Denver Tries Fencing and Frightening Wildlife to Keep Runways Clear

Denver International Airport operations manager Mike Carlson and federal wildlife biologist Kendra Cross take an airport vehicle on a road parallel to runway 34 Right looking for a "coyote slide," where the animals have dug under DIA's perimeter fence.

Not far from Frontier Airlines' maintenance hangar, Cross finds where coyotes burrowed under the 8-foot-high chain-link and barbed-wire fence.

Planes hit coyotes at least three times last year at DIA, said Cross, the airport's principal wildlife biologist, who works for the U.S. Department of Agriculture. There are about 200 wildlife strikes annually at DIA.

About 85 percent of Cross' work is at DIA, but the job also takes her to other airports, including Grand Junction, Gunnison and Colorado Springs.

On Nov. 26 at DIA, an engine on a departing United Airlines 737 ingested what officials thought was a young coyote.

Pilots completed the takeoff but returned immediately to the airport so mechanics could assess the damage, which officials estimated at $50,000, Cross said.

From a freezer on the south side of DIA's Concourse A, Cross pulled out a large plastic bag with what she and her colleagues had judged to be the remains of a juvenile coyote killed in the November incident.

DIA employees collected the shredded animal parts from 200 feet of runway.

When wildlife officials cannot make a definitive identification of an animal, the remains are sent to the Smithsonian Institution, where DNA testing is used to verify the species, Cross said. In this case, the scientists determined the animal was a great horned owl.

At DIA, coyotes, geese and birds of prey - such as owls, hawks and eagles - are among animals that collide with planes.

To control them, wildlife biologists first try "habitat management," which includes fencing and limiting the presence of trees, shrubs or grasses that attract animals.

When that doesn't work perfectly, Cross and other wildlife biologists turn to "hazing and harassment," she said.

During the recent seasonal mass migration of geese, officers fired nonlethal pyrotechnic "bangers and screamers" from a shotgun and 15mm launcher to drive the birds away.

"Our scary devices sound like loud shotgun blasts," Cross said.

As a last resort, officers turn to trapping or poisoning.

"Lethal control is a necessary management tool," although it is only used 10 percent of the time, Cross said. "The reason why we manage prairie dogs, rabbits and other prey species is because they attract predators like coyotes, hawks, eagles and owls."

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