Intratropical migration of a Nearctic-Neotropical migratory songbird (Catharus fuscescens) in South America with implications for migration theory

Abstract

Abstract:Recent advances in tracking technology have revealed significant intratropical movement of Nearctic–Neotropical migratory songbirds during their non-breeding season. We report the movement of 25 veeries (Catharus fuscescens) over multiple seasons (2009–2013) through equatorial rain forests of South America. Veeries initially settled on the Brazilian Shield geological formation but undertook an intratropical migration to a second South American region in January, February or March. Consequently, our study is the first to track individual forest passerines to document an annual migration from the Brazilian Shield to the Guiana Shield and into lowland regions of Amazonia. The movement and settlement patterns showed no spatiotemporal relationships with Nearctic–Neotropical migration, remained in accordance with the flood pulse of the Amazon basin, and were spatially and temporally complex suggesting relatively ancient ancestral origins. The ability to isolate the migration event from Nearctic–Neotropical migration is an important contribution to the ongoing discourse regarding the evolution of trans-hemispheric migration in the genus Catharus.