Brown-headed Cowbird

The Brown-headed Cowbird is a small brood parasitic icterid of temperate to subtropical North America. They are permanent residents in the southern parts of their range; northern birds migrate to the southern United States and Mexico in winter, returning to their summer habitat around March or April.

The brown-headed cowbird is typical for an icterid in general shape, but is distinguished by a finch-like head and beak and is smaller than most icterids. The adult male is iridescent black in color with a brown head. The adult female is slightly smaller and is dull grey with a pale throat and very fine streaking on the underparts.

Special mention about the Brown-headed Cowbird is a brood parasite: it lays its eggs in the nests of other small passerines (perching birds), particularly those that build cup-like nests. The brown-headed cowbird eggs have been documented in nests of at least 220 host species, including hummingbirds and raptors. The young cowbird is fed by the host parents at the expense of their own young. Brown-headed cowbird females can lay 36 eggs in a season. More than 140 different species of birds are known to have raised young cowbirds.


Photo Gallery


Text and photographs © HJ Ruiz – Avian101

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19 thoughts on “Brown-headed Cowbird

  1. how very fascinating this post is, HJ. what passes my mind is how fledgling cowbirds end up learning how to be, well, cowbirds. IOW, right now our young Robins are being shown by their Robin parents how to listen for and go after underground worms. I watch this from my deck. They aren’t being shown by a Goldfinch surrogate parent how to eat sunflower seeds, thank heaven, for they’d die. Baby birds learn the ropes of finding food from their own kind. Or at least that’s what I’d always assumed was so…and logically so, at that.

    • Let me tell you that sometimes birds do a better job rearing their brood than humans! Read my post tomorrow about this topic. Thanks Lance! 🙂

  2. In addition to visiting the nests where she lays her eggs to make sure they’re being taken care of, usually at the expense of the host bird’s own offspring, maybe the female cowbird is also imparting some tips on how-to-be-a-cowbird-when-you-grow-up. But more likely this is genetic information that has been ingrained for millennia, and young cowbirds know how to immediately recognize other cowbirds when it’s time to organize in feeding flocks. I often see cowbirds with other blackbirds in summer and early fall. It’s hard not to be ambivalent about them, because they are beautiful and compared to all the other threats that confront their host species, we may be overreacting to the cowbirds’ impact upon them. Great photos!

    • Nature has all the genetic info figured out, I read about a study to decrease the number of cowbirds with a controlled laying of eggs etc. The result was that instead of decrease, the count went up by a high percentage. These birds control the number of times they lay eggs in a year. It’s an amazing event.
      Thanks Lisa! 🙂

  3. Wow! That’s quite fascinating. They have a nanny to take care of their kids from before birth. I heard that an osprey nest just north of us had 8 eggs, and I know they only lay 2-4…so maybe they were cowbird eggs? But only two chicks hatched, both ospreys.

  4. Thanks again for another very interesting post and lovely set of images about a bird I do not have here. I am learning a great deal from my lovely blogger folk like you. 🙂

  5. My birding friend told me the last time she was at the preserve she actually witnessed a cowbird laying an egg in a Baltimore oriole nest! That was also a very interesting discussion above, about how do cowbirds learn to be cowbirds from their surrogate parents, as I had never even thought of that!! Very interesting, indeed! 🙂

    • Birds never cease to amaze me, they have a short life but the great part of their skills are not acquired by experience instead are embedded genetically. Thanks Amy! 🙂

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