Jeff Yost, a terrestrial wildlife biologist with the Colorado Division of Wildlife, describes how satellite collars on the Mount Zirkel Wilderness Area bighorn sheep have been yielding valuable information about the herd.

Photo by Matt Stensland

Jeff Yost, a terrestrial wildlife biologist with the Colorado Division of Wildlife, describes how satellite collars on the Mount Zirkel Wilderness Area bighorn sheep have been yielding valuable information about the herd.

Bighorn sheep return to Zirkel Wilderness Area

Satellite collars yield valuable information to gauge health of herd

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A reintroduced Rocky Mountain bighorn sheep stands on a rocky peak not far from 11,924-foot Mount Ethel and Luna Lake last summer.

— From his office, Jeff Yost can tell the herd of Mount Zirkel Wilderness Area bighorn sheep is flourishing.

“They’re doing great in there,” said Yost, a terrestrial wildlife biologist with the Colorado Division of Wildlife. “They’re traveling a lot. This particular herd of sheep has been really good at pioneering on their own.”

Yost did not have to fly over the area or hike into the Routt National Forest to know this. All he did Thursday was log on to a website and click on the sheep whose locations he sought. A map popped up showing the four sheep in the herd wearing satellite collars.

“Sure enough, there they are at the bottom of the canyon,” Yost said.

The bighorns residing along the Continental Divide in the Park Range are the result of a reintroduction project where 41 bighorns were released into Red Canyon in 2005, about 20 miles west of Walden in Jackson County. Today, the herd’s numbers likely exceed 75, Yost said.

It’s thought that at one point there were 800 to 1,000 Rocky Mountain bighorn sheep living in the Park Range, Yost said. They thrived on the forest land that Ute Indians had burned, clearing out heavy timbered areas to promote healthy grazing grounds. By the early 1900s, the burns became nonexistent, the habitat became less hospitable for the bighorns and disease may have contributed to the herds’ being wiped out.

The bighorn is Colorado’s state mammal, and DOW officials, including now-retired biologist Jim Hicks, worked for about 25 years to return the native species to its habitat in the Park Range. The Burn Ridge Fire in 2002 created the opportunity.

“We could never get the corridor from the winter range up to the summer range because they don’t like to go through timber, so we were afraid they would never move and get out of the canyon unless there was a fire,” Hicks said.

Expanding recreation

The DOW has been working closely with the U.S. Forest Service on the bighorn sheep project to reintroduce the native species and expand recreational opportunities.

“I like the wilderness to be complete, have all the pieces in place,” said Robert Skorkowsky, a wildlife biologist with the Routt National Forest. “If someone wants to see one in the Zirkels, we can kind of tell them where to go if they’re quiet and have a pair of binoculars.”

Seeing a bighorn sheep in the wilderness can be the highlight of a vacation, Skorkowsky said.

“It’s a cool darn project,” he said. “I’m really glad the bighorns are here.”

The reintroduction has open­ed up recreational opportunities for hunters. The DOW offered two tags in 2009 and 2010, and five tags are offered for fall to help keep population levels steady until a management plan can be adopted to outline the preferred size of the herd.

Data valuable

On March 26, a helicopter crew was used to net-gun nine of the bighorn sheep and attach four more of the satellite collars, which have yielded valuable date for those managing the sheep project.

The helicopter had to fly into the wilderness area, which required special permission from regional foresters.

The permission was granted, Skorkowsky said, because bighorns are considered a sensitive species by the Forest Service so they take a “heightened responsibility to make sure the populations are managed carefully.”

“They wouldn’t allow a helicopter to go radio collar elk up there,” Skorkowsky said.

The satellite collars are more expensive than traditional radio collars, costing about $4,500 each. At the same time, they save money because the DOW does not have to fly a plane overhead and search for the collars’ radio signals, which have a range of about a mile. The satellite collars were bought using $20,000 raised from the sale of sheep licenses that are set aside for auction.

“All that money goes back into sheep research,” Yost said.

The satellite collars transmit coordinates three times a day. The DOW has been able to track where ewes go when they have lambs, how the sheep migrate between winter and summer months and what kind of impact the lambs are having on the habitat.

All this data will be used to help the DOW come up with a management plan in the next year for the herd, which will “help maximize the amount of sheep we can have up there and keep in mind the health of the habitat,” Yost said.

“We don’t know how many can be supported,” he said.

The satellite collars further enable the DOW to determine how close the bighorns are to domestic sheep permitted to graze on federal lands.

“We don’t want bighorn sheep and domestic sheep to interact,” Skorkowsky said. “That’s

one reason we’re really interested in the information.”

Domestic sheep are carriers of a bacterium that is deadly to bighorns.

“If a domestic sheep got in the Zirkel herd, it would kill the whole herd, and no one wants to see that happen,” Skorkowsky said.

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