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Prolonged stopover and consequences of migratory strategy on local-scale movements within a regional songbird staging area

Smetzer, Jennifer R., King, David I.
The Auk 2018 v.135 no.3 pp. 547-560
Setophaga, Vireo, automation, breeding, coasts, landscapes, migratory behavior, radio telemetry, songbirds, North America
Geolocator technology has recently demonstrated that many songbird species exhibit prolonged stopovers during migration that may be analogous to the staging behavior typically attributed to shorebirds. Although staging areas can act as ecological bottlenecks, there is little information on how or why songbirds engage in prolonged stopover and whether this behavior differs among individuals. We used automated radio telemetry along the eastern coastline of North America to compare stopover and migration behavior of Blackpoll Warblers (Setophaga striata) and Red-eyed Vireos (Vireo olivaceus), species that differ markedly in migratory strategy during fall migration. We also tested whether migratory behaviors differed within each species by capture date or breeding origin. Prolonged stopover was more common and longer for Blackpoll Warblers, which suggests that it may be a particularly adaptive behavior for supporting the transatlantic endurance flights they make from the region. Both species made prolonged stopovers that consisted of extended stops at one site, as well as multiple shorter stops within a geographically broad stopover landscape. Later migrants of both species and Blackpoll Warblers from more northwestern origins exhibited migratory traits consistent with a time-minimization strategy.