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…
No comments:
Post a Comment