High spatiotemporal overlap in the non-breeding season despite geographically dispersed breeding locations in the eastern whip-poor-will (Antrostomus vociferus)

Aim: A full annual cycle approach to conservation and understanding of regional population trends requires an understanding of migratory connectivity. We present tracking data on the eastern whip-poor-will (Antrostomus vociferus), a Neotropical migrant that has declined by 70% in recent decades. When and where populations of this species are limited throughout the annual cycle is poorly understood. Methods: We utilized data from 52 archival GPS tags from five breeding areas covering a 9.5-degree latitudinal span (similar to 1000 km) of the whip-poor-will breeding range in the summers of 2017 and 2019. We identified migratory routes and spatiotemporal bottlenecks, stopover and wintering locations, calculated migratory connectivity throughout migration and on the wintering grounds and tested predictions for three latitudinal connectivity patterns. Results: Whip-poor-wills circumvented the Gulf of Mexico, and populations across a large latitudinal gradient came together in eastern Texas in early October, resulting in decreased connectivity throughout migration. Breeding-winter migratory connectivity was low (MC = 0.22 +/- 0.12), with extensive overlap of core wintering areas in southern Mexico and Guatemala. The overlap of wintering areas by individuals from dispersed breeding latitudes suggests that whip-poor-wills most closely resemble telescopic migrants. Main conclusions: Circumventing the Gulf of Mexico influenced connectivity in the whip-poor-will, funnelling individuals into a small region in eastern Texas in migration and likely influencing breeding-winter connectivity. Thus, geographically dispersed breeding populations overlap in space and time during migration and winter, and non-breeding season conditions affecting populations (both positively and negatively) impact individuals from across the core breeding range. For example, extensive deforestation occurring in the whip-poor-will's core wintering area likely impacts individuals from all five deployment locations. We demonstrate that combining multiple indices of spatiotemporal cohesion is critical to fully understand how migratory animals are distributed in the non-breeding season.