Data from: Tracking the migration of a nocturnal aerial insectivore in the Americas

Background: Populations of Eastern Whip-poor-will (Antrostomus vociferous) appear to be declining range-wide. While this could be associated with habitat loss, declines in populations of many other species of migratory aerial insectivores suggest that changes in insect availability and/or an increase in the costs of migration could also be important factors. Due to their quiet, nocturnal habits during the non-breeding season, little is known about whip-poor-will migration and wintering locations, or the extent to which different breeding populations share risks related to non-breeding conditions. Results: We tracked 20 males and 2 females breeding in four regions of Canada using geolocators. Wintering locations ranged from the gulf coast of central Mexico to Costa Rica. Individuals from the northern-most breeding site and females tended to winter furthest south, although east-west connectivity was low. Four individuals appeared to cross the Gulf of Mexico either in spring or autumn. On southward migration, most individuals interrupted migration for periods of up to 15 days north of the Gulf, regardless of their subsequent route. Fewer individuals showed signs of a stopover in spring. Conclusions: Use of the southeastern United States for migratory stopover and a concentration of wintering locations in Guatemala and neighbouring Mexican provinces suggest that both of these regions should be considered potentially important for Canadian whip-poor-wills. This species shows some evidence of both "leapfrog" and sex-differential migration, suggesting that individuals in more northern parts of their breeding range could have higher migratory costs.

研究背景：东部鞭夜鹰（Eastern Whip-poor-will, Antrostomus vociferous）的整体分布种群均呈下降趋势。尽管这一现象可能与栖息地丧失相关，但诸多迁徙性空中食虫鸟类的种群下降案例表明，昆虫资源量变化以及/或迁徙成本上升也可能是关键影响因素。由于该物种在非繁殖期习性隐秘且多在夜间活动，学界对其迁徙规律、越冬地点，以及不同繁殖种群在非繁殖期所面临的风险共享程度均所知甚少。

研究结果：本研究通过地理定位器（geolocators）追踪了加拿大4个繁殖区域内的20只雄性与2只雌性繁殖个体。其越冬范围从中墨西哥湾沿岸延伸至哥斯达黎加。来自最北部繁殖区域的个体与雌性个体，其越冬地点往往更靠南，尽管种群间的东西向连通性较低。共有4只个体在春季或秋季跨墨西哥湾迁徙。在南行迁徙过程中，无论后续迁徙路线如何，多数个体都会在墨西哥湾以北地区暂停迁徙，停留时长可达15天；而春季迁徙期间出现中途停歇迹象的个体则相对较少。

研究结论：美国东南部被用作迁徙中途停歇地，且多数越冬个体集中在危地马拉及邻近的墨西哥省份，这表明这两个区域均可能对加拿大东部鞭夜鹰种群具有潜在重要意义。该物种同时表现出跳跃式迁徙（leapfrog migration）以及性别差异化迁徙的特征，这意味着繁殖分布更靠北的个体可能需要承担更高的迁徙成本。