Evaluation of sex differences in the stopover behavior and postdeparture movements of wood-warblers

Sex-specific behaviors underlying avian protandry, where males arrive at breeding areas earlier than females, are still poorly understood for most species. We tested for sex-specific stopover behavior of Neotropical-Nearctic wood-warblers (Parulidae) at a stopover site on Lake Erie, Ontario, using radio telemetry and analysis of blood plasma. The sex differences we found were subtle and related to diel activity, and so likely do not contribute to protandry in a consistent way.