Hot stops: timing, pathways, and habitat selection of migrating eastern whip-poor-wills

Although miniaturized data loggers allow new insights into avian migration, incomplete knowledge of basic patterns persists, especially for nightjars. Using GPS data loggers, this study examined migration ecology of the eastern whip-poor-will Antrostomus vociferus, across three migration strategies: flyover, short-stay, and long-stay. We documented migration movements, conducted hotspot analyses, quantified land cover within 1 and 5 km buffers at used and available locations, and modeled habitat selection during migration. From 2018–2020 we captured breeding whip-poor-wills from three study sites in Massachusetts and programmed GPS tags to collect data during fall and spring migration periods. Across 19 individual males (nine of them with repeated years of data), GPS tags collected 479 locations, where 30% were classified as flyover points, 33% as short-stays, and 37% as long-stay locations. We documented seasonal flexibility in migration duration, routes, and stopover locations among individuals and between years. Analyses identified hotspot clusters in fall and spring migration in the Sierra de Tamaulipas in Mexico. Land cover at used locations differed across location types at the 5 km scale, where closed forest cover increased and crop cover decreased for flyover, short-stay, and long-stay locations, and urban cover was lowest at long-stay locations. Discrete choice modeling indicated that habitat selection by migrating whip-poor-wills differs depending on the scale and migration strategy. For example, at the 5 km scale birds avoided urban cover at long-stay locations and selected closed forest cover at short-stay locations. We suggest that whip-poor-wills may use land cover cues at large spatial scales, like 5 km, to influence rush or stay tactics during migration.