How Do You Tell a Female Indigo Bunting from a Female Cowbird?

I think I had a female Indigo Bunting in my yard but it might be a cowbird. How can I tell? Patrick ~ East Lansing, MI

Little brown birds can sometimes be hard to identify when you just get a quick glance.

Both Indigo Buntings and Brown-headed Cowbirds live in similar habitats. The cowbird parasitizes or lays its eggs in indigos’ nests as well as other “host” species.

Both eat similar food and can be spotted at bird feeders.

Size is a good indicator. The Indigo Bunting’s shape and size (5 inches) is closer to a goldfinch, and the Brown-headed cowbirds’ (7 inches) is a little larger than a House Sparrow.

Color can sometimes help. Both females are a dull brown but the indigo is usually lighter. And if you look close you’ll see the indigo also has a two tone bill. The top is black and the bottom is a grey or tan. The cowbird has a black bill top and bottom.

Finally notice what birds are hanging around the bird you are trying to identify. Do you see a more distinguishable mate nearby? Cowbirds can also flock with blackbirds and starlings whereas indigos feed alone during the breeding season and with other indigos in the fall and winter.