Every winter government sharp shooters in helicopters and low-flying planes kill more than 30,000 coyotes and other predators that have been preying on sheep and cattle. Now a coalition of environmental and animal protection groups want the practice stopped — despite arguments of ranchers who say the program is vital.

"Once a coyote gets a taste for lamb, it keeps coming back," says John Carpenter, a Nevada state assemblyman who recently owned 20,000 sheep and 8,000 cattle. "You need trained pilots and marksmen to be able to get them."

The coalition of 14 advocacy groups filed suit in federal court this week to end the program, which is conducted by Wildlife Services and overseen by the U.S. Department of Agriculture. They claim the gunning of wild predators is unproductive, costly and occasionally dangerous to people (Wildlife Services has crashed 17 helicopters or airplanes while hunting predators, killing seven people since 1989).

"It's not right that the federal taxpayer pays for another subsidy for livestock owners," says Wendy Keefover-Ring of Sinapu, a Colorado-based, non-profit predator protection program which was part of the coalition, AGRO, that filed the suit. "Plus it doesn't work and it's unethical."

Wildlife Services officials declined to comment on the suit but said in a statement to ABCNEWS.com, "The use of aircraft … is key to supporting overall WS ground operations in an effort to reduce predation by coyotes to livestock."

A Clever, Flexible Foe

USDA records show wild predators caused more than $15 million in damage to U.S. livestock owners in 1998 by killing calves, lambs, sheep and goats. Coyotes do more than half of the killing, although dogs, mountain lions, cougars and foxes are also known to stalk and kill livestock.

"You're never going to get rid of coyotes, they're too clever," says Carpenter. "They leave a very tell-tale sign. You find two to three teeth marks on either the top of the head or the windpipe."

Some scientists have questioned whether killing coyotes is an effective way to reduce their kills.

Robert Crabtree, a Montana biologist and coyote specialist, has argued killing coyotes can actually trigger an increase in the wild canine's numbers. His studies have shown by killing adult coyotes, more food is left for pups and so more pups reach adulthood. Normally only one to two pups from coyotes' six-pup litters survive.

Furthermore, aerial gunnings often target the leaders of coyote packs, known as the alpha male and female, since these are usually the only animals in a pack which breed and often kill livestock to feed their young. Crabtree's studies have shown by killing a pack's alpha pair, the program effectively relieves a pack of its hierarchy and allows more coyotes to breed, again increasing coyote numbers.

The coalition AGRO cites Crabtree's work in their arguments against the USDA program. Rather than killing wild predators, the groups say ranchers should protect their livestock by increasing fencing, using dogs and burros as guards and placing pregnant sheep and cattle inside barns.

But Frederick Knowlton, a research wildlife biologist at the National Wildlife Research Center in Logan, Utah, questions Crabtree's findings. He says Crabtree's own data show if you leave coyote packs alone, their numbers decrease only 5 percent of the time — when the pack leaders are too old to have several pups.

Otherwise, says Knowlton, "killing coyotes is an effective way to reduce livestock kills."

Counting Dollars

The cost of the program, which reaches up to $10 million a year, has drawn politicians to the debate. Rep. Joe Skeens, a republican New Mexico rancher has championed the program while Reps. Peter DeFazio, D-Ore., and Charles Bass, R-N.H. have pushed for amendments to curb Wildlife Services' spending.

"The program may provide a good service but the efforts are geared toward subsidizing ranchers," says Kristie Greco, a spokesperson for Rep. DeFazio. "And despite an increase of funding, there has been no decrease in the number of livestock killed."

DeFazio's office reports between 1983 and 1993 budget spending increased for predator kills, but the number of livestock taken by coyotes still increased by 30 percent. The numbers suggest that despite government efforts, coyotes may still be too cunning to stop.