CHEYENNE -- The Wyoming Game and Fish Department plans to supplement a dwindling bighorn sheep herd in south-central Wyoming with 60 animals from Utah and Oregon, a strategy officials hope will give the herd its best chance for survival.

Fewer than 20 sheep remain in the existing herd in the arid Ferris and Seminoe mountain ranges about 40 miles northeast of Rawlins.

The department plans to supplement the herd with 20 sheep from the Diablo Mountains of south-central Oregon and 40 sheep from Antelope Island in the Great Salt Lake of Utah in December and January. The department selected the sheep because they live in similar environments to the Ferris/Seminoe herd.

This is the first attempt to build the Ferris/Seminoe herd since 236 sheep from Whiskey Basin near Dubois were moved down in six different releases between 1957 and 1985, the department said.

The Whiskey Basin bighorn sheep "were adapted to different ecological conditions than conditions found in the Seminoe Mountains, and those differences may have contributed to poor lamb survival and limited population performance," said Kevin Hurley, bighorn sheep coordinator for the Wyoming Game and Fish Department.

"This time we are getting sheep from areas with similar ecological conditions in the hopes that this supplemental release will be more successful," he said.

The same strategy worked well in the mid-2000s when new sheep were introduced to Devil's Canyon near Lovell, he said.

Wildlife officials will capture, truck and release the Oregon sheep in early December. About five weeks later, wildlife officials will capture and move the Utah sheep.

Hurley said the project is timed for winter so the new sheep will include pregnant ewes. Breeding season for most bighorn sheep starts in one to two months. Transplant projects are typically carried out after the ewes are bred, Hurley said.

He said about two-thirds of the 60 new sheep will be adult ewes.

"And the following spring, we'll get a lamb drop, so we not only got the 60 sheep, but we got a whole bunch of new lambs that mamma was carrying inside of her," Hurley said. "It's a two-for-one kind of deal."

Wyoming is home to 6,000 bighorn sheep out of a West-wide population of about 70,000, Hurley said.

"Wyoming is a real big destination state for bighorn sheep hunting," Hurley said. "Ultimately, we'd like to have a healthy enough population in the Seminoes that we can offer some hunting opportunity, but realize that'll take a few years for that herd to get up to the point that they can sustain that sort of outtake."

The $150,000 project is jointly funded by the Game and Fish Department; the Wyoming Governor's Big Game License Coalition; the Wyoming, Eastern and Minnesota/Wisconsin chapters of the Foundation for North American Wild Sheep; the Wild Sheep Foundation; and the Grand Slam Club/Ovis.