LONGMONT, Colo. -- Vance Brand Municipal Airport in Longmont is trapping and killing dozens of prairie dogs that have threatened funding for the facility.

In an operation starting Monday, trapped prairie dogs will be euthanized with carbon dioxide and donated as food for centers that care for injured raptors. Remaining prairie dogs will be exterminated in their burrows using aluminum phosphide pellets.

Airport manager Tim Barth says the trapping will cost the city $6,848 and the poisoning will cost $1,740.

The rodents had threatened airport funding from the Federal Aviation Administration, which said the animals' burrows posed a safety concern for pilots.

The airport tried containing prairie dogs with a $12,700 fence, but it wasn't enough, and it was torn down in December.

Barth told the Longmont Times-Call that the FAA reviewed the fence, "and they feel that the barrier fence we constructed wasn’t effective enough at containing the prairie dogs.”

In a Nov. 13 letter to the city, FAA officials wrote that "all prairie dogs must be removed from airport property before the Federal Aviation Administration will grant future funding under the Airport Improvement Program."

The city will capture the prairie dogs and donate them to a raptor rehabilitation program as food for birds of prey, he said.

“Anything that we can’t trap will be euthanized,” Barth said.

That also includes all prairie dogs on the Public Works Maintenance Facility property just north of the airport, according to the Times-Call newspaper. When the city receives grants from the FAA, it agrees to certain assurances -- including that the city will do its best to maintain “compatible land uses” on adjacent properties.

“That public works property does have a bunch of prairie dogs on it, and they have migrated over to the airport,” Barth said. “The FAA noted that, if they aren’t removed, they are just going to reinfest the airport.”

According to the city’s 2009 prairie dog survey and habitat assessment, which was done late this summer, there are about 155 prairie dogs and 435 burrows in the containment area at the airport. An estimated 97 prairie dogs and 260 burrows are on the public works site.