Brown-headed Cowbird Parasitizing
Chipping Sparrow Nest
This nest of a Chipping Sparrow, Spizella passerina in an ornamental cedar in front of our house contains two eggs of the brood parasitic Brown-headed Cowbird, Molothrus ater. The egg of the host species had been ejected and the pieces are shown here. Since egg laying by the female Brown-headed Cowbird is random it is likely that two individuals laid in the same host nest. We observed the Chipping Sparrow incubating for one day on 9 July 2011, after which it abandoned the nest.