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 said.
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.
The problem is that mountain goats seem to like the same habitat as bighorn sheep. 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," continued Garrott.
Mountain goats also carry many of the same diseases and parasites as bighorn sheep, but may be less susceptible to the pathogens, Garrott said.
For all the concerns, there's no way to know how the mountain goats will affect bighorn sheep, say Garrott and other biologists. Only more research can provide the final answer.
Park Service policy dictates that non-native species be eliminated.
Reprinted in part from Casper Star Tribune