Home on the Range?

On any given summer day, visitors driving past the North Rim entrance to Grand Canyon National Park may spot bison grazing peacefully by the side of the road. The subalpine meadows and forests of quaking aspen, Engelmann spruce and Douglas fir on the Kaibab Plateau are more reminiscent of Yellowstone than the Grand Canyon’s desert scrub, and the bison look perfectly at home.

Conservationists don’t see it that way. They argue that the bison don’t belong in the park, where the animals overgraze meadows, contaminate water sources and trample archaeological sites. Left alone, the herd of more than 600 — no one knows exactly how many — could more than double over the next decade.

“I’m concerned we don’t have a handle on the impacts,” said Roger Clark, a program director at Grand Canyon Trust, a nonprofit dedicated to protecting the Grand Canyon and the Colorado Plateau. “It’s a problem that’s bad that’s going to get worse.”

Before bison were nearly hunted to extinction in the 19th century, they occupied a wide range of ecosystems from Canada to northern Mexico. Some stories from tribes in northern Arizona mention bison, but there is no definitive evidence that the animals historically lived in the Grand Canyon.

The origin of today’s herd is much clearer. In 1906, a frontiersman named Charles Jones assembled a herd of bison captured in places from Manitoba to Texas and attempted to breed them with Galloway cattle. This type of experimentation was common at the time, and these days, many bison contain some cattle DNA. Jones struggled to build a profitable enterprise, though, and he gave up after a few years. He sold some of the animals, but about 20 were pretty much left to their own devices in House Rock Valley near the North Rim of the Grand Canyon. By the time the state of Arizona purchased the herd in 1927, it had grown to 98 bison.

For decades, the herd stayed in the valley, and the Arizona Game and Fish Department managed the population through roundups and controlled hunting. That changed in the late 1990s, when wildfires opened up a path to the Grand Canyon, and greater hunting pressure caused a few animals to leave. Others followed, and by 2009, the bison had stopped going back to House Rock Valley. Now they spend most of their time in the national park, where they’re safe from hunters.

The bison have thrived in their new homes, but they’ve not been very considerate residents. The area has a high density of Native American archaeological sites, and park staff have documented broken artifacts and damage to prehistoric structures they attribute to the bison. They also suspect the animals are responsible for E. coli bacteria they’ve detected in water, and the bison’s overgrazing has paved the way for exotic plants to take root and placed rare native plants at risk. Martha Hahn, the park’s former science and resource management division chief, said the endemic plants “didn’t evolve with that kind of grazing. You’re going to see some species blink out.”

Several years ago, park staff decided to take action and used food pellets containing molasses to round up a small number of bison. It worked so well, the animals started chasing the truck with the feed when they saw it coming. “We said it was like crack, but the Game and Fish didn’t like that term, so we called it cake,” Hahn said. The corralled bison were trucked back to House Rock Valley, but once the gate there was opened, they were back in the park within 24 hours, she said.

Exactly what to do with the animals some derisively call cattalo or beefalo hinges on what they actually are. The Park Service used to consider them non-native hybrids, but the agency has since reversed its position. In 2014, the Department of the Interior charted a course for restoring bison on “appropriate landscapes” within their historical range, and in a 2016 report, the Park Service declared them native to the park. Critics of the report said it was based largely on circumstantial evidence and were not convinced by the report’s conclusion. “It’s an introduced hybrid species — and decidedly not native,” said NPCA’s Kevin Dahl, who supports removing every bison from the park. “They’re damaging an area where the introduction of even native bison would be a problem.”

The animal’s change in status meant that instead of eradicating undesirable intruders, the Park Service was charged with maintaining a viable bison population on the plateau. Park managers considered many options to reduce the size of the herd, including fertility control, the reintroduction of wolves and the use of dogs to herd bison, but they rejected them as ineffective or inappropriate. Instead, they opted for a plan to capture and transport bison to areas managed by tribes, state and federal agencies, and other willing recipients. They also decided to recruit volunteers and tribal members to cull the herd.

Arizona wildlife managers frown on the proposed use of volunteers rather than recreational hunters, but they support the idea of maintaining a herd in the area, in part because the animals that wander outside the park boundaries can be hunted. “These animals represent tremendous value to the citizens in Arizona in the form of hunting and wildlife viewing,” said Jim Zieler, chairman of the Arizona Game and Fish Commission.

Two years after the release of the plan, the removal effort has yet to start in earnest. A pilot corralling project scheduled for last fall was scuttled because early snow had caused the bison to move to less accessible areas. A change of park superintendent, chronic understaffing and a government shutdown over the winter have not helped. Now park staff are hoping to begin anew in September.

Jan Balsom, the park’s senior adviser on stewardship and tribal programs, said that if all goes well, bison will be captured and “driven to happy homes.” The overall goal is to reduce the herd to fewer than 200 animals, but how many bison are left in the park after the three-to-five-year removal efforts is anyone’s guess.

“We don’t have any illusions about our success,” Balsom said. “It will take a while to get to a point where they’re not damaging the resources.”