Wednesday, January 20, 2010

The Cosmopolitan Winters of Corvus brachyrhynchos

Here in Maine, we get thousands of migrants who arrive here every summer and stake out their own tiny territories in seaside cabins or camps in the woods, turning Maine's quaint villages into far-flung suburbs of New York and Boston. And every fall, as the days get darker, they flock back south to console themselves against the cold and the dark with the social opportunities of cities.

As it happens, the common American crow does the same thing.

Around this time of year, all over the country, huge swarms of crows flock across the skies and mob the trees at city parks every afternoon and evening. Here in Portland, they seem to start around the northern end of the Eastern Promenade, then they flock over to Lincoln and Deering Oaks Parks before settling in for the night near the new Mercy Hospital buildings near the Fore River.

A few months ago I started working at Maine Audubon, and I asked the staff naturalist, Eric Hynes, what these crows were doing. He told me that, essentially, they're just socializing. While crows are fairly territorial in the summer, in the winter, when food is scarce and predators are more of a threat, they prefer the company of other crows. Thousands of other crows.

It's not all for fun: "They get together every afternoon and check each other out," said Eric. "They might say, 'hey, that guy looks fat and happy today, we'd better follow him and find out where he's getting his food.' Or, 'that one looks sick and scraggly, stay away from him.'" When it gets dark, they bed down together by the thousands to provide safety in numbers against predators.

Crows have also figured out that they're safer in cities, where their biggest nemesis, the Great Horned Owl, is less likely to venture. As a result, these wintertime social flocks tend to gravitate towards urban areas.

To see them for yourself, head out to your local city park this afternoon around 4 pm and walk towards the noise of a thousand crows cawing.


Benjamin said...

I want to see it so badly TAKE PICTURES PLEASE!!!!

Don said...

I've been wondering about this for years. It's really spectacular, and kind of Hitchcock creepy when you drive by the trees full of thousands of crows. The first time I saw this they were up near the East End School.