EFFETS ON BROWN-HEADED COWBIRDS AND PREDATORS ON THE NESTING SUCCESS OF YELLOW WARBLERS IN SOUTHWEST COLORADO

摘要

We studied the effects of brood parasitism by Brown-headed Cowbirds(Molothrus ater) and predators on the reproductive biology of Yellow Warblers(Dendroica petechia) in La Plata County, Colorado, 1992-1996. Overall, 36/100 of Yellow Warbler nests (n =66)were Parasitized by Brown-headed Cowbirds. Although parasitized and nonparasitized nests were Equally likely to fledge at least one warbler, in nonparasitized nests, warblers has larger Clutches, hatched more young, and tended to fledge more young.