Variation in individual autumn migration and winter paths of Great Lakes red-headed woodpeckers (Melanerpes erythrocephalus)

Abstract

Migratory movements of facultative migrants are poorly understood due to their irregular and often unpredictable occurrence. However, tracking such movements is important for understanding population dynamics, informing annual cycle conservation plans, and identifying possible cues of facultative migration. We used pinpoint GPS tags to track autumn and winter movements of migratory red-headed woodpeckers (Melanerpes erythrocephalus) to better understand migration frequency, timing, and routes for birds breeding in managed oak savanna systems in the North American Great Lakes region. Proportions of individuals migrating differed between the two sites, with 72% of the Ohio population migrating, while no individuals in the Minnesota population migrated. Of the Ohio birds that migrated, their movements were highly variable in distance and direction but generally occurred south of the breeding site. Wintering sites ranged from 111 – 218 km from the breeding site. Cover types occupied during migration and wintering were almost exclusively small patches of closed-canopy hardwood forest within agricultural matrices. We documented one-time movements in migratory and non-migratory individuals during the year that have not previously been described in facultative migrants. We found no evidence of a harness or marker effect on proportions of individuals migrating, migration return rates, or annual survival regardless of migration.