FLIGHT CALLS OF WOOD-WARBLERS ARE NOT EXCLUSIVELY ASSOCIATED WITH MIGRATORY BEHAVIORS

Abstract

Wood-warblers (Parulidae) have species-specific flight calls given day and night in migration. These vocalizations are believed to maintain flocks and to stimulate migratory activity during migration. However, anecdotal evidence suggests that warblers also give flight calls during non-migratory periods. I examined use of flight calls during the nesting, fledgling, and wintering periods in 23 species of warblers to clarify the seasonal pattern of occurrence for this type of vocalization. Flight calls recorded during migratory and non-migratory periods were similar. The Nashville Warbler (Vermivora ruficapilla) was the only species that gave flight calls during the nesting period and it did so rarely. Half of the species surveyed during fledgling periods and nearly half (47.8%) of the species surveyed during wintering periods gave flight calls. Calls per minute rates during the nesting period were an order of magnitude lower than in the fledgling and wintering periods. Flight calls are most common during migration but this vocalization in warblers is not limited to migratory periods. Flight calls may have functions additional to those during migration.