Last Friday, four bison waited quietly inside a grey trailer parked on the plains of South Dakota’s Badlands National Park. When the doors of the trailer swung open, the hulking animals darted out and galloped across the snow-covered, windswept landscape—the first inhabitants of territory that has not been occupied by bison since the 1870s.
As Seth Tupper of the Rapid City Journal explains, staff released the bison as part of an effort to expand the animals’ range in the national park, which encompasses a stretch of dramatic rock formations, canyons and grasslands on the edge of the Great Plains in South Dakota. Bison have long roamed the rugged, western part of the park, but a parcel of privately owned land blocked their migration into the central area of the park’s North Unit, where most visitors spend their time.
In 2014, with support from the U.S. Forest Service and non-profit groups like the World Wildlife Fund, the park secured a land swap with the Don Kelly Ranch, which owned the key piece of territory, thus opening the land up to bison migration. The agreement expanded the animals’ range by 22,000 acres, bringing it up to a total of more than 80,000 acres, or “an area more than one-and-a-half times the size of Manhattan Island,” as the WWF points out.
Before bison could be released into the new landscape, measures had to be taken to ensure that the animals do not mingle with livestock on nearby ranches. According to Tupper, the park spent $1.218 million on 43 miles of new fencing and three cattle guards; $743,000 came from charitable organizations and their supporters.
Millions of America’s national mammal once thundered across the continent. But due to extreme overhunting by European settlers, bison were pushed to the brink of extinction; by the late 1800s, only 1,000 remained.
Today, around 31,000 bison are being managed as part of conservation efforts, and though they are classified as “near threatened,” their population is considered stable. But according to Defenders of Wildlife, bison are still “ecologically extinct” in much of their historic range, “except for a few national parks and other small wildlife areas.”
The Badlands National Park launched its conservation efforts in the 1960s, when 50 bison were reintroduced to the park. Today, around 1,200 bison live there, and officials hope that some will migrate into their newly expanded territory on their own. By restoring the animals to an area that they last occupied some 150 years ago, park officials hope to bolster Great Plains habitats, where bison play a crucial role. They munch constantly on native grasses, which creates areas for prairie dog colonies, and his in turn draws prairie dogs’ natural predators: coyotes, large birds of prey, endangered black-footed ferrets.
“By ensuring that the largest of creatures are thriving,” the National Park Foundation explains, “the park can more safely guarantee the health of the entire ecosystem.”