Drive to northeastern Commerce City in the near future and you may see bison out your back window.
The Rocky Mountain Arsenal National Wildlife Refuge will expand its bison area to 10,300 acres from 6,500 in the next year, so for those living by the northeastern part of the refuge, bison will “basically be in your backyard,” wildlife refuge specialist Tom Ronning said.
Though some might like the idea of seeing the arsenal’s herd of 250 bison roaming the high plains near Denver International Airport, the refuge’s goal is not to increase sightings of the animals, but to improve the health of the remaining patch of prairie in the city.
On Wednesday, officials from the refuge and the U.S. Fish and Wildlife Service shared progress and plans for $2.6 million in Inflation Reduction Act and Bipartisan Infrastructure Law funds to manage bison and grasslands resiliency in the refuge.
The expansion is part of the Grasslands Keystone Initiative to conserve the Great Plains, which have lost more than 50 million acres of grasslands in the past 10 years. The arsenal, which stretches northeast from the Montbello neighborhood of Denver to Reunion in Commerce City, is about 15,000 acres of short- and mixed-grass prairie where perhaps 330 species live, including the bison.
Deputy refuge manager Megan Klosterman calls bison “ecosystem engineers,” and says allowing them to roam more freely across the refuge will help native plants grow better and increase species diversity in the grasslands ecosystem.
They evolved with the native plants, so their feeding on vegetation actually helps it grow back stronger, U.S. Fish and Wildlife Service deputy director Siva Sundaresan said. The weight of their footsteps (males can weigh up to 2,000 pounds, females 1,000) mixes nutrients in the soil, and their hoofprints create wet microclimates for new plants to grow.
Though the bison will have more space, they won’t disturb human activity, Ronning said. Much of the refuge’s funding from the Inflation Reduction Act will go toward building 4.25 miles of fencing and cattle guards around the bison area. Visitors will be able to safely drive through the refuge or walk the trails around its edge.
Refuge officials estimate 250 bison in their herd, including around 40 calves, and they plan to maintain a similar number when the space expands.
The bison fences will be up within a year, and Ronning estimates they will cost “a couple hundred thousand dollars.” Other Inflation Reduction Act funds will go to building wells around the reserve so bison have additional water sources. Refuge officials said they have already allocated all the funds to projects but declined to give further details or cost estimates.
While the reserve makes space above ground for North America’s largest mammal, they’re releasing one of the most endangered mammals below ground. Refuge officials added 19 more black-footed ferrets into the reserve Wednesday, bringing the total number to about 30, deputy refuge supervisor Nick Kaczor said. Once thought extinct, there are now more than 400 black-footed ferrets in the wild.
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This is the refuge’s first ferret release since 2020, when sylvatic plague wiped out most of their population, Kazcor said. He hopes the kits born this year integrate into the prairie dog burrows and reproduce to keep bringing their numbers up. They’ll contribute to species diversity and keep the prairie dog population in check.
To protect the land and animals from increased wildfire threat, the refuge has received $165,000 through the Bipartisan Infrastructure Law to improve grassland resiliency. They used these funds to hire a team of American Conservation Experience interns this summer, who cleared dead trees and invasive plants that add fuel to wildfires and built fencing to protect native vegetation for over 2,000 acres of land.
Current projects will prepare the reserve for the effects of drought and lean water years in the future, Klosterman said.
“We’re getting ahead of climate change,” she said.