Transplants of desert bighorn sheep by Colorado Parks and Wildlife have helped to establish a thriving population of the animals in the Dolores River canyon in far western Colorado, biologists from the agency have found.
In 2010 and again in December 2011, wildlife biologists captured and transplanted the desert sheep from an area south of Slickrock to the middle Dolores River canyon about 20 miles to the north near the Paradox Valley. That location was selected because the area provides ideal habitat for the animals and few sheep had been spotted in that location over the past decade.
In 2010, 15 sheep fitted with GPS radio collars were transplanted, on Dec. 17, 2011, 15 more sheep, also fitted with collars, were transplanted. All but one of the animals from the 2010 transplant survived, and one animal returned to the Slickrock area. In addition, several of the transplanted ewes gave birth to lambs which have also survived.
Desert bighorns are native to arid regions of the West. These animals -- slightly smaller than the high-country Rocky Mountain bighorns -- are well-adapted to desert canyons.
As biologists tracked the sheep transplanted in 2010, they were pleasantly surprised to learn that the newcomers had found a band of desert sheep that were already living in the rugged canyon country.
"What we've learned is very encouraging," said Brad Banulis, terrestrial biologist for Colorado Parks and Wildlife for the Montrose area. "There are more resident sheep in that area than we realized and the transplanted sheep have joined up with the existing herd."
Sometimes established herds will not accept transplants. Consequently, the new animals must learn the new terrain on their own which often results in reduced survival.
Biologists now estimate that the herd in that area now numbers about 60 sheep, including the transplants.
Besides being welcomed to a new wild home, introduction of new sheep increases overall genetic diversity of the herd as the animals breed, another important factor for long-term survival, Banulis explained.
Tracking movement of the collared animals will continue to help biologists learn more about the type and expanse of terrain the animals use. This will aid biologists as they continue work to encourage expansion of the herd.
The GPS collars last about three years, Banulis said. Biologists will continue to track the animals captured in 2010 for another two years, and the animals trapped in December until late in 2014.
"We'll be gathering a lot more data which will enable us to learn even more about desert bighorns," Banulis said.
No further trap and transplant operations for bighorns in this area are planned.
Two other desert sheep herds exist in the state: one in Colorado National Monument west of Grand Junction and one in the Escalante/Dominguez Canyon area west of Delta.
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