Brown-headed Cowbird

Molothrus ater 
Blackbird family (Icteridae)

Male (top image) – dark brown head, glossy black body. Female (bottom image) – grayish brown.

Habitat:
Forests, forest edges, brushy thickets, grasslands.

Nesting:
Brood parasite, lays eggs in other birds’ nests. A female cowbird may lay as many as 40 eggs during the nesting season. Eggs are white with brown spots and are usually larger than host eggs. Cowbird parasitism reduces the breeding success of many bird species because the female cowbirds remove host eggs or nestling cowbirds outcompete host nestlings. Cowbirds have been recorded as successfully parasitizing 200 bird species, including 49 bird species in Indiana.

Voice:

Song is a liquid “bublucomseee”.  Call is a high whistled “pseeesee”.

Name Origin:

Molothrus, Greek for “parasite” or “greedy person”; ater, Latin for “black” for the male’s dark plumage.

In the Nature Park:
Short-distance migrant, arrives in March or April. We take down the bird feeders at the Welcome Center in March so that we don’t encourage feeding the cowbirds. In the Nature Park, we have observed cowbird parasitism of Acadian Flycatcher nests (20% of nests are parasitized), Indigo Bunting nests (67% parasitized), and Wood Thrush nests (40% parasitized).

Photos: