The Brown-headed Cowbird is Michigan's most controversial songbird. Males are glossy black with a coffee-brown head; females are plain gray-brown. They're famous — or infamous — as brood parasites: females build no nest at all, instead laying up to several dozen eggs per season in the nests of other species, leaving warblers and sparrows to raise oversized cowbird chicks.
Cowbirds followed the bison across the Great Plains historically, feeding on insects stirred up by the herds; agriculture carried them east. Their parasitism is a natural strategy, but it added real pressure to Michigan's endangered Kirtland's Warbler, where cowbird management became part of that bird's recovery story.
Seeds and waste grain dominate, gathered on the ground in fields and feedlots; insects — especially grasshoppers — spike in summer. At feeders they take millet and cracked corn, usually arriving with other blackbirds.
They evolved as nomads following bison herds, never staying anywhere long enough to nest. Laying eggs in other birds' nests let them keep moving — a strategy that persists even though the herds are gone.
No — it's illegal. Cowbirds are native and protected under the Migratory Bird Treaty Act; only permitted management programs (like the one that protected Kirtland's Warbler) may remove them.
Cowbird eggs hatch fast and the chicks grow faster, out-competing the host's own young for food. The host parents' feeding instinct is triggered by the loudest, biggest gape — which is always the cowbird.
The peak falls from May through July, when the population is at its highest. The full window runs from March to November, with birds scarce at both edges.
The youngster is a juvenile cowbird — pale gray-brown, scaly-backed, and often much larger than the warbler, sparrow, or vireo raising it. Cowbirds lay their eggs in other species' nests and never raise their own young.
Other birds you might be looking at instead.
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