Powell-area sheep part of regional bighorn study

By: AP
By: AP

Powell, WY (AP) -
The dart swatted the bighorn sheep ewe square on the rump, making her a winner of sorts.

Little did the ewe know she had been picked to be included in a multi-state study between Wyoming, Colorado and Montana. The Wyoming Game & Fish Department and others are endeavoring to ascertain why bighorn sheep in the Cody region are doing well despite pathogens that can cause disease.

They plan to use that knowledge to understand why other bighorns around the West packing the same pathogens are not faring quite as well.

On Feb. 19-20, 16 bighorn ewes and one ram were captured on the North and South Forks of the Shoshone River.

This is the second year of a three-year multistate study to determine how bighorns cope with disease, said Hank Edwards, Game & Fish laboratory supervisor from Laramie.

After standing with a tranquilizer dart protruding from her butt for a few minutes, the ewe tried to walk, but her front legs appeared made of jelly and her head drooped.

Another ewe watched like a teetotaler scowling at the town drunk. After a few minutes the drugged bighorn folded into the ground and two Game & Fish staffers dashed to her for a quick and safe transport to a pickup truck.

All the ewes will be hauled to the Thorne-Williams Wildlife Research Unit (formerly Sybille) near Wheatland where she and others of her species will be closely monitored.

The goal is to map where pathogens occur and in which herds. Researchers will then link the pathogens to the herds' overall health to determine how the bighorns are coping with the pathogens, Edwards said.

The 16 bighorns captured near Cody will join 12 bighorns from central Colorado as part of the project.

Lambs in that Colorado herd did not survive to adulthood. Over the next two or three years, the researchers plan to ascertain why the Cody sheep tolerate the pathogens, then determine how that tolerance can build immunity by uniting the Cody and Colorado sheep, Edwards said.

Individually or in concert, Mycoplasma ovipneumoniae, Bibersteinia trearealosi and Mannheimia areaemolytica have been linked to pneumonia in bighorns across the West, but the Cody area bighorns carry all three pathogens, "and they're doing quite well," Edwards said.

"There are over 4,000 (bighorn) sheep in the Absaroka Mountains," said Doug McWhirter, Cody Game & Fish wildlife biologist.

There are an estimated 5,400 bighorns across the state, said Al Langston, Game & Fish spokesman in Cheyenne.

From their first summer to their first fall, lamb survival is about 25 to 35 percent for the Cody-area bighorns, which he ranks as pretty good around here, McWhirter said.

In hunt area 1, near the Clarks Fork of the Yellowstone River, the 20-year average is 33 lambs per 100 ewes. In area 2 near Trout Peak, the average is 32 per 100.

In area 3 near Wapiti Ridge, the average is 28/100. In area 4 near Younts Peak, the average is 29 per 100. In area 5 near Franc's Peak, the average is 29 per 100.

In areas 8, 9, 10 and 23, near Whiskey Mountain, the average is 24 per 100. In area 7 near Jackson, the average is 43 for every 100.

The Whiskey Mountain bighorns near the Dubois area suffered poor lamb ratios, but those numbers are improving, McWhirter said. The figures are according to the Wyoming Game & Fish Department.

Before traveling to Thorne-Williams, the captured bighorns were examined.

Edwards and Jessica Jennings, Game & Fish wildlife disease biologists from Laramie, collected blood samples to analyze DNA and search for prior disease exposure, nasal and tonsil swabs to search for the three pathogens, ear swabs to search for the scabies mite, and feces samples to search for lung worms and other parasites.

"We bring the lab with us," Edwards said.

Thus far, they have examined about 100 bighorns in Wyoming this winter. On this trip, the goal was to capture ewes only. It takes about 10 minutes to collect their samples. Once done, the sheep were given another drug to counteract the tranquilizer, Edwards said.

All the sheep captured were destined for Thorne-Williams with the exception of a ram that was examined and released, Edwards said.

One sickly orphan lamb was found in a cave on the North Fork. They tried to save the failing baby but failed.

"She didn't make the trip back," Jennings said.

The first South Fork sheep arrived in back of a pickup with its head cradled by a Game & Fish staffer. The ewe was blindfolded to keep her calm.

The scientists collected their samples in the back of a straw-lined horse trailer while a group of youngsters from Valley School watched. Jennings launched into teacher mode, and the kids were captivated.

"You ever see sheep poop?" Jennings asked.

"Yeah," was the delighted reply from the elementary-aged students.

Taking just a few head from the North and South forks will go unnoticed by area residents who enjoy driving out to see the wild sheep visible along the highway during the winter. There are not too many places where folks can enjoy the amazing opportunity to view bighorn sheep so close at hand, McWhirter said. This research can help spread that joy across the West.

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