The Brown-Headed Cowbird

Written By: William McReynolds - Highlands Plateau Audubon Society | Issue: 2019/08 - August

This bird is plentiful and wide ranging, native to the U.S. Look for it year round in the northeastern U.S. across the continent to the southwest, including Western North Carolina. Some migrate between Canada and Mexico. They were abundant on the Great Plains over a century ago, congregating around the great herds of bison that roamed the continent, breaking up the soil with their hooves and exposing beetles and other insects, spiders, grubs and worms.

The Brown-headed Cowbird (Molothrus ater) is close kin to other large blackbirds such as grackles and Red-winged Blackbirds. Its favorite habitat is open country, fields and farms, and forest edges. They feed at ground level, mostly insects and seeds, and will follow grazing animals, foraging in the upturned soil. They will come to bird feeders to eat seeds with their finch-like beaks.

Male Brown-headed Cowbirds are very vocal. Their throaty song has been described as “squeaky gurgles” along with various whistles and chatter. It’s distinctive, calling to mind the gargled song of the Common Grackle and Red-shouldered Blackbird. Males can have shouting matches: gurgle, gurgle, whistle, chatter, chatter, chatter. Males and females sing duets, him repeatedly gurgling and squeaking loudly and her coming in chattering repeatedly right on cue.

He courts her in fine Lothario fashion – fluffing his body feathers, lowering and spreading his wings and bowing deeply while singing enthusiastically, a courtesan’s beau geste. Careful avian research has shown that she usually goes for the suitor that sings the most. Subsequent pair bonds are strong and monogamous. She might lay over 30 eggs in a season.

There is no nest. Cowbirds are notorious brood parasites. They lay their eggs in other birds’ nests, over 100 host species, meaning that cowbird fledglings are incubated, fed and protected by host parents. That raises the question of how cowbirds come to congregate with their own kind, forming small and large flocks or “Followings.” The answer is found in their distinct vocalizations that fledging cowbirds instinctively recognize and imprint upon. Mother Nature is wondrous in her inventiveness.

Happy birding from the Highlands Plateau Audubon Society.

The mission of the Highlands Plateau Audubon Society is to provide opportunities to enjoy and learn about birds and other wildlife and to promote conservation and restoration of the habitats that support them. HPAS is a 501 (c)(3) organization, a chapter of the National Audubon Society. Visit highlandsaudubonsociety.org for information on membership and all activities.