North Dakota's Bighorn Sheep Population Resilient
While two consecutive severe winters played a significant role in reducing the state's bighorn sheep population, overall numbers are still strong, according to Brett Wiedmann, big game biologist for the North Dakota Game and Fish Department in Dickinson.
A July-August survey in western North Dakota showed 289 bighorn sheep, down 20 from last year and 27 below 2008’s record summer survey. "Let's keep in mind we are comparing this year's count to record totals, so all things considered I am pleased with our current numbers," Wiedmann said.
Bighorn sheep can tolerate frigid temperatures, Wiedmann said, but it’s the deep snow that causes problems. "They struggle in deep snow because of their short legs, especially lambs," Wiedmann said. "Similar to other western big game species, bighorns could really use a mild winter this year."
Survey results revealed 94 rams, 150 ewes and 45 lambs – 231 in the northern badlands (a decrease of 11 from last year) and 58 in the southern badlands (down nine). "The encouraging news is bighorns are doing very well in the northern badlands, but continue to struggle in the south," Wiedmann said, while noting that 39 lambs were observed in the north, but only six in the south. "The northern badlands herds are carrying the population right now."
The department's survey does not include an additional 30 bighorns that inhabit the North Unit of Theodore Roosevelt National Park.
Annual bighorn sheep survey statistics are not recorded using a calendar year, but instead are done over a 12 month period beginning each April and ending the following March. Each summer, Game and Fish Department biologists count and classify all bighorns, a process that takes nearly six weeks to complete as biologists locate each bighorn herd in the badlands by tracking radio-marked animals from an airplane, and then hike into each band in order to record population demographics using a spotting scope and binoculars. Biologists then complete the annual survey by recounting lambs in March to determine lamb recruitment.
North Dakota's bighorn sheep hunting season opens Oct. 22 and continues through Nov. 4. Six licenses were issued.