Responses of Four Warbler Species to Playback of Their Two Song Types

Abstract

Many species of warblers singt wo different song types that apparently differ in motivation and function. Playback experiments were conducted in the field with American Redstarts, Chestnut-side Warblers, Black-throated Green Warblers, and Yellow Warblers. The first three species responded differentially to playback of their two song types. Redstarts and Chestnut-sided Warblers responded by approaching more closely to accented ending songs (AE) than to unaccented ending songs (UE) and Black-throated Green Warblers reacted more strongly to type A song than to type B. Yellow Warblers, which apparently have a graded song signal, did not differentiate, either by approaching or by song changes betweent wo very similar songs. Redstarts showed no age differences in response to AE and no difference in responsivenes bse tween experiments done early and later in the season, although song decreased during the later period. During playback redstarts, Black-throated Green Warblers, and Chestnut-sided Warblers tended to sing relatively more songs of the type being played back.