Mechanisms of En Route Habitat Selection: How Do Migrants Make Habitat Decisions during Stopover?

Abstract

Evidence reveals that habitat selection occurs during migration, but little is known about how migrants made decisions about habitat use during stopover.Although most nocturnally migrating birds end their migratory flight well before dawn, selection of habitat probably occurs during daylight hours.Possibly "morning flights" represent efforts to explore suitable habitats in which to rest and forage.Choice of habitat probably consists of a sequence of hierarchically ordered decisions that depend on different criteria.When migrants arrive they may settle in response to gross habitat features such as vegetation density, then search for resources based on more subtle habitat features or the behavior of other migrants.We used radio-telemetry to study the movement pattern of Summer Tanagers (Piranga rubra) during stopover.Use of habitat and pattern of movement differed between fat and lean individuals.Lean birds were more active, displayed a pattern of movement more consistent with exploration, and visited more habitat types than did fatter birds.