Corvid Mobsters—Part 2

I have wondered why it is that hawks allow themselves to be shoved around by a bunch of smaller birds (or the same for a crow being mobbed by songbirds). Sure, it may be outnumbered, but in short order a hawk could easily dispatch an overly aggressive and foolish crow—sending the others fleeing through the trees. I’ve watched a hawk try to ignore the mobbing flock, but subsequently choose to flee, with the crows diving and swooping from behind. The hawk doesn’t seem to be inclined to retaliate. Why not?

A little research told me that even though a hawk could easily kill a crow, the act may require an expenditure of too much energy. Food is not always plentiful for flying carnivores. Crows are agile aerial acrobats, and a hawk would likely have to work hard to catch one. It maybe just ain’t worth the effort, so it vacates the scene. Besides, a hawk is not all that territorial. If it just happens to be sallying through, it has no investment in the area, so it allows itself to be driven off. If the hawk has its own babies to protect, however, it’s a very different story. In this case the crows know it and don’t push their luck. Just a little mobbing noise to warrant their awesome reputation and then move on to easier targets.

This crew of crows that I heard the other evening kept up their raucous chorus for about a half hour, as the scene of the action floated through the woods. It suggested to me that they had themselves a real target and were not just playing or bluffing. In time, they calmed down, and quiet once again reigned in the woods. Then, after a while, I could hear one lone hawk plaintively calling out from the direction of where the mobbing had ended. It sounded weak or defeated. I tried to guess whether it was crying out of pain, or a dented ego, or just sassing back. It was not a happy or triumphant call. I think that crows prevailed on that one.

Corvid Mobsters--Part 1

I recently listened to a horde of crows noisily and persistently squawking, cawing, and bellowing off in the woods. I could not see them to know who or what they were hassling, but it seemed to be a case of what is called “mobbing”: when a group of birds surrounds and attacks a larger predator or threat. I’ve watched a group of songbirds mob a crow that posed a threat to their babies. I’ve watched a band of crows mob a hawk, although I couldn’t figure out quite why the hawk was being targeted.

Maybe that’s what I was hearing the other day: crows mobbing a hawk? (They also mob owls and even raccoons, foxes, and house cats.) After nearly half an hour, the ruckus moved several hundred feet down the hill, toward the creek. This suggested to me that the crows were mobbing a bird that flew that way, rather than a mammal, since they remained in the trees and moved rather quickly. But what was really going on? I don’t think the crows were defending their babies—it’s late enough in the season that all youngsters would be fledged and pretty much on their own by now. Could the youngsters be playing some kind of game among themselves?

Crows tend to hang together in colonies, so when a threat is spied, they can depend on a group to quickly form, to harass and drive off the menace. They have several possible motivations for mobbing a larger bird: They may be defending their nests of eggs or nestlings. They may be protecting their food supply—crows are also predators of songbirds and other small critters. They may be teaching youngsters how to mob. Earlier in the season they may be showing off to potential mates. (“Hey, sweetie, see how brave I am? Want to hook up with me?”) Or maybe they’re just playing. Sometimes crows—especially young ones—will play a game of hide and seek, wherein the “it” crow tries to hide and the others fly about and shout at the hider, once he’s been spotted.

When crows mob, they are either trying to drive away a predator or simply alerting all birds in the vicinity that a pariah has entered the neighborhood. A hawk or owl may simply be passing through and resting on a branch for a few minutes—unaware that it has violated corvid territory. The crows’ frenzy is an ambivalent mixture of fear and aggression—fear for their individual safety and a boldness engendered by the need to appear formidable. If you watch crows mobbing a larger bird, you can see a fascinating dance, wherein each one tries to do it from a safe distance, while seeming to be fierce and intimidating. Like teenage urban boys bluffing, they sound as if they’re calling out, “Hold me back, boys, before I pound his ass into the pavement!”

The objective of mobbing may be to engage the intruder in multiple dive bombings and buzzings, to prevent the larger bird from being able to focus on one target. Keeping him distracted, they swarm around and cause the hawk to leave, just to get a little peace for itself. Or the crows may be attempting to teach a young hawk or owl to give crows a wide berth in the future: If they get one of their band to act as a decoy—causing the hawk to focus forward, as the others attack from behind—the young hawk might conclude that a crow is one of those magical critters that will fly in your face, as it simultaneously pecks at your butt. If that impressionable young hawk spreads the news by telling its buddies what happened, the crows will have achieved a great coup. The crows may even top off the humiliation by defecating on the hawk.

More on mobbing next time…