North Dakota's Bighorn Sheep Population Holding Steady
The North Dakota Game and Fish Department’s annual bighorn sheep survey revealed a minimum of 283 sheep in western North Dakota, unchanged from last year and only 3 percent below the five-year average.
In total, biologists counted 86 rams, 158 ewes and 39 lambs. Not included are approximately 30 bighorn sheep in the North Unit of Theodore Roosevelt National Park.
Brett Wiedmann, big game biologist, said the northern badlands population remained stable and southern badlands herds stabilized following several years of declining numbers.
“Despite ewes enduring a brutal winter in 2010-11, lamb recruitment increased to 28 percent, which is about average in North Dakota,” Wiedmann said. “Also, 83 percent of the lambs counted last summer survived the winter.”
Game and Fish Department biologists count and classify all bighorns in late summer and then recount lambs in March to determine recruitment.
After three consecutive severe winters, mild conditions experienced this winter were needed, Wiedmann said. “We monitored 71 radio-marked bighorns last winter and didn’t have a single mortality,” he added. “Although spring lamb production was low in 2011 due to the severity of last year’s winter, lamb survival through this past winter was exceptional. Adult ewes couldn’t be in better condition right now so we expect a bumper crop of healthy lambs to begin hitting the ground within a couple of weeks.”
Although most news was encouraging, Wiedmann was concerned with a 10 percent decline in the ram count from 2010, and continued low population levels coupled with poor lamb recruitment in the southern badlands, where only two were observed. The ram-to-ewe ratio declined to 54 rams per 100 ewes.
“Overall, we’re quite pleased with the results of this year’s survey,” Wiedmann said. “Following three epic winters our bighorn sheep population is only 10 percent below our record count in 2008. Comparatively speaking, it appears our bighorns handled the recent harsh winters much better than our mule deer and pronghorn populations.”
Four bighorn sheep licenses were issued in 2012, two fewer than 2011.