First report of cowbird parasitism on the black-capped gnatcatcher in western Mexico

摘要

In formation on cowbird parasitism in Mexico is rare. We report the successful fledging of a brown-headed cowbird (Molothrus ater) nestling by black-capped gnatcatchers (Polioptila nigriceps) in the tropical deciduous forest of the Chamela-Cuixmala Biosphere Reserve, western Mexico, in June 2001. We observed 2 additional gnatcatcher pairs feeding a single brown-headed cowbird fledging. Opportunistic observations of nests of other species and few captures of brown-headed cowbirds during 18 months of intensive mist-netting Suggested that cowbird abundance and parasitism was low in the reserve.