Imagine you’ve just had a baby and you go off to run some errands. When you come home, you find that, actually, you’ve had twins. You’re sure that you didn’t have twins before, but maybe you miscounted. This new baby looks a little different, but all babies look about the same. Plus, it’s a baby. It won’t take care of it itself. You take on the new responsibility without complaint.
The little tots start to grow up, with the additional child more aggressively demanding food and care than what you’re sure is the original. You have a hard time feeding both this mystery kid and your own, so the child you know is your own starts to get a bit neglected. It’s not your fault – babies need help!
Eventually the child grows up and it looks nothing like you. You’ve started to care for the little tyke and it’s basically family, so you feed him until he’s all ready to go off to college. And you promptly never hear from him again.
This is what life may be like for many bird parents who have unfortunately had their nests visited by a Brown-headed Cowbird. Some birds are able to figure out the ruse and will reject cowbird eggs on sight, but most just roll with the punches and raise the forcibly adopted bird as its own. Others will simply give up on parenting altogether if they found a cowbird egg, abandoning even their own young because cowbirds suck.
There are more consequences for the host parents than simply needing to feed more birds. As I described above, cowbird nestlings are aggressive eaters and are louder and more vocal than most nestlings who belong. In some species, this can alert predators and get everyone in the nest killed, including the cowbird baby.
Occasionally, the cowbird parents will monitor their young, but have no involvement in their rearing. If they notice the cowbird egg was rejected, this upsets them and they will trash the host nest. This vengeance behavior seems to apply consequences for the host bird, who may actually consider that an angry cowbird will visit and destroy the entire nest.
Now, you may be wondering how exactly a cowbird knows to be a cowbird when it’s been raised entirely by a different species. Shouldn’t a cowbird raised by sparrows act like a sparrow? It seems that the brain of a young cowbird is programmed innately to listen for cowbird songs and then imprint on them. If it doesn’t hear another cowbird by a certain time, the young bird will instead continue to live among whatever raised it.
Cowbirds are generally considered pest birds, but they really aren’t pests to anyone except other birds. I’ve not noticed cowbirds being more aggressive than other species at my feeders. They’re certainly less mean than grackles, less messy and voracious than starlings, and not bullies like Blue Jays are reported to be. They may show up in groups, sometimes with other similar birds such as grackles. I’ve seldom seen a cowbird show up without a grackle or Red-winged Blackbird in tow.
The Brown-headed Cowbird will visit your birdfeeders, though they also eat insects. You may get more of them visiting if you provide mealworms. I don’t see cowbirds eating at feeders they can’t easily perch on, so a caged squirrel-proof feeder may help deter them. Their favorite feeder is my tray feeder, because it most closely resembles their preferred place to feed, which is the ground.
As I said before, the Brown-headed Cowbird likes to travel in groups with other similar-looking birds, so at a distance they may be hard to spot and differentiate. They are smaller that grackles, about the size of a robin, and can be spotted by their brown heads over all-black bodies. Are they pretty? Maybe not in a colorful sense, but there is something beautiful about their black and brown.
I suppose it’s up to you if the Brown-headed Cowbird is a welcome visitor at your feeders. I’ve never had issues with them in a purely bird feeding sense, but their brood parasitism is understandably troubling.
How do you feel about the Brown-headed Cowbird? Let me know in a note below!
Side note: I apologize for this post being a few days late. I’ve been so swamped lately.