Saturday, May 27, 2017

Crows commute 20 miles to work

From The Secret Life of Urban Crows by James Ross Gardner.
There was nothing at first, just an empty sky. Then, a caw. A crow appeared on a nearby power line. Then another caw and another crow. Suddenly crows flew in from all directions. Their plaintive entreaties soon combined into a chorus. New arrivals joined what quickly grew into a cacophonous dervish of black silhouettes swirling directly above Swift.

It was like sorcery. Conjuring dozens of birds from thin air by simply removing fabric from a body.

This, according to Swift, is what its like to attend a crow funeral—an instinctive ritual that evolved generations ago and was just discovered by humans; Swift coauthored an article on her findings in the journal Animal Behaviour in 2015. The gist: Upon spotting one of its dead, the flock attends to the fallen bird en masse with loud shrieking. Given enough time the throng will mob any predator it thinks is responsible, like say, a human in a Dick Cheney mask, or in a mask like the one Swift had in her bag (the lab affectionately refers to that be-soul-patched fellow as Joe).
But what if I were to tell you that the crows you spy in your yard are almost always the same individual crows? That those birds—usually two, a male and a female known as a territorial pair—don’t live there but fly in every day from 20 miles away? During the day urban crows rummage and build nests in a specific spot, in a specific neighborhood, then decamp for the evening to a massive, crowded roost outside the city—their own crow planet— and report back to the neighborhoods each morning. Like you, they commute to work.

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