Federal agents killed 6,421 wild animals at Denver International Airport last year and hazed away more than 130,000 in their quest to protect airplane passengers from wildlife strikes.
The list of 48 species trapped, poisoned or shot included sandhill cranes (10), feral cats (3) badgers (4), red-winged blackbirds (1,031) and even Colorado’s state bird, a small sparrow called the Lark Bunting (19).
Some animals, including 54 red-tailed hawks and 41 great horned owls were trapped and relocated instead of being killed.
Despite these efforts, the airport reported a record-high 878 wildlife strikes with planes last year.
And the numbers have been trending up.
The near worst-case scenario happened in April when a United Airlines flight departing DIA reported striking a wild animal and was forced to turn around and land with a burning engine.
But could more have been done to protect both wildlife and humans?
KUNC News recently obtained a document published a month before that damaging wildlife strike that suggests ongoing issues with the airport’s infrastructure are drawing more wildlife to the tarmac and contributing to a growing safety risk.
DIA and the federal agency charged with reducing the risk of wildlife strikes at the airport declined interviews with KUNC News. But records obtained through the Colorado Open Records Act shed light on what’s happening behind the scenes and contributing to the problem.
Weak fences and drainage issues
DIA contracts with the U.S. Department of Agriculture to manage wildlife risks with an agency called Wildlife Services.
And each year, the agency documents their activities, tallies their kills, records the number of animal strikes and makes recommendations to airport officials on how to reduce the risk.
In 2024’s report, the list of ongoing vulnerabilities was long. It showed despite the work of a four person-team of biologists and wildlife experts using pyrotechnics, traps and gunshots to haze and kill animals, life is finding a way at DIA.
Agents said coyotes, badgers, foxes and other small animals are digging under the airport’s perimeter fence and it should be strengthened.
“The current airfield fence is adequate for excluding deer and antelope, but Wildlife Services lethally removed an average of 581 rabbits, 102 coyotes, six foxes, nine raccoons, and two badgers from the airfield annually,” agents wrote. “Additionally, 309 rabbit, 18 coyote, seven skunk, and one raccoon strikes have occurred at DEN since 2018.”
Drainage issues around specific runways are also attracting wildlife to the airport, according to the report
Agents said standing water pools up after rain events and creates wetlands right off the runways.
“Surface water may not always be present in these areas, but many have been observed to attract waterfowl, prevent timely mowing, and exceed the (Federal Aviation Administration’s) recommended 48-hour max drain period,” agents wrote. .”These areas should be re-graded or otherwise designed in a manner which prevents standing water.”
The agency documented broken chains that had been previously installed to prevent cliff swallows from nesting near the runways.
It also recommended removing multiple trees near the runway that have been attracting bald eagles and other large perching birds.
“In the plains, landscape trees are “hotspots” for wildlife activity,” agents wrote. “Bald eagle strike locations may be correlated with the presence of trees in some areas.”
Agents also said an obsolete canopy structure at the airport had become a nesting site for feral pigeons.
A growing risk
Wildlife Services said a number of other things are contributing to the rise in bird and animal strikes each year at the airport.
They include increasing air traffic and development near the airport that pushes wildlife closer to the undeveloped land near the runways.
But this year’s record high number of animal strikes reported at DIA comes with a big asterisk.
Wildlife Services said there are “likely errors” in the 2024 bird strike dataset because a new version of a reporting system was deployed in August and there are likely duplicate entries.
“There is currently no known way to determine which strike entries may be duplicated,” agents wrote.
Still, the report says strikes were trending 11 percent higher over the previous year when the errors started late in 2024.
The risk of strikes is greatest in the summer and fall during migratory periods for birds.
Horned larks, cliff swallows, western meadowlarks, white-tailed jackrabbits and morning doves are the top five species struck at DIA.
