Behavioral Ecology and Ecophysiology Research group, University of Antwerp, Universiteitsplein1, 2610, Antwerp, Belgium.
Terrestrial Ecology Unit (TEREC), Ghent University, K.L. Ledeganckstraat 35, 9000, Ghent, Belgium.
Sci Rep. 2018 Mar 29;8(1):5391. doi: 10.1038/s41598-018-23605-x.
Sex-, size- or age-dependent variation in migration strategies in birds is generally expected to reflect differences in competitive abilities. Theoretical and empirical studies thereby focus on differences in wintering areas, by which individuals may benefit from avoiding food competition during winter or ensuring an early return and access to prime nesting sites in spring. Here, we use GPS tracking to assess sex- and size-related variation in the spatial behaviour of adult Lesser Black-backed Gulls (Larus fuscus) throughout their annual cycle. We did not find sex- or size-dependent differences in wintering area or the timing of spring migration. Instead, sexual differences occurred prior to, and during, autumn migration, when females strongly focussed on agricultural areas. Females exhibited a more protracted autumn migration strategy, hence spent more time on stopover sites and arrived 15 days later at their wintering areas, than males. This shift in habitat use and protracted autumn migration coincided with the timing of moult, which overlaps with chick rearing and migration. Our results suggest that this overlap between energy-demanding activities may lead females to perform a more prolonged autumn migration, which results in spatiotemporal differences in foraging habitat use between the sexes.
鸟类的迁徙策略在性别、体型或年龄上存在差异，通常反映了其竞争能力的不同。理论和实证研究因此集中在越冬地的差异上，个体可以通过避免冬季的食物竞争或确保春季及早返回和获得优质的筑巢地来从中受益。在这里，我们使用 GPS 跟踪来评估成年小黑背鸥（Larus fuscus）在其整个年度周期中的空间行为的性别和体型相关变化。我们没有发现越冬区或春季迁徙时间的性别或体型依赖性差异。相反，性别的差异出现在秋季迁徙之前和期间，此时雌性强烈关注农业区。与雄性相比，雌性表现出更持久的秋季迁徙策略，因此在中途停留地停留的时间更长，到达越冬地的时间晚了 15 天。这种生境利用的转变和持久的秋季迁徙与换羽的时间相吻合，换羽与育雏和迁徙重叠。我们的研究结果表明，这种能量需求活动之间的重叠可能导致雌性进行更持久的秋季迁徙，从而导致性别之间觅食生境利用的时空差异。
