From this story in the Jamestown Sun:
North Dakota Game and Fish Department biologists recently completed the 2011 pronghorn population survey, which revealed the statewide population is 30 percent lower than last year. Therefore, the Game and Fish Department is recommending the pronghorn hunting season remain closed in 2011. Bruce Stillings, big game supervisor in Dickinson, said three severe winters with high adult mortality rates followed by poor fawn production has dropped the statewide population estimate to approximately 4,500 pronghorn. Until last year when the population fell to 6,500 pronghorn, the statewide population had been at or above 10,000 animals since 2003, including two years with more than 15,000.
"Our numbers are declining with few young animals observed due to poor production in 2009 and 2010," Stillings said. "To make matters worse, production this year was the lowest documented since biologists began surveying in the late 1950s." The aerial survey is flown in late June/early July after young-of-the-year are born and visible. Five airplanes covered more than 11,000 square miles of aerial transects within pronghorn habitat._