BANFF, Alta. -- Parks Canada says wild plains bison that were reintroduced to Banff National Park are now free-roaming animals.

Officials say 31 bison were released Sunday into a 1,200 square-kilometre zone that features meadows and grassy valleys for grazing along the park's eastern slopes.

"Now, they are free-roaming wild bison and their path forward may not be easy," said Bill Hunt, manager of resource conservation with Banff National Park.

"They will experience harsh winters, they will travel through difficult terrain and they will eventually be hunted by wolves and other predators."

He said they will also play an important role in keeping the ecosystem healthy in the national park.

"Bison are what we call a keystone species -- that means bison alter the food web and the landscapes."

As examples, he said they improve grazing for animals such as elk because they fertilize the grasses, open forests for meadow-loving birds and small mammals, create amphibian habitat by wallowing in the lowlands and their heavy winter coats shed each spring to provide nesting material for alpine birds.

Hunt said they are also an important food source for scavengers and predators such as wolverines and grizzly bears.

"Bison will make Banff a wilder place," he said.

Plains bison are an iconic part of Canada's history, having freely roamed in the Rockies, filling an important need for the livelihoods of First Nations people and early settlers.

They disappeared from the area due to overhunting before the national park was created in 1885.

Sixteen plains bison from Elk Island National Park were reintroduced as part of a $6.4-million plan in February 2017 into the remote Panther River Valley, about 40 kilometres north of Banff.

Ten of the females had calves last year and five of those animals gave birth again this year.

The reintroduction is supported by First Nations and conservationists, but concerns have been raised by some nearby landowners about the animals wandering out of the park.

Parks Canada said it will keep a close eye on the herd through electronic monitoring and wildlife staff on the ground will try to keep them in the area.

"We have this gift of natural containment -- rock ridges and cliffs that typify the mountain environment," said Karsten Heuer, project manager for the bison reintroduction.

"But there were these key pinch points on the periphery of the 1,200 square-kilometre reintroduction zone, in which the bison are now free roaming, that we wanted to potentially be able to deflect the bison if they came to those areas."

They've also installed fencing at some of those pinch points to keep the bison from wandering out of the park.

If they do get on to provincial land, Alberta Environment and Parks said the herd will soon be protected under a special ministerial order.

"People are concerned about if they do get out of the park," said Minister Shannon Phillips. "Of course, there is monitoring and response in place if that happens.

"If it does, we have taken steps in the past ... to protect the Ronald Lake bison herd and I will do that again with this particular herd."

The order would give the bison the same protections as animals such as grizzly bears.

"You can't just shoot 'em if you want to," said Phillips.

The province said the order will be in place next week.