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South Dakota bighorn sheep populations impacted by disease

Bighorn Sheep

Photo credit: Dreamstime

Pneumonia, cliff falls, vehicle collisions. South Dakota’s Deadwood bighorn sheep herd has had a string of bad luck since 2016, including one ewe that starved to death after getting her head stuck under a log, according to Trenton Hafley, Regional Terrestrial Resources Supervisor for South Dakota Game, Fish and Parks (SDGFP). It’s been only four years since bighorn sheep were relocated to the northern Black Hills and, while mortality has been high, wildlife officials hope that by “removing a few troublesome individuals…they can return the herd to health,” the Rapid City Journal reports.

According to the latest SDGFP tally, the Deadwood herd is only 17 bighorn sheep strong. Of the original 26 that were relocated to the area in 2015, 25 have already died. And the rest of the herd is only one-to-two years old.

Pneumonia is behind most of the deaths. Thomas Besser, a bighorn sheep researcher at the Washington State University College of Veterinary Medicine, told the Rapid City Journal that the outbreak was started by a single member of the herd that then passed along the disease to the others.  

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“In most outbreaks, only a single animal contacts the source of the bacteria [domestic sheep] and gets infected,” said Besser. “From then on, it’s all wild sheep to wild sheep.”

It’s not a single Black Hill herd being affected. According to Hafley, the Rapid City herd and Custer State Park’s herd have also seen dramatic declines in population due to pneumonia; however, other herds in Jewel Cave National Monument, Badlands National Park and Elk Mountain remain unaffected. Right now, SDGFP is focusing on removing diseased sheep from the Rapid City herd. Next, eliminating sick animals in the Deadwood herd will be their focus.

“I’m 100 percent confident that in the next couple years, we'll be able to clean up this pneumonia outbreak,” said Hafley. “We’re working in Rapid City right now to get this thing cleaned up, and I expect that Deadwood will go just as well.”

1 Comment

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Carrie H. - posted 7 months ago on 01-29-2019 10:20:38 pm

The presence of M. ovi does not mean that an animal is diseased. M. ovi has now been detected in healthy Dall's sheep as well as mountain goats, caribou and moose in Alaska with one caribou mortality associated to the bacterium. 
Movi in wild sheep requires stressors such as illnesses, injuries and lac of access to quality foods, lac of adequate feeding ranges can force sheep and goats to lower elevations in search of food exposing them to more human activites causing stress.
The Alaska department of fish and game along with the state vet have som great research on M.ovi and continue to sample ather wildlife as well as to learn more about the causes and how it is spread.