Brown-headed Cowbird

Molothrus ater

Marshall Iliff

Brown-headed Cowbirds are medium-sized birds, growing up to eight inches long. Male cowbirds have a black body with a brown head. Females are plain grayish-brown all over.

This bird lives in fields, forest edges, parks, and thickets.

Brown-headed Cowbirds eat seeds from weedy plants, as well as insects, including grasshoppers, crickets, and beetles. They will also eat other small creatures they can catch, such as spiders.

Copyright, Dan Sudia

What this bird is best known for is its breeding habits. These birds do not build a nest or raise their young. Instead, after mating, female cowbirds lay their eggs in the nests of other birds. Then they fly away, never to return.

Brown-headed Cowbirds depend on the owners of the nests to raise their young. The host bird will sit on the cowbird's eggs as well as its own. When baby cowbirds hatch, the host parents will feed them along with their own young. Cowbirds tend to grow quickly. This means they eat more food that was intended for the other baby birds. Sometimes they even push the young of the host parents out of the nest. These behaviors make the Brown-headed Cowbird a parasite.

There are hundreds of different species of birds that have raised cowbirds, including Northern Cardinal, Red-winged Blackbird, Eastern Phoebe, Common Yellowthroat, Common Grackle, Wood Thrush, and Indigo Bunting. Some birds recognize the eggs as not being their own. American Robins and Gray Catbirds, for instance, will throw the eggs out. Some birds build more nest on top of the cowbird egg. However, most birds do mistakenly raise the young cowbirds until they can make it on their own.

Copyright, Greg Gough

Brian D. Beer, Smithsonian National Museum of Natural History

The picture to the left shows Brown-headed Cowbird eggs in a Northern Cardinal nest. Can you spot which eggs are cardinal and which ones are cowbird?

Predators of Brown-headed Cowbirds include hawks, owls, raccoons, squirrels, and snakes.

Brown-headed Cowbirds travel in large winter flocks with other species, including Common Grackles and Red-winged Blackbirds.

Additional Media

Description
Type
Credit
Brown-headed Cowbird Song
Sound
Richard Goodlet
Brown-headed Cowbird Chick Pushing Indigo Bunting Nestling Out of Nest
Link to Video
Don Dearborn
Download Quicktime if you are unable to play video.

Relationships in Nature:

PREY/FOOD
PREDATORS
SHELTER
OTHER

Differential Grasshopper

Red-tailed Hawk

Smooth Sumac

Northern Cardinal H

Field Cricket

Sharp-shinned Hawk

Highbush Blueberry

Common Grackle H

Common Black Ground Beetle

Barred Owl

Greenbrier

Red-winged Blackbird H

Patent-leather Beetle

Great Horned Owl

Spicebush

Common Yellowthroat H

Rabid Wolf Spider

Raccoon

Eastern Redcedar

Eastern Phoebe H

Eastern Tent Caterpillar Moth

Black Rat Snake

Sassafras

Wood Thrush H

Smooth Crabgrass

Eastern Gray Squirrel

Cinnamon Fern

American Goldfinch H

Common Ragweed

Carolina Chickadee H

Switchgrass

European Starling Mu

North American Millipede

Red-winged Blackbird Mu

Garden Centipede

Common Grackle Mu

Chinese Mantid

Fiery Searcher

European Gypsy Moth

Black and Yellow Argiope

Green Stinkbug

Harvestman

Green Lacewing

Spined Micrathena

Six-spotted Tiger Beetle

Relationship to Humans:

Brown-headed Cowbirds help people by eating pesky insects and eating seeds of weeds so that they don't spread in gardens and lawns. They can cause problems when they are in large flocks and eat seeds of farm crops. Some bird-lovers don't like them because of the problems they cause for other birds.

SCIENTIFIC CLASSIFICATION

KINGDOM
Animal
PHYLUM
Chordate
CLASS
Bird
ORDER
Passeriformes
FAMILY
Icteridae
GENUS
Molothrus
SPECIES
Molothrus ater

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