CROWS: Roosting

Right now, through the winter, it’s the season for crows to gather together at night to roost. I’m Jim Metzner, and this is Pulse of the Planet, presented by the American Museum of Natural History.

We’re listening to the sound of crows mobbing one of their most feared predators: the Great Horned Owl. Although the crows can’t kill the owl, they can drive it away from where they’re roosting. There’s safety in numbers, but there may be other reasons why crows flock together.

“The reasons why crows roost in these large numbers are… aren’t completely worked out yet. But we have a couple of good ideas.”

Professor Kevin McGowan is Associate Curator of birds and mammals at Cornell University.

“It is protection from predators by being in large numbers. By being in these huge groups you may overwhelm any predators that might try to take crows. And there are some, Great Horned Owls being the most notable.”

Crows often roost in large numbers. 40,000 or more can gather where food and shelter are available: on a farm or even around a dumpster in a mall parking lot. In Nebraska and Oklahoma roosts have been documented as having up to one million individual crows.

“There’s another idea that they get into these roosts as a place to exchange information. And that is, if you haven’t been too successful foraging that day, you go to the roost and you sit and watch for the guys that look like they’re fat and happy coming in looking well fed and then you keep your eye on them and follow them out in the morning cause they’ll probably be going out to the same place where they were successful. So, an idea of information transfer there. There’s also the possibility that there are social interactions that go on in these groups that are important for these birds to figure out where their place is in society. How good a competitor they look like they’re going to be. To practice their fighting or social skills as well.”

We’ll hear more on crows in future programs. Pulse of the Planet is presented by the American Museum of Natural History. I’m Jim Metzner.

CROWS: Roosting

Protection from predators and communication are a couple of reasons why crows are roosting en masse this month.
Air Date:11/11/1997
Scientist:
Transcript:

Right now, through the winter, it's the season for crows to gather together at night to roost. I'm Jim Metzner, and this is Pulse of the Planet, presented by the American Museum of Natural History.

We're listening to the sound of crows mobbing one of their most feared predators: the Great Horned Owl. Although the crows can't kill the owl, they can drive it away from where they're roosting. There's safety in numbers, but there may be other reasons why crows flock together.

"The reasons why crows roost in these large numbers are... aren't completely worked out yet. But we have a couple of good ideas."

Professor Kevin McGowan is Associate Curator of birds and mammals at Cornell University.

"It is protection from predators by being in large numbers. By being in these huge groups you may overwhelm any predators that might try to take crows. And there are some, Great Horned Owls being the most notable."

Crows often roost in large numbers. 40,000 or more can gather where food and shelter are available: on a farm or even around a dumpster in a mall parking lot. In Nebraska and Oklahoma roosts have been documented as having up to one million individual crows.

"There's another idea that they get into these roosts as a place to exchange information. And that is, if you haven't been too successful foraging that day, you go to the roost and you sit and watch for the guys that look like they're fat and happy coming in looking well fed and then you keep your eye on them and follow them out in the morning cause they'll probably be going out to the same place where they were successful. So, an idea of information transfer there. There's also the possibility that there are social interactions that go on in these groups that are important for these birds to figure out where their place is in society. How good a competitor they look like they're going to be. To practice their fighting or social skills as well."

We'll hear more on crows in future programs. Pulse of the Planet is presented by the American Museum of Natural History. I'm Jim Metzner.