Every day without a “beep beep beep” in his earphones is a very good day for big game biologist Brett Wiedmann.
The beeps are a radio collar mortality signal, and they mean yet another of North Dakota’s prized bighorn sheep has died.
Since August, in what was a long deadly month, at least 20 of the animals have died of pneumonia in the northern Badlands habitat. Tests show the disease is from contact with domestic sheep. It is spreading among the several bighorn groups in what Wiedmann calls “the hub of the wheel” for bighorns.
As if the fatal disease weren’t bad enough, 14 of the dead were among a group of two dozen transplanted to the area in February from a pristine location in the northern Rocky Mountain region of Alberta.
Wiedmann, big game biologist with the North Dakota Game and Fish Department’s Dickinson office, said the illness is a two-part tragedy: It can kill all or most of the bighorns before it moves through, and the Alberta bighorns were showing such early promise in their new home.
He said the Alberta bighorns may be especially vulnerable because they were so pristine in terms of outside contact.
“It went from being a great project to a nightmare. I hate to see it,” Wiedmann said. “It’s terrible, the worst thing in the world. They are such a magnificent animal.”
There is no way to precisely count the mortality rate.
Wiedmann knows that at least 20 sheep are dead because each was wearing a radio collar, and he could pinpoint its location. He hiked out to each corpse and took field samples for a veterinarian. Sadly, one was a state-record ram, with the biggest set of horns yet found in North Dakota.
The surviving eight Alberta big horns all have collars, as do another 51 in the same area.
It’s been 14 since Wiedmann’s heard the dreaded “beep,” from any of the collars. He’s been making daily flyovers that give him a 20-mile range to tune into the collars, or driving out to the area when weather grounds the small plane.
That radio silence doesn’t mean all of the animals have avoided death. It only means that none wearing a collar has succumbed to illness.
“How many? It’s still playing out. We really won’t know until next year,” he said. Mortality could range from a low of 25 percent to as high as 95 percent. There are 350 bighorns in western North Dakota, all from relocation programs dating back to the 1950s.
Nearly all of those are in the northern Badlands. Approximately 200 are in the “hub” area that starts with the Theodore Roosevelt National Park north unit and includes the area of the Fantail and Magpie creeks and Ice Box Canyon.
Officials: Domestic sheep the cause
The most likely scenario is that a bighorn ram was in contact with domestic sheep and brought the pathogen back into the wild sheep, officials said.
“They have no resistance to the bacteria carried by domestic sheep. It’s deadly,” Wiedmann said.
He saw the 35 domestic sheep this May while flying a mule deer survey and immediately visited with the owner, since trying to isolate bighorns from the domestic sheep is a top priority.
“The owner felt terrible. He had no idea. He said they’d be loaded up that day and they were gone,” Wiedmann said.
All anyone could do at that point was hope the bighorns had dodged a bullet.
Turns out, the bullet was fired, but it took until early August, when the first mortality signals started coming in, to find its target.
“The Alberta bighorns look perfectly healthy and then they’re dead,” he said.
There’s nothing the department can do to change the course of nature; it’s all up to whether fall conditions are dry - instead of wet and humid - the stress of rut season and winter ahead, and if the disease continues to make its way from animal to animal. They know more animals are coughing, including some in the north unit.
Dan Grove, department wildlife veterinarian, said like in humans, a death from pneumonia means the animal drowns in fluid buildup in its lungs.
“It’’s pretty gruesome,” Grove said.
He said the pneumonia outbreak is the worst die-off he’s seen in the program.
There is no vaccine that works and the stress of some kind of roundup and handling to administer an antibiotic would be even harder on the animal than the sickness. He said a young ram can wander up to 15 miles to encounter domestic ewes in estrus. He said there wouldn’t be offspring, but to a ram, a sheep is a sheep.
The lack of “beeps” coming from the collars is a hopeful sign, but not a certain one.
“We’re trying to be optimistic. The mortality has slowed down, but to think this is completely over would be foolish on our part,” Grove said.
Wiedmann said the situation is not likely to affect this year’s bighorn sheep hunting season, which opens Oct. 31.
Only five licenses were issued - four by lottery and one at the Wild Sheep Association-Midwest Chapter auction that raised $70,000.
“At this point, we feel we can proceed,” he said.
Gone, not forgotten
Bighorns had all but disappeared from North Dakota’s western landscape until they were reintroduced starting in the 1950s.
Since then, Game and Fish has conducted 10 translocations, bringing in bighorns from British Columbia, Idaho, Oregon, Montana and, most recently, Alberta.
The two previous years to this one both saw record numbers of bighorns and Wiedmann said he was on his way to counting yet another record lambing when the survey was interrupted by the mortalities.
He said the entire U.S. population of bighorns is down to between 70,000 to 80,000 animals.
“This is a very highly-valued animal. Theodore Roosevelt hunted them in North Dakota and Lewis and Clark saw their first ones near the Yellowstone and Missouri rivers,” he said.
Only time will tell whether this outbreak or pneumonia is catastrophic or not.
Whatever happens, it isn’t simple to rebuild the population.
“You don’t just go the bighorn store and buy more. It’s a lot of work; the Alberta project took two years. These don’t come from Wal-Mart,” Wiedmann said.