The bighorn sheep population in the western North Dakota Badlands grew by 8 percent, according to a survey recently completed by the North Dakota Game and Fish Department.
Big game biologist Brett Wiedmann, who works out of the department’s Dickinson office, said the results are positive after the bighorn’s all-age die-off from bacterial pneumonia in 2014.
“To see an increase the year after the die-off began is a step in the right direction,” he said.
Wiedmann wrapped up the department’s count earlier this month. Game and Fish biologists count and classify all bighorn sheep in late summer and then recount lambs the following March, as they approach one year of age, to determine recruitment, according to a news release.
The survey revealed 292 bighorn sheep, a count that included 88 rams, 160 ewes and 44 lambs. Wiedmann said 76 percent of lambs survived the winter, an encouraging number.
The count is also a 3 percent increase from the state’s five-year average.
Thirty bighorns believed to be in the North Unit of Theodore Roosevelt National Park weren’t included in the count, and is a number that Wiedmann called an estimate.
A bighorn sheep hunting season is tentatively scheduled to open later this year, but only if there isn’t a recurrence of bacterial pneumonia. The season’s status will be determined Sept. 1, after summer population surveys are completed.
“As it stands right now, we’re pretty confident we’re not losing many adults at this point, so we expect to have a season,” Wiedmann said.
Wiedmann said the pneumonia virus can persist in a bighorn sheep herd for decades.
“We’re by no means out of the woods,” he said.
The northern Badlands population, which was hit the hardest by the die-off, increased 13 percent from last year, according to survey figures. However, the southern Badlands population was down 19 percent.
Adult mortality rates among the bighorns “slowed significantly” last year, and the lamb survival rate compensated for the adult losses of 2014.
“The bad news is that many bighorns are still showing signs of pneumonia, so next year’s survey will be important in determining if the state’s population is continuing to recover from the disease outbreak, or if the pathogens are likely to persist and cause a long-term population decline,” Wiedmann said in a statement.
Dr. Dan Grove, a Game and Fish veterinarian, said disease testing last winter revealed that pneumonia pathogens were present in 16 of 22 bighorns tested.