An experimental examination of the influence of energetic condition on the stopover behavior of a Nearctic–Neotropical migratory songbird, the American Redstart (Setophaga ruticilla)

Abstract

ABSTRACT Late arrival on the breeding grounds has been associated with reduced fitness in migratory birds. Because migratory stopover accounts for the majority of time spent on migration, how individuals respond to both exogenous and endogenous factors associated with stopover will influence the pace of migration and arrival timing on the breeding grounds. Among the most important endogenous factors, body condition (i.e. fat stores) is expected to influence both movement behavior and departure decisions of individual migrants during stopover. In a novel experiment, we manipulated the condition of after-second-year (adult) male American Redstarts (Setophaga ruticilla) captured during spring migratory stopover and radio-tracked all individuals after release using a passive automated telemetry array and conventional hand tracking. After accounting for the positive effect of tailwind and capture date on departure probability, we demonstrated that body condition influenced both the movement behavior of individ...