Early Vocalizations of the Brown-headed Cowbird and Three Host Species

Abstract
Vocalizations of nestling and newly fledged Brown-headed Cowbirds Molothrus ater from eight nests were recorded, analyzed and compared with those of the host''s young to determine if Cowbirds mimic their nest mates. Sonagrams showed that vocalizations of Cowbird, Chipping Sparrow Spizella passerina, Song Sparrow Melospiza melodia and Yellow Warbler Dendroica petechia were distinctly different in structure. The results indicated that young Cowbirds do not mimic the vocalizations of their foster species; and thus it appears that acceptance by the host is not dependent solely upon vocalizations by Cowbird young.