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November 30, 2001

Campus crows persevere in creative turf battle

crows sitting in a tree
Campus crews have been trying for years to discourage migrating crows from "wintering" in campus trees. Several options work temporarily; none have proven to be a long-term solution. Photo by Bob Elbert.
by Diana Pounds
Every fall, they mass on campus in Hitchcockian proportions 10,000 to 12,000 crows, swooping down from the north in big black clouds to make Iowa State their winter home.

And every fall, ISU facilities staff try to frighten them away. Over the years, the humans have tried a number of scare tactics. They've flashed strobe lights, floated big-eyed balloons, and piped bird-in-distress calls. They've gone low tech walking the campus, slapping boards. And high tech blow-up scarecrows that periodically self-inflate and wave their arms. They've even dabbled in the macabre hanging a dead crow from a branch.

The problem is, crows are a pretty unflappable bunch.

"They get used to about anything you do," said Dave Miller, ISU facilities and utilities director. Distress calls, balloons, inflatable scarecrows (the staples of ISU's crow arsenal) work for a few days, but eventually, the crows simply ignore them.

ISU's response has been a crow harassment campaign that involves frequently moving crow controls from place to place. The idea is to prevent crows from taking up permanent residence anywhere and building up an extraordinary amount of bird droppings, Miller said.

Not only are droppings an unpleasant mess, they may carry disease. Safety experts say the biggest health risk occurs when workers try to sweep up dry droppings, creating airborne dust, Miller said. "That's why we don't try to remove the droppings unless we have wet, windless weather."

ISU animal ecologist Jim Pease says crow problems are common in Iowa. "I've gotten calls from cities all over the state.

"Crows are smart," he added. "They've learned that cities have lots of big trees for roosting and buildings that block wind and give off heat. It can be as much as 10 degrees warmer in the city than the country on a cold winter night."

Crows have adapted to city life, learning to peck through garbage bags for food, Pease said. They also feed off farm fields and road kill and, during the day, may travel 10 to 15 miles from roost sites to eat.

"Around 3:30 or 4 p.m., they start streaming back towards the city for the evening," Pease said.

ISU staff have discussed the campus crow problem with Pease and a variety of other experts on- and off-campus over the years. "Most say it's not likely that we can eliminate or substantially affect the presence of crows on campus," Miller said.

One option ISU staff have not seriously considered is killing the crows. There are crow hunting seasons. However, it's illegal to shoot within city limits.

While some cities have made exemptions to shooting regulations, Miller says he doesn't view shooting the crows as a viable option.

"With a population of 10,000 crows, you would have to kill a very large number of birds, and that would upset a lot of people.

"Current crow-control techniques are working somewhat," Miller added. "But we're always open to trying something new."

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