Bison hunters took advantage of higher than usual bison numbers on the National Elk Refuge, harvesting a record number of animals in the season’s first 48 hours.

Thirty-four bison, including eight bulls, 25 cows and one calf, were reported killed to the Wyoming Game and Fish Department between Wednesday and Friday. The numbers could rise as more kills trickle in, said Tim Fuchs, Jackson Region wildlife supervisor.

“We had a very good day,” Fuchs said. “Last year, we only took 19 on the opening day.”

From 2007 to 2011, hunters took an average of just 11 animals on opening day. In 2010, the take was a lone bull. The hunt is the primary tool for wildlife managers seeking to reduce the number of bison in Jackson Hole.

Hunting on the refuge didn’t start until 2007, when the U.S. Fish and Wildlife Service and the National Park Service completed a Bison and Elk Management Plan. The 2007 plan required the agencies to whittle the numbers down from the 1,200 bison counted then to about 500. Five years in, wildlife managers are mostly on pace — an aerial survey counted 910 bison last winter.

That the reproductive part of the herd — cows and calves — isn’t as accessible to hunters as the bulls tends to limit the success of the hunt, Fuchs said. Bison have a “very high reproductive rate” and “low natural mortality across the board,” which also makes it difficult, he said.

To boost the take, Game and Fish authorizes an on-again, off-again season that runs from this past Wednesday to Jan. 6 on the refuge and surrounding Bridger-Teton National Forest lands. The stop-and-start format, which has 11 periods, tricks the bison into moving off Grand Teton National Park, which is a hunt-free zone.

The unique approach has had mixed success, Fuchs said.

“We are seeing some pulses with that,” he said. “Things settle down, they come back up. We’ve been able to have some success.”

Game and Fish issued 410 of the once-in-a-lifetime bison permits this year. Of those, 300 licenses are for cows or calves, and another 110 are “either-sex” tags that allow hunters to take bulls.

Hunter success rates tend to be high. Last year, 227 hunters took 101 bulls, 86 cows and seven calves, a success rate of 85 percent.