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At about this point in the fall a few years back, I noticed a curious phenomenon as I drove along Florida Avenue on the U of I campus. Dozens of crows—a “murder” if you will—were returning day after day to a row of majestic trees, for what looked to me like a great big crow party.This wasn’t a roost, where crows gather at night for safety in numbers (and create misery for the unfortunate humans who live below.) It was a raucous, daytime affair, with lots of loud calling and hopping and flapping from branch to branch. [Photos by author: Row of pecan trees stretching south from Florida Avenue toward the round barn on St. Mary's Road; crow with pecan.]
What was the attraction of those trees? I stopped one morning to investigate. On the ground below the crow party were scattered the husks and shells of pecans, a nut I didn’t even know grew in Illinois.So that little mystery was solved, and now I watch each November for the crows to congregate and feast on the pecans as they mature. (As a bonus, I now also know of a place where I can pick up one of my favorite foods from the ground.)
As I had spent time figuring out what crows were up to, I had inadvertently joined what turns out to be a very large and cosmopolitan group—people who are curious about crows.
If you’ve seen the episode of the PBS series, “Nature,” called “A Murder of Crows,” you know that scientific research on crows is illuminating new aspects of their intelligence and sociability on an ongoing basis.
For example, one group featured in the show, from the University of Washington at Seattle, designed a study to ascertain whether adult crows pass along specific knowledge about the world to their offspring.
The scientists knew from earlier work that crows recognize and remember masks worn by researchers who catch them, and that the crows’ dislike for people wearing those masks is communicated among adult birds. The question was whether such knowledge would be passed on from one generation to the next.
It was. A young crow that had learned from its parents to associate a particular mask with danger picked out a person wearing the same mask months later, in an entirely different setting, and gave the same alarm call.
Another area of research featured in “A Murder of Crows” is tool use among crows of New Caledonia, which appear to be the smartest of crows worldwide.
In the experiment, a New Caledonian crow is presented with a piece of food in a narrow box, which it can obtain only by reaching in with a long stick. But the long stick is inside a cage. To retrieve it, the crow has to reach in with a smaller stick, which is suspended from a nearby branch on a piece of string. In essence, it has to think up a three-step plan to achieve its goal.
You can almost hear the wheels turn as you watch the crow contemplate its options and then spring into action.
New Caledonian crows are also famous for the fact that they modify the tools available to them. In an earlier experiment, which you can view online, a New Caledonian crow named Betty crafts a hook from a straight piece of wire in order to pull food from an upright cylinder.
I don’t know whether the American crows we see in Illinois are as smart as all that. But having a better sense of what’s going on in their heads sure makes me want to watch them more closely in the future.
