Brown-headed cowbird
The Brown-headed Cowbird is a species of bird recognized for its distinctive brown head and its behavior of following grazing cattle to feed on insects stirred up from the grass. These birds belong to the family Icteridae, which includes various American blackbirds, and are typically found in North, Central, and South America. Female cowbirds exhibit a unique reproductive strategy known as brood parasitism, wherein they lay their eggs in the nests of other bird species, often displacing the host's eggs in the process. This behavior can threaten the reproductive success of the host species, as cowbird chicks often outcompete the host chicks for food and space.
Brown-headed Cowbirds measure six to eight inches in length and have a wingspan of about one foot. Their diet varies with the seasons, shifting from insects in warmer months to seeds and fruits during autumn and winter. Social and flock-oriented, cowbirds can be seen in open fields and woodlands, often mixed with other bird species. Despite concerns about their impact on other birds, Brown-headed Cowbirds maintain a stable population and are classified as a species of least concern in conservation status. Their melodious calls and whistles contribute to the diverse sounds of their habitats.
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Brown-headed cowbird
Brown-headed cowbirds receive their name from their brown heads and because they often feed on insects that grazing cattle stir from the grass. Female cowbirds have a habit of laying their eggs in other birds' nests so that the other birds incubate the eggs and raise the cowbird young. Sometimes cowbirds will even throw out the other birds' eggs.
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Icteridae
Genus: Molothrus
Species: Ater
Brown-headed cowbirds belong in the family of birds called American blackbirds. The family contains 108 species of birds with black bodies which live in North, Central, and South America. Each species has distinguishing features on their bodies, which are otherwise all black. Female brown-headed cowbirds have brownish-gray heads and bodies. Brown-headed cowbirds are six to eight inches (fifteen to twenty centimeters) long and weigh one to two ounces (twenty-eight to fifty-six grams). Their wingspans are around one foot (thirty centimeters).
These birds are called cowbirds because they typically feed near grazing cattle. As the cows stir up insects from the grass the cowbirds are nearby to snatch up the insects. They also pick seeds from the cattle's manure. These birds have been called buffalo birds because they used to follow herds of bison on the plains. During warmer months of the year, the cowbirds do not rely on cattle to find food. They are able to find grasshoppers, beetles, flies, and caterpillars on their own. Autumn and winter change the birds' diets to seeds and certain fruits.
Throughout the year, except when they are mating, the cowbirds are social and live in flocks in the open country and woodlands of North America. These flocks may be a mix of starlings, red-winged blackbirds, and grackles. The cowbirds may seem friendly to the other birds, but they are actually a threat to other bird species because they are brood parasites. In general, a parasite is a plant or animal which lives inside or on another animal, called a host, and takes advantage of the host, or does not benefit the host. Brood parasites are birds which lay their eggs in the nests of other bird species so that the other birds incubate the eggs and raise the young. The brood parasites do not have to do any work to raise their young. This is a threat to other birds because some of them do not know how to throw out or get rid of the cowbirds' eggs. Some birds do move cowbird eggs from their nests or bury them beneath a nest lining so that they do not incubate and hatch. Not only do cowbirds lay their eggs in the nests, but they may even throw out eggs of the hosts to make room for their own. This reduces the number of other birds which hatch and become adults.
Brown-headed cowbirds form pairs in April and May in order to mate. The females then look for the nests of other birds in which to lay their eggs. They may lay their eggs in the nests of as many as seventy-five different species. Each female may lay up to thirty eggs in one season, usually one egg per nest of a host. Each white or bluish, lightly-brown-speckled egg hatches after only ten days, which is often earlier than the eggs of the host species. Since they hatch before the hosts' chicks, the cowbirds get all the food the hosts bring to the nests. They grow quickly and usually starve the other chicks or crowd them from the nests. Not only are the cowbird chicks larger than many of their hosts' chicks, but they may grow larger than their adult hosts as well. By the time they are two weeks old, the cowbirds can feed themselves, fly, and join a flock to migrate south. They are able to mate the next spring.
The cowbird song sounds like bubbly whistles, while its calls are high-pitched clucks and whistles.
Brown-headed cowbirds can live up to sixteen years in the wild. Due to the vast number of eggs they can lay and how many young survive, the species is of least concern in conservation status.
Bibliography
“Brown-Headed Cowbird.” Audubon, 2024, www.audubon.org/field-guide/bird/brown-headed-cowbird. Accessed 11 Apr. 2024.
“Brown-Headed Cowbird Overview.” Cornell Lab of Ornithology, 2024, www.allaboutbirds.org/guide/Brown-headed‗Cowbird/overview. Accessed 11 Apr. 2024.
Coetzee, Chanel. “Brown Headed Cowbird.” A-Z Animals, 7 Oct. 2022, a-z-animals.com/animals/brown-headed-cowbird/. Accessed 11 Apr. 2024.