Three consecutive winters of deep snow and brutal cold has taken a noticeable toll on North Dakota's wildlife. However, there is one species that has fared better than others - bighorn sheep.
"Of all of our big game, comparatively speaking, our bighorns are doing the best," said Brett Wiedmann, North Dakota Game and Fish Department bighorn sheep biologist in Dickinson. "After eight years of population growth we've had three tough winters. The population is down just 10 percent from 2008, so they are doing pretty well."
According to Wiedmann, cold weather has little effect on bighorn sheep. Deep snow is another issue. Because sheep have relatively short legs, deep snow can make it difficult for them to reach feeding areas and avoid predators. Too much snow can also lead to lower lamb production.
Kim Fundingsland/MDN - - Bighorn sheep prefer high elevations from which they have an excellent view of the possible approach of predators. This winter photo was taken in the North Unit of Theodore Roosevelt National Park.
"Adult survival was real good last winter, but lamb recruitment was low," Wiedmann said. "They have a tougher time surviving. We're hoping for a more typical winter this year."
North Dakota brought in additional bighorns from Montana in 2006 and 2007. Those sheep have done remarkably well, leading to the possibility that additional bands of sheep will be released into new areas capable of hosting them.
"Those sheep have changed our goals," Wiedmann said. "We still have a few areas where we could put a few sheep. We could get up to 400 or 500 sheep in the Badlands."
A set-back for bighorns was an increase in the number of mountain lions in the Badlands in recent years. Mountain lions, like the bighorns, prefer higher elevations and similar habitat. When the state implemented a mountain lion hunting season in 2005, it led to fewer lions hunting bighorns.
"Sheep habitat is great ambush habitat for lions too. That's why they live in that majestic, beautiful country," Wiedmann said. "Lions were definitely having an effect on our bighorns, but we've had no radio-marked bighorns killed by lions in the last three years. Ten years ago we had 70 percent adult survival. That last couple of years it has been 90 percent."
Wiedmann cautioned that some bighorns could still be lost to mountain lions. There's no avoiding that predator-prey relationship. However, there is a chance that some mountain lions may once again adjust their range. Mule deer are a primary food source for Badlands-dwelling mountain lions and the state's mule deer population is as low as it has been for several years. Fewer deer could cause some of the mountain lions to move elsewhere.