Saturday, February 15, 2014

Brown-Headed Cowbirds: Nuisance at the Feeders

One day I noticed an odd looking black bird mixing with other birds at the feeders. Taking a closer look, I noticed the black bird had a bluish tint all over except for his head, which was brown.  Soon after, a plain brown bird was next to him, looking for seed.  I was unfamiliar with these type of birds and decided I would do some research on them later.

The following day, there were at least half a dozen of these birds at the feeders.  The next day, there were a couple dozen at the feeders, and they barely allowed enough room or food for the smaller birds.   After some research, I learned these birds are Brown-Headed Cowbirds, also known as parasitic birds.  In other words, the Brown-headed Cowbird is North America’s most common “brood parasite.” A female cowbird makes no nest of her own, but instead lays her eggs in the nests of other bird species, who then raise the young cowbirds. Cowbirds are not monogamous. Studies show that males and females have several different mates within a single season.  Some birds can recognize cowbird eggs but are too small to get the eggs out of their nests. Instead, they build a new nest over the top of the old one and hope cowbirds don’t come back. Some larger species puncture or grab cowbird eggs and throw them out of the nest. But the majority of hosts don’t recognize cowbird eggs at all.  Cowbird eggs hatch faster than other species eggs, giving cowbird nestlings a head start in getting food from the parents. Young cowbirds also develop at a faster pace than their nest mates, and they sometimes toss out eggs and young nestlings or smother them in the bottom of the nest.  In winter, Brown-Headed Cowbirds may join huge roosts with several blackbird species. One such mixed roost in Kentucky contained more than five million birds. (Information from

Certainly I would rather not have these pesky birds around, but I haven't figured out yet how to provide food for the other birds without inviting cowbirds.  Ryan's solution- "you want me to shoot em for ya?"...Ummmm, no Ryan, that won't be necessary but thank you for offering some assistance.  I'm going to observe the bird activity in our front yard a few more days and see if further steps are necessary. Hopefully they will find an easy food source somewhere else.

The mostly brown birds in the photos are female cowbirds.  Male Brown-Headed Cowbirds have glossy black plumage and a rich brown head that often looks black in poor lighting or at distance. Female Brown-Headed Cowbirds are plain brown birds, lightest on the head and underparts, with fine streaking on the belly and a dark eye.

Brown-Headed Cowbirds feed on the ground in mixed-species groups of blackbirds and starlings. Males gather on lawns to strut and display for mates. Females prowl woodlands and edges in search of nests. Brown-Headed Cowbirds are noisy, making a multitude of clicks, whistles and chatter-like calls in addition to a flowing, gurgling song.

Video of female cowbird captured from my bedroom window:

Video of male/female courtship (not mine):

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