For the first time in more than a century, wood bison calves are being bred and born in the Alaska wilderness.

Wildlife biologists have spotted calves born to animals that were released to the wild last summer.

State officials had been raising the bison, obtained from Alberta's Elk Island National Park, in captivity near Anchorage. 130 were then flown to a remote location roughly 450 kilometres away.

"We had many fears of what might happen," said Tom Seaton, who runs the state's wood bison program.

"Like any reintroduction, there's always a chance it could fail."

Seaton's biggest concern was that the animals would disperse and not find each other during mating season. However, most of the bison remained within a 45-kilometre radius, and nature took its course.

"We're forever indebted to Canada for saving the wood bison and restoring the sub-species to a point where it can be reintroduced to Alaska," Seaton said.

"We really owe Canada a lot."