Parks Canada has reintroduced a herd of plains bison to the country's oldest national park in Banff, Alberta, more than 130 years after the iconic North American animal last grazed the eastern slopes of the Canadian Rockies.

Bison, Canada
A wild bison that has been selected from Elk Island National Park Johane Janelle/Parks Canada/Reuters

The conservation team moved 16 bison from a protected herd in central Alberta into an enclosed pasture in Banff National Park, in the west of the province last week. The herd will stay under observation in the remote Panther Valley until summer 2018, when the animals will be released into the full 460-square-miles (1,189-sq km) reintroduction zone in the park's eastern valleys.

Parks Canada told Reuters that bison were once dominant grazers and that bringing them back would restore their missing role in Banff's ecosystem. "This would be one of only four plains bison herds in North America that would be fully interacting with their predators and shaping the ecosystem as they did over a hundred years ago," said Kasper Heuer, the bison reintroduction project manager. Those predators will include wolves and bears native to the park.

Ten pregnant female bison and six young bulls were tested for disease and radio-collared before being herded into five shipping containers and driven 250 miles (400km) across Alberta by truck. The conservation team taped rubber hoses to their horns to prevent the animals injuring each other while in transit.

Since the Panther Valley is not accessible by road, officials attached the shipping containers by long line to a helicopter and flew them in one at a time for the last 16 miles (25km).

Vast bison herds of up to 30 million animals once migrated freely across North America. The animal was nearly hunted to extinction, and rangers estimate bison have not grazed in Banff National Park since before it was established in 1885. Bison have great spiritual meaning for North America's aboriginal groups, having once provided an important source of food, clothing and shelter.

The reintroduction also coincides with the 150th anniversary of Canada's 1867 confederation into a federal union.