Thursday, March 17, 2011

Red-tailed hawk seen on U of I campus subject of O'Hare study

Red-tailed hawk seen on U of I campus subject of O'Hare study

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Back on the morning of January 21st, I was dutifully pecking away at my keyboard when I got a phone call from a coworker one floor below. “Quick,” she gasped, “look outside, there’s a huge bird!” I was at the window in a flash, and there, perched atop the nearest streetlight, was a first-year red-tailed hawk.

Now, a red-tailed hawk is an everyday bird in Illinois, and I wouldn’t mention this one had it not been for something I noticed as I photographed it; it was wearing on its wings great big tags, marked with the number 80.[ Photos: 080 on streetlight on Dorner Drive in January; pursuing grey squirrel in Illini Grove earlier this week.]

Thinking Red-tail number 80 must be involved in a local study, I contacted U of I avian ecologist Mike Ward to get the story, but neither he nor any of his colleagues knew anything about it. A query to birdnotes, the Champaign-Urbana birders listserv, brought a more unexpected answer. Red-tail number 80 was tagged by researchers at O’Hare International Airport in Chicago.

Schedules being what they are, it took some time for me to connect with investigators, but last week I spoke by phone with one of them, Craig Pullins. He is part of a team of biologists and technicians employed by the U.S. Department of Agriculture’s Wildlife Services division and based at O’Hare. In general, the mission of Wildlife Services is to resolve conflicts between people and wildlife. At airports, this means deterring animals from taking up residence or hanging around, because of the dangers they pose to aircraft.

So Pullins and his colleagues manage the airport landscape to make it inhospitable to wildlife, and that greatly reduces there the numbers of larger animals, such as Canada geese, white-tailed deer and coyotes. But what’s poor habitat for one animal is often good for another, and the airport’s expanses of short, well drained grass support healthy populations of small mammals, such as voles, and these, in turn, attract birds of prey.

Since 1992, Wildlife Services has worked to keep down the number of owls, hawks and falcons at O’Hare by trapping and relocating them. And that brings us back to Red-tail number 80. It is part of a study begun by Pullins and company last year to determine how the rate of birds returning to the airport is affected by the distance they are moved from it.

Red-tail number 080 was trapped at O’Hare on September 21, 2010, and was among the birds in the study released 120 miles to the west, just five miles short of the Mississippi River. Other hawks in the study are being moved shorter distances--50, 75 and 100 miles.

Why 080 showed up in Urbana nobody can say for sure, although it is common for red-tails to migrate some ways south during winter. Some red-tails tagged for the study have been reported elsewhere around the state, from downtown Chicago to Springfield, Rockford, Decatur and Albany. Others have shown up further away, from Madison, Wisconsin, to Iowa, Alabama, and even Florida.

Of course, the real question with regard to these birds is not how far away from the airport they go, but whether or not they return. And it will be some time before Pullins and his colleagues learn much about how relocation distance affects rates of return. As of this week, Red-tail number 80 is still on campus. I, for one, would be happy to have it stay.