Carolina Wren Nest Successfully Parasitized by House Finch

Abstract We report the first observation of a House Finch (Carpodacus mexicanus) successfully parasitizing a Carolina Wren (Thryothorus ludovicianus) nest. On 24 May 2005, we found a Carolina Wren nest in south-central Oklahoma containing four Carolina Wren eggs and two House Finch eggs. The House Finch eggs hatched and nestlings grew rapidly. The Carolina Wren eggs hatched but the young did not survive. We observed a House Finch fledgling with the adult Carolina Wrens the day after fledging.