JACKSON, Wyo. (AP) — Non-native mountain goats have gained a foothold in parts of the Greater Yellowstone Ecosystem and could threaten native bighorn sheep, including the Teton Range bighorn sheep herd, biologists say.
Researchers from Idaho, Montana and Wyoming have joined forces to study the hardy, aggressive invaders, which have likely begun breeding in the Teton Range.
“They don’t get much attention,” said Bob Garrott, director of Montana State University’s Fish and Wildlife Ecology and Management Program, and leader of the research effort.
“Learning more about their population ecology and spacial ecology can help inform management and conservation.”
Garrott and his colleagues are capturing mountain goats and outfitting them with two different collars. One collar contains a Global Positioning System device that records the goat’s position every six hours for two years.
When that falls off, another activates to give wildlife research less specific data for the next four years.
Researchers will gather data from 12 collared goats captured in the Palisades Range along the Wyoming-Idaho border southwest of Jackson Hole. They will be looking for the types of habitat goats use, whether they have offspring and how long they survive. That data will then be compared to bighorn sheep research.
“The study areas that we have are the Palisades, where we have goats and no sheep, and the Gros Ventre ... where we have sheep but no goats,” Garrott tells the Jackson Hole News & Guide (http://bit.ly/y2oclF).
Researchers also plan to capture both goats and sheep in the Cody area, where the two species occupy the same mountain ranges. In Montana, researchers will study both goats and sheep around Gardiner.
Mountain goats were introduced into mountain ranges in the region, including the Palisades Range, by wildlife managers in Idaho and Montana a few decades ago, “and they’re doing quite well and expanding their range,” Garrott said.
Since then, the goats have popped up in various locations around Jack son Hole, Wyoming Game and Fish wildlife biologist Doug Brimeyer said.
“Right now where we’re seeing them is in the Teton Range north of Highway 22, and we get periodic observations of them in the Gros Ventre mountains and the Teton Wilderness,” he said.
One was photographed on Fremont Peak in the Wind River range two years ago.
The problem is that mountain goats seem to like the same habitat as bighorn sheep.
“There can be direct competition for food in the alpine and subalpine environments,” Garrott said.
Wyoming Game and Fish habitat biologist Aly Courtemanch, agreed.
She studied the Teton Range bighorn sheep herd as a graduate student at the University of Wyoming.
“In the Tetons, the bighorn sheep winter habitat is a relatively few isolated wind-swept slopes at high elevation, because they’ve lost their migration,” she said. “They’re already surviving on this marginal winter habitat up there.
“It’s reasonable to expect that mountain goats, if they became established, would out-compete bighorn sheep for that very limited winter range.”
And, when the two species go head-to-head, mountain goats probably win, Garrott said.
“There can be displacement of one species by the other,” he said. “It looks like goats are much more aggressive and much more protective of their individual space.
“They’re less social, they’re more aggressive, and they have a set of dagger-like horns. It looks like sheep will defer to the goats.”
Mountain goats also carry many of the same diseases and parasites as bighorn sheep, but may be less susceptible to the pathogens, Garrott said.
The issue is of particular interest in Grand Teton National Park, said Steve Cain, the park’s senior wildlife biologist, and Sarah Dewey, a wildlife biologist who is spearheading the park’s mountain goat research.
“Since the late ‘70s, we’ve had 74 reports (of mountain goats),” Cain said. “Thirty-eight occurred in the park.”
“For 2011, we had eight sightings reported, and they totaled 19 (animals),” Cain said. “Some of those are likely duplicate observations.
“We also had sightings that included adult goats with kids and the number of kids ranged from one to three. “There’s maybe six to 10 goats, but that’s a little bit of a stab in the dark.”
Beginning in 2010, Park Service officials began getting regular reports of goats in Grand Teton, Dewey said.
“That suggests to us that a population is beginning to establish here in the park,” she said.
Still, for all the concerns, there’s no way to know how the mountain goats will affect bighorn sheep, say Cain, Garrott and other biologists.
Only more research can provide the final answer.
Park Service policy dictates that non-native species be eliminated.
“The park is currently in the very beginning stages of developing a management plan for goats, and we will likely look at several different alternatives,” Cain said. “That would include doing nothing, monitoring them and actually removing them, and we would look at different techniques for removing them.
“We would prefer to do it in a way that’s a little more transparent and work with people that might be interested in the issue,” Cain said.