管飞行专家能够在飞行模式之间切换，但在解释其迁徙行为的变化时，外部因素远远超过内部因素和季节。
