Fatal Disease Has Found Its Way To Badlands Bighorn Sheep

SPEARFISH, S.D. (AP) — The bighorn sheep in Badlands National Park are experiencing a die off caused by the same bacteria that has ravaged the other wild sheep herds in the state as well as countless others throughout the West.

Since August, when the first sheep in the park were found suffering from the disease, approximately 50% of the radio-collared ewes have been found dead – all from mycoplasma ovipneumoiae, a pneumonia-causing bacteria that nearly wiped out the Custer State Park herd and has wreaked havoc on the Rapid City and Deadwood herds.

The sheep are experiencing the early stages of the die off, and wildlife managers are still taking stock of the situation, the Black Hills Pioneer reported.

“We don’t have a real good handle on it at this point, but it’s safe to say it is significant at this point,” said Trenton Haffley, regional terrestrial resources supervisor for South Dakota Game, Fish, and Parks.

He said the most accurate data wildlife managers can see now is by looking at the number of sheep wearing radio collars. Only ewes in the park’s herd, the female sheep, were fitted with collars.

“Adult ewes experienced about a 50% mortality. Generally, lamb mortality is higher,” Haffley said. “Then of course rams, it’s a wild card. We don’t know what’s going on there.”

A survey was conducted in July and approximately 260 individual sheep were counted.

“Realistically, there were closer to 300 animals,” he said.

Wildlife managers know that domestic sheep and goats can carry the bacteria and then transmit it to wild sheep and goats. It is the GF&P’s policy to euthanize wild sheep that have come in contact with domestic flocks to prevent further exposure to the remaining bighorns.

“We got reports of wandering rams this summer. We just were not able to track them down and euthanize them. So, likely they went out, found some domestic sheep, came back, and got everyone sick,” Haffley said.

Other wildlife departments have the same policy. Grand Teton National Park has, for the past two years, permitted trained hunters to hunt and kill non-native mountain goats inside the park to help prevent the spread of the bacteria to the park’s declining but native bighorn herd.

“Usually the bighorns that travel are young rams,” Haffley said. “Mom doesn’t want them around, and the older rams pick on them. Those are the ones that go out and pioneer.”

Because the die-off is in its early stages, a plan on how to manage it has not been set in place.

“All we’ve done so far is met with the park and said ‘we’re here for support if you need it,’ because we are so early in the die-off. Unfortunately, we just have to let the thing play out,” he said.

GF&P employees have seen the sheep actively coughing as recent as last week, but there have been no reports of dead sheep in more than a month, Haffley said.

“That suggests that it might be winding down, but in that country, it’s going to be kind of hard to turn up (dead sheep) anyway,” he said. “We will likely get to a point where we will partner with Badlands National Park and do some kind of test and cull. But it will be up to the park.”

GF&P researchers will likely use lessons learned from the Custer State Park bighorn sheep die off. In 2004, the 200-plus animal herd began to die from pneumonia. Around 80% of the herd died before the adults gained an immunity; however, the lambs born each spring contracted the disease and within months were dead. Then in 2017, biologists discovered that only three of the sheep were shedding the pathogen that spread the disease. Those sheep were removed from the herd, and since then, the lambs survived.

Haffley said that GF&P wildlife managers have responded to reports of and euthanized bighorns throughout the western part of the state.

“We’ve caught up to them in Ziebach County (northeast of the park and Interstate 90),” he said. “We actually had four yearling rams we found on Haines Avenue, which you might not think is a big deal as we have sheep in Rapid City, but at that time, we were so far into the die-off in Rapid City that we didn’t have four yearling rams in that herd. We knew those rams did not come from Rapid City. They moved 45-50 miles from Badlands, and actually almost got into our bighorn sheep in Rapid City before we euthanized them. They can move really far really quickly.

“I just can’t reiterate enough how important it is for the public to call us. Whenever you see a bighorn sheep and you don’t think it is supposed to be there, call us,” he said.

Exactly where or how the bighorns contracted the bacteria is not known.

Haffley said there is a domestic goat flock about a mile and a half north of the park boundary. “One of the odd things is the sheep have gone by the domestic flock all the time,” he said. “The owners of the goats allowed us to go in and do a bunch of testing, and we definitely found mycoplasma in the goat herd, and those bighorn have lived sympatricly for probably 10 years. It hasn’t caused any issues. We are doing some strain typing that may point us in the direction of was it sheep or goats that caused the die-off, but we just don’t know.”

While the Custer State Park herd is recovering, other herds in the state are not out of the woods yet.

Haffley said the Rapid City herd is beginning to recover from its die off. Only five or six ewes can still give birth, but those lambs are surviving and being recruited into the herd. Between 25-30 sheep are in this herd.

The Deadwood herd, transplanted from Canada in 2015, began showing signs of pneumonia the following year. All had been tested before being relocated, so it is not know how they are contracting the disease.

“In November we tested and thought everyone was clean. There were a few sheep left, but we took some samples from lambs and thought we were in a good place,” he said. “But low and behold, about a month ago, we had reports of coughing sheep. We had a lamb die in someone’s backyard. We went up there and grabbed some samples, and that one came back positive for pneumonia.

“We’re going strain typing to see if it is the same strain we’ve been dealing with previously,” he added. “If that’s the cause it means we’ve missed one, and we’ll be in there doing additional testing. If it’s a new strain though, or there is evidence of additional contact, that begs the question of some longer-term discussions.”

The approximate 30-animal herd may lose some members if the strain is the same; however, if the bacteria is a new strain, a greater number would be expected to be lost, he said.