Dec. 3, 2009


Photo by Bob Elbert.

Crow countermeasures

by Diana Pounds

If you spend much time on central campus at dusk this time of year, you've probably heard it -- the amplified chatter of a bird echoing from a nearby rooftop. You're hearing a recording of an agitated crow. While the sound may not be unpleasant to you, it bothers crows, often driving them elsewhere. And that's the point.

Distress signal

This recording of crow distress calls is broadcast from ISU rooftops to chase away the birds.

Fall fly-in

Fall marks the beginning of crow season at Iowa State. Crows swoop down from the north to winter in Iowa. They hang out in rural areas during the day, feasting in farm fields, then head to campus for the evening. Iowa State's park-like setting is ideal for crows, said Dave Miller, director of facilities planning and management operations.

"The campus has light, warmth and tall, mature trees -- all the things that they like," he said.

However, the warm feelings the crows have for campus aren't reciprocated.

"They're noisy, they make a mess and they scare people," Miller said.

The roust

FPM's solution is to roust the crows from their roosts. Keeping the crows on the move, even if they're only moving around campus, keeps the birds from causing too much trouble in one place.

"Our goal is to make sure they don't pattern themselves in an area," Miller said.

After years of experimentation on a variety of crow-scaring tactics, FPM staff have settled on two techniques to keep crows from settling in.

Portable audio boxes that play crow distress calls have proven useful in chasing crows from a favorite spot. Six units that randomly play crow distress calls in the evenings are rotated around the rooftops of campus buildings.

"We don't leave the boxes anywhere too long," Miller said. "Otherwise, the crows will get used to them and pay no attention."

The annoying red dot

A second useful crow crowd disperser is a hand-held laser designed for bird control. The device, which looks something like a state trooper's speed gun, can shoot a red laser beam into a tree a hundred yards away. When the red light starts dancing around a tree teeming with crows, the birds take off, Miller said.

Still, get used to the crows. Several thousand crows congregate on campus every fall and winter. They usually hit their peak numbers in December.