GREEN RIVER, Wyo. — Wildlife officials say bighorn sheep from Oregon released last year in the Seminoe Mountains in south-central Wyoming are doing well.
At least a dozen lambs were documented this spring from last winter's transplant.
Those lambs are going to get a visit from their Oregon cousins when wildlife officials head back to the Beaver State next month to capture another 20 bighorns for release into the growing Seminoe Ferris herd.
Wyoming Game and Fish Department bighorn sheep coordinator Kevin Hurley said the agency anticipates — if the capture operations go as planned — the bighorns will be released into their new home around Dec. 2.
The 20 bighorns will come from the lower John Day River area in north-central Oregon.
He said to help the sheep get a jump start on their new home, coyote-control efforts will be instituted this month before the release.
“This will help the sheep avoid predation until they become familiar with their new surroundings,” Hurley said.
The coyote control work will be conducted with the assistance of USDA/APHIS Wildlife Services and the Carbon County Predator Management District, with funding provided by the Wyoming Animal Damage Management Board and the Wyoming Wild Sheep Foundation.
The proposed capture and transplant operation is part of a larger project that aims to supplement the dwindling herd with about 60 sheep overall.
The December infusion of another 20 bighorns would be the third supplemental population boost for the beleaguered Seminoe Ferris herd in a year.
Game and Fish biologists released 20 Oregon sheep into the area on Dec. 2, 2009.
The sheep were released into the rugged hills within the Morgan Creek Wildlife Habitat Management Area in the Seminoe Mountains of Carbon County.
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Agency biologists released another 12 bighorns into the herd that were captured from the Devil's Canyon herd near Lovell on Jan. 3.
Plans to transfer an additional 40 bighorn sheep from Antelope Island in Utah's Great Salt Lake were canceled when the sheep became unavailable.
One of the Oregon ewes died from capture-related injury during the first transplant in December 2009, but the rest of the relocated bighorns appear to be doing just fine, Hurley said.
Game and Fish biologist Greg Hiatt said agency personnel have been flying over the Seminoe range every month to monitor the movements and locations of the sheep.
“So far, we have had no mortality on any of the radio-collared sheep,” Hiatt said in a media release.
Hurley said biologists typically try to get a 3-to-1 ratio of rams to ewes in the gender mixture for transplanted bighorns.
Last year's transplant from Oregon's lower Deschutes River included 15 ewes and five rams. Hurley said game managers will be looking for a similar mix for the upcoming transplant.
Hurley said biologists generally try to capture young rams from 1 to 4 years old for transplant. The sheep will be net-gunned from a helicopter and then transferred to modified horse trailers for the 900-mile, nonstop ride to Wyoming, according to plans.
The majority of the transplanted bighorns will again be fitted with GPS collars. This allows biologists to closely monitor the animals' seasonal and daily movement patterns and habitat preferences.
The Seminoe Ferris bighorn herd used to number in the hundreds, but decades of drought, poor forage conditions and threats from disease and predators have taken their toll. Herd numbers fell to around 20 sheep in early 2009 before the first transplant.
Hurley said the Oregon bighorns are a good match for the Seminoe Ferris herd, in part because they are better suited to lower elevation areas and can better adapt to the short, early forage season in the Seminoe Mountains.
“With the Oregon sheep, we are trying to do a better job matching source sheep to target habitat,” he said. “And the lambing period of the Oregon sheep will more closely coincide with the peak green-up of vegetation in the Seminoe Mountains.”