The migration pattern of a monogamous shorebird challenges existing hypotheses explaining the evolution of differential migration

Differential migration by sex, where one sex migrates further than the other, occurs in many bird species. How this pattern evolves is however little understood. The first aim of this study was to investigate the extent of differential migration in the common ringed plover Charadrius hiaticula, breeding in southeast Sweden, and test three main hypotheses (the social dominance, body size and arrival time hypothesis) regarding the evolution of differential migration. Geolocators were used to derive spatiotemporal data and morphometrics were collected from the studied population. Males migrated 800 km farther compared to females, were marginally larger and there was no statistical difference in spring arrival between the sexes. In contrast to other studies none of the previously proposed hypotheses could account for the observed pattern. An additional finding was that both sexes arrive up to 1.5 months before egg laying, but males initiate territorial behaviour upon arrival. Based on these...许多鸟类均存在性别差异迁徙（differential migration）现象，即某一性别的迁徙距离长于另一性别。然而学界对该迁徙模式的演化机制仍知之甚少。本研究的首要目标为：针对瑞典东南部繁殖的环颈鸻（Charadrius hiaticula）种群，探究其性别差异迁徙的程度，并检验关于性别差异迁徙演化的三大核心假说——社会支配假说（social dominance hypothesis）、体型假说（body size hypothesis）与抵达时间假说（arrival time hypothesis）。本研究通过地理定位器（geolocator）获取时空数据，并采集了研究种群的形态测量学指标。结果显示，相较于雌性，雄性的迁徙距离远出800公里，体型仅略大于雌性，且两性的春季抵达时间无统计学差异。与其他研究不同的是，本研究观测到的迁徙模式无法被此前提出的任一假说所解释。另一项额外发现为：两性均会比产卵时间提前最多1.5个月抵达繁殖地，但雄性会在抵达后即刻开启领地行为。基于上述研究结果……