Molothrus Ater – Brown-headed Cowbird

Molothrus Ater - Brown-headed Cowbird found in the US

Small obligate brood parasite icterid from temperate and subtropical North America. Northern birds migrate to the southern United States and Mexico during the winter, returning to their summer home around March or April.

Quick Overview: Molothrus Ater – Brown-headed Cowbird
Body size: Around 7-8.25 in (18-21 cm) and a weight of 48 g (1.7 oz)
Main colors: Gray, Brown
Range: Throughout the United States
Migratory Bird: Yes
Best time of the year to see in the U.S.: All Year (January – December)
Conservation Status: Least Concern

Brown-headed Cowbird Description

They have a pointed gray beak and a drab brown body with bright colored stripes. They are distinguished by beak morphology and wing chord. Men with a conical beak and an upper mandible profoundly bent have a wing chord, men with a straight upper mandible and a wing chord larger than males. Female had straight upper mandibles with wing chords while having straight upper mandibles with wing chords less than 9.1 cm.

Molothrus Ater - Brown-headed Cowbird found in the US
Molothrus Ater – Brown-headed Cowbird. Photo by: Christopher Paquette

Size

These birds have a length of 7-8.25 in (18-21 cm) and a weight of 48 g (1.7 oz). Their wings could range from 11.75-13.75 in (30-35 cm).

Feeding

Brown-headed cowbirds search for food on the ground in grasslands. Insects from the grass are often stirred up by herds of animals, such as cows. Plants, including fruits and seeds, make up 75% of their diet. They eat spiders and arthropods like grasshoppers and leafhoppers. This helps females produce eggs by increasing calcium levels in their bodies. Females consume eggs to get additional calcium, but men do too. During the winter, they eat mostly grains.

Habitat

This species’ habitat includes woodland margins, riparian zones, dense thickets, grasslands, fields, and cattail marshes. They seek ecotonal environments near host nests and feeding places. Brown-headed cowbirds are seen near woodland borders early in the morning. Afternoons are spent foraging in open areas like prairies.

Behavior

Brown-headed cowbirds are sociable at night but alone by day. Mating happens at this period, usually in the pair’s home area, away from other birds. Morning lone females search for host nests. Brown-headed cowbirds feed in groups in the late afternoon. During the winter, they flock with other icterids and European starlings. Roosting populations can reach 38 million. The amount of displacements, song spreads, and flight whistles in a male’s repertoire establishes social order.

Molothrus Ater Scientific Classification

  • Kingdom: Animalia
  • Phylum: Chordata
  • Subphylum: Chelicerata
  • Class: Aves
  • Order: Passeriformes
  • Family: Icteridae
  • Genus: Molothrus
  • Species: Molothrus ater

Best time of the year to see

In the United States, the best time of year to see these birds is all year round, regardless of the season. This refers to any month of the year between January and December.

Distribution of the Brown-headed Cowbird in the USA

Breeds throughout a large section of Canada, from southern Yukon and the Northwest Territories to the southeastern United States. Winters in the middle and southern regions of its breeding range, which stretches from the Pacific Coast to the southwest, the Ohio River Valley, and southern New England, all the way to Mexico.

The Brown-headed Cowbird can be found in the following states in the United States – Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin and Wyoming.

Molothrus Ater – Brown-headed Cowbird

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