Connectivity of wood thrush breeding, wintering, andmigration sites based on range-wide tracking

Abstract

Many migratory animals are experiencing rapid population declines, but migration data withthe geographic scope and resolution to quantify the complex network of movements between breedingand nonbreeding regions are often lacking. Determining the most frequently used migration routes andnonbreeding regions for a species is critical for understanding population dynamics and making effectiveconservation decisions. We tracked the migration of individual Wood Thrushes(Hylocichla mustelina)(n=102) from across their range with light-level geolocators and, for the first time, quantified migration routesand wintering regions for distinct breeding populations. We identified regional and species-level migratoryconnectivity networks for this declining songbird by combining our tracking results with range-wide breedingabundance estimates and forest cover data. More than 50% of the species occupied the eastern winteringrange (Honduras to Costa Rica), a region that includes only one-third of all wintering habitat and that isundergoing intensive deforestation. We estimated that half of all Wood Thrushes in North America migratesouth through Florida in fall, whereas in spring approximately 73% funnel northward through a narrow spanalong the central U.S. Gulf Coast (88–93°W). Identifying migratory networks is a critical step for conservationof songbirds and we demonstrated with Wood Thrushes how it can highlight conservation hotspots for regionalpopulations and species as a whole