Wildlife experts at O'Hare International Airport hope the grape flavoring used in Kool-Aid will encourage pesky birds that endanger planes to satisfy their appetites elsewhere.

Not far from steel traps baited with live pigeons to catch raptors on airport property and propane cannons used to scare away bird flocks, a series of hazing machines borders the 105-acre water retention pond known as Lake O'Hare.

The devices, part of the newest experiment to control animal populations on the airfield, spray a grape-scented mist that was distinguishable even in the wind Wednesday from the strong odor of jet fuel vapors.

Aircraft emissions don't cause birds to fly the coop, mainly because O'Hare's 7,800 acres are a tantalizing dinner platter. But the nerve endings in birds' nasal passages are easily irritated by the grape extract contained in a chemical cocktail called methyl anthranilate, according to Richard Dolbeer, national coordinator of airport wildlife services at the U.S. Department of Agriculture.

"The grape flavoring acts as a repellent, like a bird tear gas," Dolbeer said. "Methyl anthranilate is actually a non-toxic food flavoring that is used in grape Kool-Aid and grape bubble gum, but birds find it very aggravating.

"To us, it would be like the smell of ammonia salts," he added.

Officials said it's too early to tell whether the trials, conducted with the help of BirdTec Inc. of Hersey, Mich., will be successful in shooing away birds.

It is among emerging technologies, both high-tech and simple, that are being tested at O'Hare because of recent incidents involving birds sucked into airplane engines.

Other tools in the arsenal include paintball guns and a laser-beam gun, called the Avian Dissauder, that birds find annoying.

The airport also drains Lake O'Hare when it is not needed for water retention. In addition, officials are monitoring research on a new variety of fescue grass that tastes bad to birds and an early warning bird-detection experiment at Dallas-Fort Worth International Airport. The system uses a special radar to provide real-time alerts to air-traffic controllers and pilots to keep planes away from dangerous bird concentrations, just as radar warns pilots about wind-shear on runways.

Bird strikes, a national problem at airports that resulted in almost 6,000 incidents involving commercial planes last year, are an extraordinary danger this time of year when migrating birds compete for the same airspace with planes taking off and landing, according to the Federal Aviation Administration.

The number of incidents at O'Hare declined from 173 in 2000 to 139 last year due to enhanced mitigation efforts, according to the Chicago Department of Aviation. But officials said more can be done to lower the toll.

During takeoff, pilots try to climb as quickly as possible because about 75 percent of bird strikes occur below altitudes of 500 feet.

"For every takeoff, we require the pilots to turn on the bright lights on the nose gear and to use the wingtip-mounted landing lights as well to give the birds a better chance of seeing us," said Capt. John Jirschele, director of flight for American Airlines in Chicago. "But the wildlife people tell us that the relative quietness of today's modern jet engines actually plays against us, because the birds don't hear us coming."

Another effort to make O'Hare inhospitable to wildlife involves placing wire grids over Willow Creek, near Higgins Road on the northeast side of the airport. The closely spaced wires make it hard for Canada geese to splash down on the water because, like large aircraft, the big honkers require a long glide path.

"The geese can't just land straight down like a duck," said Kirk Gustad, Illinois director of wildlife services for the USDA. "They see the wires while on their glide slope and realize they can't get to the water."

Although most bird strikes do not cause significant damage to aircraft, more than 195 people have been killed worldwide since 1988 in accidents involving birds and planes, according to Bird Strike Committee USA, a group of government and aviation industry officials.

The latest incident connected to O'Hare occurred Nov. 2 when an American Airlines jet bound for New Orleans ingested at least one bird into an engine moments after takeoff at an altitude of only 200 feet. The McDonnell Douglas Super 80 made an emergency landing.

On Sept. 16 six double-crested cormorants were drawn into an engine of another American MD-80 (this sentence as published has been corrected in this text). Pieces of the engine, which was destroyed, rained down on several suburbs.

A United Airlines Boeing 767 bound for Brazil returned to O'Hare Oct. 24 when a bird got caught in an engine.

The federal government does not fund the wildlife mitigation programs at airports. The city Aviation Department and the airlines pay for the two USDA wildlife biologists stationed at O'Hare and wildlife biologist at Midway Airport. The program costs about $200,000 a year, said William Lonergan, deputy aviation commissioner for airfield operations.