Nearly a hundred wood bison roaming free in the area of the Lower Innoko and Yukon rivers are adjusting after being released into the wild last month, according to the Alaska Department of Fish and Game.
The agency said Tuesday that the animals' eating, roaming and herding habits are what they should be for wood bison in the wild.
The animals were flown to Western Alaska in early April from the Alaska Wildlife Conservation Center. Before their reintroduction, the species had been extinct in Alaska for more than a century.
Cathie Harms, Fish and Game's regional program manager with the Division of Wildlife Conservation, said that the day after their release some of the bison wandered as far as 10 miles away and were soon wary of humans.
"Biologists on foot and on snowmobile encountered bison within the first week and the bison reacted by being alert, then moving away, as wild animals do," Fish and Game wrote in a statement Tuesday.
A little more than a month after their release, the herd's population is already fluctuating.
At least six calves have been born since the herd's arrival, and more are expected. Twenty-five pregnant cows were released last month. A herd will anchor in the area where the calves are born, Harms added.
Fourteen wood bison have died so far. Five died of undetermined causes, which Harms said are being investigated, and nine others drowned after falling through degrading river ice.
The death of some wood bison was expected and shouldn't harm the herd's overall chance of success, Fish and Game said in the release. Harms said none of the animals' deaths appeared to have been caused by predators or humans, and breakup is a deadly time for many animal populations.
"There are always concerns," Harms said. "We've had situations where we've lost dozens of musk ox from one group through ice. You can't guarantee anything."
The wood bison are eating well, Harms said. At the conservation center, the animals ate hay with a nutritional supplement. Since they've arrived in their new home, the bison have been chowing down on a diet of sedges and grasses. Harms said what they're eating now is much richer in protein.
"We actually put hay into the temporary holding pen we initially released them in, but out of the 100 we brought only about 20 ate it," she said.
At the end of May, bulls from the conservation center will be moved from their current home, just south of Anchorage, to Western Alaska. Harms said they need to be delivered in time for breeding season.
"(Bulls) won't actually interact until breeding season," she said. "... It's a matriarchal society; groups of bison are lead by cows. The calves, cows stay in groups. The bulls will stay away until its time to breed, then they'll leave. They aren't very social creatures."