Tens of millions of bison grazed the region before being nearly exterminated by hunters between 1840 and 1880.

Only about 31,000 of the animals now roam free from northern Mexico northward into Canada.

Cormack Gates of the University of Calgary, editor of the new conservation guidelines established by the scientists, says, “Bison do things in the wild that cattle can’t do in grazing systems.”

He points to depressions they make by wallowing on the ground that become habitats for other species.

The bison were once part of the food chain and served as prey for wolves and other predators.

One group already working to bring bison back to the Canadian Rockies is the Eleanor Luxton Historical Foundation, which is dedicated to Banff's nature, history and culture.

"It's the only large mammal missing from the system, and that's just plain wrong," foundation trustee Harvey Locke told Canadian Press.

Bison were also integral to the lives of native tribes. Some in the scientific team say it has been working with aboriginal communities in Alaska and the Northwest Territories to have elders explain the significance the animals once had.

Photo: File