Brown-headed Cowbird

Photographed on a walk in South Glenmore Park/Weaselhead on 7 June 2011. The Brown-headed Cowbird is a brood parasitic icterid - these words are from Wikipedia and new ones to me, lol!

"'Brood parasitic' means that it lays its eggs in the nests of other small passerines (perching birds), particularly those that build cup-like nests. The Brown-headed Cowbird eggs have been documented in nests of at least 220 host species, including hummingbirds and raptors. The young cowbird is fed by the host parents at the expense of their own young. Brown-headed Cowbird females can lay 36 eggs in a season. More than 140 different species of birds are known to have raised young cowbirds."

en.wikipedia.org/wiki/Brown-headed_Cowbird