A few weeks ago, one of my officemates and I were discussing how dangerous it is to be a baby bird when he mentioned that among the creatures that will eat young birds—rodents, deer, ants, slugs—are Western Scrub Jays. “I’ve seen them hunt down and eat young fledglings,” he said. So when, this weekend, I saw a scrub jay pecking at something small and cheeping, I dropped my grocery bags and ran.
The victim was a young fledgling, probably no more than a day or two out of the nest. He cowered on the ground when I reached him. I looked around for his parents, but although there were many spectators peering down from the branches—European Starlings, Chestnut-backed Chickadees, Bushtits—none of them seemed upset. They were there to watch a show, not defend a baby. And although I wasn’t sure what species the fledgling was, I could tell he was too big to be a chickadee or a Bushtit, and he lacked the long-faced look of young starlings.
Scrub jays are smart birds, and I knew if I left the fledgling there, he would go right back on the menu. Too, from the way he huddled and didn’t move, I worried that he was injured. I took him home.
Rescued fledgling
Away from the attentions of the jay, he quickly perked up. He looked a little bruised around the face but seemed otherwise healthy, alert, able to perch and even flutter short distances. When I took him to the local wildlife rehabilitators they said he looked good. He joined their several other fledgling wards to recuperate. There, he will learn to be an adult bird and eventually be released.
Sleeping. He hadn’t quite figured out the tuck-head-under-wing trick yet.
Note his just-growing in tail feathers, still partially in their white sheaths.
So the story has a happy ending! Well, except for the scrub jay, who probably intended to feed the fledgling to her own hungry chicks.
Except… there’s another version of the story. See, before I turned the fledgling (who I called Zed) over the rehabilitators, I wanted to know what species he was, because some wildlife rehabilitators won’t accept invasive species (European Starlings, House Sparrows, pigeons). So I did some internet searching. Zed, it turns out, is a Brown-headed Cowbird.
What Zed will look like when he grows up, if he is indeed a “he.”
Photo by M. LaBarbera
What he will look like if he is actually a she.
Photo by M. LaBarbera
So here’s another version of Zed’s story:
His mother watched the birds around her, noting where they put their nests and when they started laying. When they were away, she quickly darted in to the nest, laid her own egg among theirs, and left. Some of the time, this worked: birds are under strong pressure to accept any eggs that are in their nest, because the cost of rejecting their own eggs by accident would be terrible, and the eggs that are in their nest are their own eggs – most of the time.
Zed developed quickly in his egg, racing to beat his foster siblings. He probably hatched first, giving him an advantage in getting food from his foster parents. He got more food than any of his nestmates, and grew faster and bigger than them. Some of them may have starved because of him. Even if they all lived, they certainly got less food and were less healthy than they would have been without him.
Cowbird nestling (left) with Wood Thrush foster mom and her chicks.
Photo by Kelly Colgan Azar
Then one day, Zed’s large size and his loud begging call caught the attention of a scrub jay, and he was almost lunch. Instead, he was picked up by me, and now he continues to receive parental care from a species that isn’t his own: humans.
What species cared for him before the scrub jay found him? I don’t know. Any of those spectator birds could have been his foster parents—although their lack of distress at his peril still makes me doubt it. But the most likely thing, based on what cowbirds seem to do in that area, is that he was in a junco nest. Zed probably took food from the bills of baby juncos.
Cowbird fledgling (older than Zed) begging from its junco foster parent.
Photo by Flavio M. Rose
It’s hard not to be a bit upset about this. Brown-headed Cowbirds are cheaters, lazy and destructive to all the hard workers around them; they’re the grasshopper in the tale of the grasshopper and the ant, if the grasshopper had stolen all the ant’s hard-earned food for itself and survived the winter while the ant starved. They leave their babies in the nests of strangers without a backward glance; they cause the nestlings of their host species to starve; their strategy isn’t even sustainable, since if they succeeded too often, their host species would go extinct and they would have no one to raise their babies for them. The technical term for what they do is “nest parasite,” and there’s a reason it’s an ugly term.
Cowbird fledgling being fed by its Common Yellowthroat foster parent.
Photo by Dave Maher
But… can you blame a species for existing? Their strategy works. They work hard at it, in their own evil way: they have to find many, many nests at the right time, and they have to lay many eggs, since the success rate isn’t great. Nest parasites have a lot of neat adaptations that I’ll write about in the future (because this is already a long post!). One of the big ornithological mysteries used to be how nest parasites know what species they are, since they may never see another of their species growing up. They work hard at being lazy.
And you can’t really blame any individual cowbird for being a cowbird. It’s not Zed’s fault that, at a species level, he’s a jerk. He’s just a hungry baby bird.
Besides, how could you resist this face:
Tough Little Birds 
As always, great post. You have a good sense of narrative too.
Amused by the creeping judgmental language for the cowbird as your piece developed. In evolution, nothing is evil and nothing is too evil. In Europe the cuckoo expels the other nestlings and it is they who feed the corvids.
The cuckoos are definitely “worse” than the cowbirds – the cowbirds passively harm their foster siblings, but some cuckoos simply shove the other eggs out of the nest, or attack their foster siblings with a specially sharp nestling bill.
I think it’s interesting that people seem generally more bothered by nest parasites than by, say, predators. Both cause harm to other creatures, but I think we have this idea that the predators HAVE to kill while the nest parasites are just being lazy; plus there’s the disturbing aspect of “good” intentions (inclination toward parental care) used against the unsuspecting foster parents. A hawk will just kill you; a cowbird will use your own instincts to manipulate you into killing your babies.
Nice twist! I didn’t see that coming at all. I’ve heard about cowbirds – and I’ve wondered what the adults do all year while other poor birds are busy raising their babies for them. Party time! Maybe the moral of the story is that nature is not always cute and fluffy and it doesn’t play by our rules. But then, we don’t even follow our own rules, so who are we to talk?
Very enjoyable post!
There certainly are some different kinds of creatures. Interesting post.
Great story, and along the lines with your research on Juncos. Might be interesting to know how many Juncos bring up fledglings of other species.
This is such a cute story, and I love the pictures of Zed. I had no idea that cowbirds nested that way!
There’s another side to the story. The side where the Cowbirds evolved this “evil” strategy because they were dependent on American Bison for their food, eating the insects that they stirred up as well as picking parasites out of their wool. Bison are migratory and never stopped traveling to new pastures so of course there was no way for the Cowbird to raise it’s own young, if they hadn’t parasitized other nests they would have died out, or at least been forced to work much harder for less profit.
Its unnecessary now because the Bison are gone from the range, and the livestock stay in one place pretty much year round. Right after this change was made the Cowbird population exploded from the overabundance of food and lack of effort required to obtain it. So in other words humans made the Cowbird “evil”, a millennia of necessity driven behavior isn’t going to change when it’s still the easiest way, even if the necessity is now gone.
Does anyone know what fledgling juncos eat, past the “baby” stage, when they are getting
their wings and no longer have the yellow marker on their beak indicating “baby”?
Juvenile juncos eat mostly bugs, although as they get older they’ll gradually start eating more seeds. Mostly bugs, though – they’re easy to digest.
If you’re asking because you’re caring for a young junco, I strongly urge you to contact a licensed wildlife rehabilitator. They have expertise that will dramatically increase a young bird’s chances of survival. Young birds can be very fragile and require a knowledgeable caretaker.
Since the scrub jay was attacking Zed I was thinking how do you tell the scrub jay is trying to eat a bird?
There are a few reasons a bird might attack another bird. They might both be in competition for a resource (food, territory, mate), or one might be attempting to eat the other. You can distinguish these based on who the participants are: two male songbirds fighting, for example, will be fighting over resources. A Peregrine Falcon attacking a dove will be aiming to eat it. In this case, I know that scrub jays will eat other birds when they can, and I know that a baby bird won’t be competing with the jay for resources; so I can conclude that the jay has lunch on his mind.