BILLINGS, Mont. - Federal wildlife agents killed more than 1.6 million animals last year - including a record number of endangered wolves and more than a million birds - because of threats to livestock, crops and air travel.

The overall number was down slightly from 2005, when 1.7 million animals were killed, according to a recent federal report. But killings increased for several carnivore species including coyotes, foxes, and gray wolves.

Environmental groups seized on the figures to renew their call for the elimination of Wildlife Services, a division of the U.S. Department of Agriculture that removes animals at the request of the livestock industry, government agencies and others.

"We don't think the government should be in the extermination business," said Jeff Ruch with Public Employees for Environmental Responsibility.

A Wildlife Services spokeswoman described the agency as providing a crucial function, by protecting livestock producers from economic losses and air travelers from harm.

"We've seen coyotes on airports, and why are coyotes on airports? Because the gophers are there. We want to look at a way to remove their food base. But sometimes the means to the end is maybe removing those coyotes," agency spokeswoman Teresa Howes said.

Increasingly, Howes said, the agency's shooting, trapping and poisoning operations involve nonnative, or "invasive," species such as European starlings, a bird that is attracted to feedlots where they defecate in cattle feed.

Wildlife Services reported almost 64,000 cases of animals damaging or threatening to damage property or natural resources in 2006. Those ranged from beavers girdling trees and coyotes killing sheep, to birds strikes on aircraft and woodpeckers damaging buildings.

Howes added Wildlife Services also employs nonlethal tactics. Last year, it dispersed more than 24 million animals congregating around locations such as farms and airports by scaring them away with pyrotechnics, propane cannons and other methods.

More than 87,000 coyotes were killed by the federal government nationwide in 2006, the most since 2001. And 278 wolves were killed - a number that has risen steadily over the last decade in step with a recovering wolf population in the Northern Rockies.

Since wolves were reintroduced to the region by the U.S. Fish and Wildlife Service in the mid-1990s, their expanding population has caused increased conflicts with sheep and cattle ranchers in Idaho, Montana and Wyoming.

Howes said the removal of problem wolves helps ensure a tolerance for the animals in rural areas.

But Ruch, the environmentalist, said rather than killing them, the government should consider relocating wolves to areas like Rocky Mountain National Park in Colorado, where officials are struggling to rein in expanding elk herds.

Jim Magagna, executive vice president of the Wyoming Stock Growers Association, said he supported Wildlife Services and suggested eliminating the agency could drive some livestock producers out of business.

"From almost any perspective, it helps to have an organization out there, professional people, doing the predator control work rather than having a free-for-all," he said.