Density of Neotropical Bird Migrants is Highest at Stopover Sites with an Intermediate Amount of Forest in the Surrounding Landscape and a Low Proportion of Forest in Conifer

Abstract

Some nearctic-neotropical migrant forest-breeding songbirds have suffered large population declines in recent decades. Declining availability of high-quality habitat where birds refuel during the long migration may be contributing to these declines. Our objective was to identify landscape attributes that make sites likely to be used as stopover sites during fall migration. We sampled birds at 37 sites in southeastern Ontario, Canada. Bird density was highest at sites with an intermediate amount of surrounding forest within 2 km, and where deciduous trees were in higher proportions in surrounding forests within 8 km. These results suggest that birds are attracted to landscapes with an intermediate amount of forest cover. Their densities may decrease at higher forest amounts due to dilution, conifer avoidance, or reduced edges for foraging. Our study highlights the importance of retaining sites with around 50% forest cover, particularly deciduous forest, as stopover habitat for migrating songbirds.