JACKSON, Wyo. — A University of Wyoming research team is exploring using contraception as an alternative — and possibly more effective — solution to controlling coyotes.
The group, led by zoology doctoral candidate Marjie MacGregor, displayed its research at the International Conference on Fertility Control in Wildlife held recently in Jackson.
The technique uses deslorelin, a hormone that renders coyotes sterile.
Coyotes tend to prey on larger animals, including domestic sheep, pronghorn antelope and mule deer, more heavily when they have pups, MacGregor said. Because coyotes quickly fill territory left empty when their counterparts are gunned down, contraception has potential to reduce depredation better than killing, she said.
"The whole issue of coyote control is somewhat off the radar in Jackson Hole, where there's limited animal agriculture," MacGregor said.
"I'm not sure if Jackson Hole people think about how we manage coyotes across the state of Wyoming," she said. "They are overshadowed by the larger predators."
Numbers from the U.S. Department of Agriculture's Wildlife Services show coyote depredation across the state is a major issue.
From 1998 to 2008, Wildlife Services killed more than 77,000 coyotes in Wyoming — the second highest state total, trailing just Montana. The carnivore comprised some 94 percent of all the mammalian predators the agency killed in Wyoming during those 10 years.
A small percentage of the total coyote population, estimated at 50,000 to 80,000 in Wyoming, is killed each year, Wildlife Service's state director Rod Krischke said.
Wildlife Services hasn't removed coyotes from Teton County "in many years," Krischke said.
The agency director was familiar with the research and agreed with MacGregor's premise that contraception could be an effective means of reducing depredation.
"Basically, if you reduce the reproduction capabilities then you have fewer mouths to feed," Krischke said. "The hope's that the territorial coyotes would maintain their territory even though they're not having pups."
According to MacGregor's paper, "Chemical Castration of the Coyote," studies conducted in Utah and Colorado confirm that lamb and pronghorn fawn survival rates are higher in sterile versus intact coyote territories.
However, surgical sterilization programs — the only proven method — are not cost effective, the paper said.
Chemical sterilization is intriguing because of its lower cost and because it could potentially be used on a large number of coyotes, MacGregor said.
"The most important step is making sure the drug works — that we can stop the animal from reproducing," she said.
"We're still thinking about how it's going to be implemented in the field."
If that day comes, Krischke said, he'd "absolutely" consider using chemical contraception as a means of coyote control.
"If we could find tools that would resolve the damage situation without removing the coyotes, that's a win-win," he said.