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Friday, November 12, 2010
100 to 1
The other day, as I was tallying American crows at Nature Boardwalk (all the birds at Nature Boardwalk are counted each weekday) my count was suddenly and dramatically disrupted. The crows started frantically flying off in all directions, making quite a ruckus.
What was going on? At first, I had no idea what all the fuss was about. After a few minutes, the flock (also known as a “murder”) of approximately 100 crows settled back down on the patch of grass they had previously occupied, and I resumed my count. Then, to my surprise, the whole incident repeated itself!
This time, on closer inspection, I figured out the source of the commotion. The Nature Boardwalk’s resident Cooper’s hawk was swooping down and scaring off the crows, scattering them every which way. It would single out a crow and chase it aggressively until tiring of the pursuit. After all the crows were riled up, the hawk would perch in a tree overhead and survey the chaos it had created.
What was the hawk’s motive? I can’t know for sure, but what happened next hinted at a possible rationale. A few crows came over to the perch where the hawk was sitting and began swooping in, diving at the hawk and harassing it. This behavior is known as “mobbing,” and crows are known to mob much larger birds of prey, including hawks. The hawk flew from branch to branch to avoid the pesky attackers, but they were relentless. Finally, the hawk was fed up and it swooped into the flock of crows and dispersed them all again.
I watched this whole progression repeat itself about every five minutes for half an hour. When I left, the two teams didn’t seem any closer to reaching a truce. It would seem 100 crows versus one Cooper’s hawk is a fairly even match. They certainly put on an impressive show!
Nature Boardwalk at Lincoln Park Zoo
By transforming the South Pond into Nature Boardwalk, Lincoln Park Zoo has created an urban ecosystem in the heart of the city. Enjoy a virtual view as native plants and animals establish themselves in this rare refuge.
As Lincoln Park Zoo’s director of horticulture, Brian oversees the zoo’s gardens, from bud to bloom.
As coordinator of wildlife management, Mason chronicles the bugs, birds, fish, insects, mammals and more that make their homes at Nature Boardwalk.
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