Mite-filled cyst on a Brown-headed Cowbird (Molothrus ater) in Florida, USA.

Conventional oil and natural gas infrastructure increases brown-headed cowbird (Molothrus ater) relative abundance and parasitism in mixed-grass prairie

The rapid expansion of oil and natural gas development across the Northern Great Plains has contributed to habitat fragmentation, which may facilitate brood parasitism of ground-nesting grassland songbird nests by brown-headed cowbirds (Molothrus ater), an obligate brood parasite, through the introduction of perches and anthropogenic edges. We tested this hypothesis by measuring brown-headed co...

Brown-headed Cowbird (molothrus Ater) Parasitism on Warbling Vireos (vireo Gilvus) in Southwest Colorado Catherine

A8s~~nc~.-From May through July, 1993-1998 and 2001, effects of Brown-headed Cowbird (Molothrus ater) parasitism on 36 Warbling Vireo (Vireo gilvus) nests were documented in southwest Colorado. Overall parasitism was 75.0% and was the major source of nest failure. Among vireo nests that were not depredated, a significantly lower proportion of parasitized nests (10.2%) than nonparasitized nests ...

FEMALE INFLUENCE IN THE BROWN-HEADED COWBIRD (Molothrus ater): AN INVESTIGATION OF EMERGING SOCIAL ECOLOGIES

Male Brown-headed Cowbird Attacks and Kills a Nestling

I observed a male Brown-headed Cowbird (Molothrus ater) attack and kill a nestling of an unidentified passerine in a grassland field in Day County, South Dakota, in June 2000. The killing or removal of nestlings by female cowbirds has been reported by others, but this behavior has not been documented previously in male cowbirds. Received 8 October 2002, accepted 3 March 2003. Female Brown-heade...

High offspring survival of the brown-headed cowbird in an invaded habitat

The brood parasitic brown-headed cowbird (Molothrus ater) is considered an important threat to bird conservation in North America because it reduces the reproduction of its numerous host species. Prior to the colonisation of America by Europeans, the cowbird was largely confined to the North American prairie region, but it has since invaded forests and other habitats and is now one of the conti...