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Know the West

Bison roundup at Rocky Mountain Arsenal refuge

At least 20 animals were removed from the herd to let habitat recover.


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The bison herd at Rocky Mountain Arsenal National Wildlife Refuge, 16,000 acres crammed between Denver, Colo., and a major airport, is growing fast. Last week, about 45 biologists and wildlife and land managers from across the country gathered for a semi-annual round-up to look for disease, monitor genetic diversity and move some animals to keep the size of the herd, now in its seventh year, in check. About a quarter of the herd has to be relocated because the 2,500 acres of recently restored short grass prairie habitat where it lives can’t take such heavy use quite yet.

“They got there faster than we expected,” the refuge manager, David Lucas, said of the herd’s growth from a couple dozen to 87 animals. Lucas oversaw the event, opening chute gates and driving a truck to round up the bison. He hopes to expand their habitat by several thousand acres, once more of the refuge’s land has been restored. Native species are still on their way back after decades of agricultural and military and industrial use. Lucas anticipates that, in the long-term, as many as 200 of the wooly creatures could roam the area, visible from suburban backyards and the airport boulevard.

Bozeman-based U.S. Fish and Wildlife Service biologist Lee Jones, who helps with most of the agency’s bison roundups at six refuges across the country, was also at the Arsenal last Tuesday. She drew blood, embedded microchips the size of rice grains, scanned existing ones to bring up health records on a hand-held data system and pulled hairs for genetic tests. The goal is to keep the herds on each refuge diverse to avoid inbreeding-associated problems, said Jones, who built this herd from others back in 2007. “Based on genetics, we decide where (removed bison) can be sent and which genetics we want to keep here.”

Of the 20 or so bison being removed over the next month or two, three will go to Sully’s Hill National Game Reserve in North Dakota, two to Neal Smith National Wildlife Refuge in Iowa, and a couple to Colorado State University for educational purposes. The fate of the others has yet to be decided; some may go to private ranches and eventually be killed for meat.

The Arsenal originally housed facilities that manufactured chemical weapons for both World War II and the Cold War. For several decades, Shell Chemical produced the pesticide DDT there, polluting the soil and groundwater. A population of wintering bald eagles discovered in the ’80s sparked the beginning of environmental restoration of the site, and in 1992 it was designated a national wildlife refuge. Now it’s home to prairie dogs, deer and coyotes, in addition to the bison herd. The Arsenal refuge, like Rocky Flats, a former nuclear-weapons plant on the opposite side of Denver, is one of several former military or industrial sites in the West that have been reborn as wildlife refuges.

Although such transformations are encouraging, these sites are often close to cities, which means wildlife can’t just roam free. The Arsenal refuge is hemmed in by the Denver suburb, Commerce City to the southwest, multi-lane Peña Boulevard that serves Denver International Airport to the east, and major highways in every other direction. An eight-foot, heavy gauge wire fence and a second, slightly shorter fence ensure that bison can’t wander into nearby towns or roadways. “I can’t just put a three-strand barbed wire up, and if one gets out, go catch it,” Lucas said.

Visitation has grown quickly alongside the bison herd, from 23,000 onlookers last year to more than 300,000 in 2013. Local officials say the tourism benefits the Denver area’s economy. Mayor Michael Hancock called the refuge “a great example of how the metro area balances being the fastest-growing region in the United States and protecting our natural resources like the bison.”

As of a few days ago, Jones had one last roundup to complete before the end of the year, in Oklahoma. The refuges have an important role to play in helping urban residents connect with wilderness, she said. “Most people only get to see bison on TV, but the Arsenal is looking for the public to come and observe the roundup operation.” Events like last week’s roundup are a way for people to understand what goes into managing a wildlife refuge and a growing bison herd. “It’s important that people understand the value of that (management),” Jones said, “if we’re looking at preserving bison in future years.”

Tay Wiles is the online editor of High Country News. She tweets @taywiles. Theo Stroomer is an independent photographer and a contributor to High Country News.