Brown-headed Cowbird
Molothrus ater
Family Icteridae

A small, American blackbird, the Brown-head Cowbird is called “cowbird” because of its habit of following cows in order to eat the insects they stir up as they ruminate. 

Identifying Traits (male):

  • Dark brown head and black body
  • Short, sparrowlike bill
  • Medium-long tail
  • Feeds with tail lifted up
  • Juvenile:  can be pale gray or a bizarre mosaic of brown and black
  • Size: 18 cm (7.5”)
  • Weight: 44 g (1.5oz)


Identifying Traits (female):

  • Pale gray body and head with a light colored throat
  • Juvenile: lighter gray than adult, soft breast streaks
Adult male  

Similar Species: A young starling has a longer bill and shorter tail.

Voice: The cowbird’s song is a bubbly, gurgling glug-glug-gleeee, often repeated.  The flight call is a high whistle followed by two rapid notes, weee-titi.  When flocking or disturbed, cowbirds utter a sharp chuck note.

Habitat: Cowbirds favor any relatively open space with abundant insect life.  Thus, they are often found on farms and in barnyards, as well as by roadsides and the edges of wooded areas.

Range: The brown-headed cowbird is a year-round resident from Vermont south to Virginia and westward.  Cowbirds are generally found north of this band only in the breeding season and are only found south of it during the winter.

Interesting Facts: Brown-headed cowbirds are nest parasites – the female lays her egg in the nest of another bird.  The host bird will often accept and incubate the larger egg as one of its own.  Once the egg hatches, the young cowbird grows quickly and forces it smaller nestmates out of the nest.  The host bird will continue to feed the cowbird chick (which may be twice the host’s size) until it grows too large to fit in the nest and flies off.



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