GRAND CANYON NATIONAL PARK — Fifty-eight Kaibab Plateau bison are bound for tribal-managed herds on the Great Plains.
The National Park Service, with federal and state partners, gathered the animals from the forests and meadows near the Grand Canyon’s North Rim last week in an effort to control a herd that might otherwise damage park resources. Officials handed off the animals to the InterTribal Buffalo Council for transport to Native American lands in Oklahoma and South Dakota.
The bison, originally a captive herd from nearby House Rock Valley, have taken up residence in the relatively safe confines of a national park where hunting is prohibited and predators such as wolves are absent.
About a dozen years ago, the herd settled in and stopped migrating back to House Rock’s lower ground in winter. Park biologists say their numbers can grow by 20% a year, potentially damaging the landscape and trampling archaeological sites below the rim, where they winter.
“In national parks, while we have amazing, beautiful spaces, we have limited space,” Park Service veterinarian Danielle Buttke said. She was inspecting bison to ensure they were healthy enough for the interstate trailer trip. “What we need to do as wildlife managers is make sure that those populations don’t get so large that there isn’t any food left for the remaining animals, whether it’s bison or elk or other species.”
Emerging science from a study of the herd has produced some surprising preliminary results suggesting the bison, at current levels, may be improving the grasslands. That could influence how many of the animals Grand Canyon officials ultimately decide their range can support.
For now, the goal is set at 200. In 2017, before reductions began, the herd was thought to number at least twice that, with the potential to grow to 1,500 within a decade if left unchecked.
The departing animals are coveted additions to tribal herds that now number more than 20,000 spread among 20 states, according to Troy Heinert, the Intertribal Buffalo Council’s executive director.
“Buffalo were an Indigenous food source, and recreating that connection with buffalo takes us back to who we are as Indigenous people,” said Heinert, a member of the Rosebud Sioux Tribe. The federally chartered council includes 79 member tribes and received funding from the Bureau of Indian Affairs.
Tribes manage the animals — North America’s largest land mammal — as wildlife, he said. Some use them to supplement school lunch or elderly and diabetes diet programs, and some simply strive to maintain a cultural connection with their countries.
Heinert hired truckers to deliver bison to the Iowa and Modoc nations of Oklahoma, and the Cheyenne River Sioux in South Dakota.
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Small herd may be at the land’s limit
At the Grand Canyon, wildlife managers lure bison into an open corral by stocking it with water and hay and letting the animals come and go for a month, so they’ll return with more of their wary companions.
When enough are inside, staffers close the gate and use flags to prod them through a series of chutes, where they can be divided by sex, age or size, according to a tribe’s particular requests. They are inspected for disease using a blood draw before they are loaded on trailers.
Some are set free, because they injure themselves while ramming into each other or the corrals, or because they have particular characteristics that managers would like to retain in the herd. For instance, some elderly females are considered important for passing on information about where to graze or find water in season.
Estimated at 215 before calving produced a few dozen more this year, the Grand Canyon’s is a relatively small herd compared to the thousands of bison that roam Yellowstone. In historical terms, it’s minuscule compared to the tens of millions that roamed the continent before hunting and a government scheme to slaughter them as a means of subduing Native Americans nearly wiped them out in the 19th century.
But it may be all that the North Rim can handle, park officials say, in a zone that appears to have been on the fringes of their historic range and that may have only attracted them in wet years when the grass was plentiful.
“They never would have been here in huge numbers the way they would have been, say, in the Dakotas,” said park biologist Miranda Terwilliger, who led the operation preparing bison for transport. If they roamed Grand Canyon’s North Rim, she said, they would have done so intermittently in a world without today’s jurisdictional divides.
“And so, given the way bison management happens today, they’re not allowed to move as widely across the landscape,” Terwilliger said.
The alternative was to set a goal for limiting the herd, and the park, with the US Forest Service and Arizona Game and Fish Department, agreed on 200. That leaves enough bison for people to enjoy as they drive past meadows on the park’s north side. , and for hunters who win a state permitting lottery to stalk when some of the herd ventures onto the Kaibab National Forest.
The number is not set permanently and may evolve as the climate or other conditions change, or as science better articulates the animals’ effects on the land.
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Has bison grazing improved vegetation?
In the meadows just south of the park’s north entrance, Dana Musto is evaluating fenced, 1-acre plots inside which the grass is several inches taller than the surroundings this fall. Musto is a former park service employee who now works with the US Geological Survey and is studying the herd’s impact for her master’s thesis in ecology at Colorado State University. Although her data collection and analysis are not yet complete, she said the first year and a half of results show that areas where bison have grazed become more productive.
Even though the herd’s munching of grasses outside the fence lines is obvious in September, once they move towards the canyon rim for winter, those grasses come back thicker by spring.
It could be because of the nutrients that bison leave behind for the soil, she said, or a response by the grass plants to reallocate nutrients when disturbed.
“But we are actually seeing that areas in Grand Canyon National Park that are grazed by bison are more productive than areas that are not grazed by bison.”
Musto could not judge whether the bison may cause other issues, such as distribution of non-native plant seeds or changing grass heights that certain birds or other species may require. Those questions are beyond her study’s focus. But the bison’s foraging appears to lead to more foraging over time.
“That was a surprise — a pleasant surprise,” said Terwilliger, the park biologist. The study could alter future designations of how many bison the Kaibab Plateau can support inside and outside the park.
“This is really important information for managers both on the forest and on the park (for) determining that carrying capacity,” Terwilliger said.
Hunters help cull the herd, at a price
Beyond grass production, bison can affect springs that are important water sources for wildlife and plants. The Kaibab National Forest had to fence some of its springs to protect them, North Kaibab District Ranger Todd Russell said.
“The herd reduction seems to have made a big difference,” he said.
Since the park began capturing and removing bison in 2018, it has sent 182 to eight tribes. Last year the park tried a limited lethal removal that killed six. That program used hunters that the park termed “skilled volunteers” in an effort not just to reduce the herd, Terwilliger said, but to make the park less inviting so some of the herd would wander elsewhere. In all, wildlife managers have removed 203 bison over five years.
Beyond the park, the Arizona Game and Fish Department manages bison as game animals. The state sold 111 bison permits by lottery this year, split between a spring hunt targeting mostly bulls and a fall hunt aimed at cows. Hunters took 40 bison on national forest lands last year, Regional Supervisor Larry Phoenix said, roughly equaling the number removed from park lands by volunteer killings and relocations.
The state’s bison permits are expensive. The chance at an adult bull, the most expensive, costs $1,113 for resident hunters and $5,415 for non-residents. Cow and yearling tags cost hundreds less for residents, and thousands less for non-residents. The state supports the goal of 200 bison and believes it will maintain the ability to conduct a hunt, Phoenix said. The number of permits has declined with the herd reductions.
“There is no way that just one of the agencies could manage this herd of bison because of the way that they move across the (park) line,” Phoenix said. “And so, because of the collaboration, the bison are a much healthier herd.”
Grand Canyon: Bison at the North Rim won’t be hunted this fall
When bison return, other wildlife follow
The herd has taken on characteristics that may be better prepared for a warmer climate than others around the nation, Buttke said. For one thing, they’ve grown somewhat smaller than most bison.
“The thing that’s really unique about this population is that they have adapted so well to this landscape, the heat, the aridity or lack of precipitation and moisture, that they are probably one of the best-adapted herds to withstand some of the changes we expect with climate change.”
In coming years, the park service and partners will decide whether to modify the 200-bison goal, or to try other control methods such as contraception. Although the herd’s ultimate fate is not decided, Terwilliger said she expects they’re here to stay.
“People love seeing them,” she said. “Bison have a very unique spot, I would say, in the heart of Americans. That’s part of why they’re the national mammal.”
Perhaps none are so enthusiastic as tribes who return the animals to their lands. Heinert has delivered thousands of bison from public or private herds to his council’s member tribes, and said they often conduct ceremonies for the occasion. It can be emotional, he said, but it’s also ecologically significant.
“Buffalo is a keystone species,” he said. “When you restore buffalo back, you’re restoring your land, and other wildlife soon follow.”
Brandon Loomis covers environmental and climate issues for The Arizona Republic and azcentral.com. Reach him at email@example.com or follow him on Twitter @brandonloomis.
Environmental coverage on azcentral.com and in The Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust. Follow The Republic environmental reporting team at environment.azcentral.com and @azcenvironment on Facebook, Twitter and Instagram.
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