HomeOutdoorsNewsBighorn Sheep Falling Victim to Mysterious Disease in the Rocky Mountains

Bighorn Sheep Falling Victim to Mysterious Disease in the Rocky Mountains

by Shelby Scott
(Photo by George Rose/Getty Images)

A mysterious disease has begun killing the bighorn sheep of the Rocky Mountains. In recent months, wildlife experts have counted dozens of dead sheep so far. However, they have not been able to determine the actual source of the infection.

According to Newsweek, the strange outbreak began killing bighorn sheep in the Bighorn Mountains of Wyoming back in October. The outlet reports that the Bighorn Mountains, a sister range to the famous Rockies, earned their name after the resident population of bighorn sheep in the area. Since then, 45 sheep have fallen victim to the mysterious disease. Experts state that the affected animals are located around Devil’s Canyon.

The loss of life in the area’s bighorn sheep population is significant because, at one time, hunters had driven the animals from their habitat. In 1970, the species was reintroduced there, and since then, the herd has grown to between 250 and 300 individuals. Thanks to the strange outbreak, however, more than 10% of the herd has been wiped out.

What makes the current outbreak even more unusual is that wildlife experts have found the infection to be affecting primarily ewes and lambs, rather than mature male bighorn sheep. Wyoming’s Game and Fish Department were first alerted to the jump in fatalities after the GPS collar on one sheep became immobile. A local hunter also contributed a report of their own.

Bacterial Infection Causes Lethal Pneumonia in Bighorn Sheep

After locating multiple bighorn sheep carcasses, wildlife experts conducted autopsies, swabbing nasal and tonsil swabs in a lab in Laramie. After examining the swabs, they determined the sheep had contracted a bacteria called Mannheimia haemolytica.

Per the news outlet, this particular bacteria is known to cause lethal pneumonia in bighorn sheep, and kills relatively quickly. Still, Corey Class, wildlife management coordinator for the Cody Region, said, “The source of the infection is unknown.”

Class further explained, “Mannheimia haemolytica was present in the herd already, but this is a different strain; [a] more virulent strain I guess, [a] more pathogenic strain.”

As experts work to determine the cause of the spike in bacterial infections, wildlife officials have headed to the Bighorn Mountains. There, they plan to collect the carcasses of the dead and dying animals. These efforts come as a method of preventing the spread of the disease. It also helps experts better protect the rest of the shrinking herd.

In addition, experts plan to pay closer attention to the GPS collars assigned to various sheep. This is so they can track later fatalities and the overall movements of the Rockies’ herd. Perhaps if collars become immobile in certain areas, experts will be able to determine what kind of environmental factor is playing into the spread of the disease.