The Rocky Mountain Arsenal National Wildlife Refuge is bustling with new life as bison calves, deer fawns and various bird species are born in the spring and early summer. These young creatures have arrived at one of the country’s largest urban wildlife animal refuges near Denver. However, as they begin their lives in this protected habitat, they face an increasingly formidable challenge: climate change.
“Bison calves and waterfowl nestlings begin to arrive around May, and deer fawns are often first seen in early June,” said Jan Fore, Public Affairs Specialist for the Refuge. “If visitors look carefully, they may also see young prairie dog pups, burrowing owl chicks, red-tailed hawk, eagle fledglings, or coyote pups.”Â
The 15,000-acre area in Commerce City, has undergone a remarkable journey from Native American hunting grounds to farmland, then a WWII weapons arsenal, and eventually a wildlife sanctuary. In 2010, after an extensive clean-up effort, the U.S. Army handed the land over to the U.S. Fish and Wildlife Service, which has since managed it as an animal refuge for over 330 species, including the iconic American bison and the endangered black-footed ferret.
These animals are growing up in what seems like an idyllic environment, but the reality is that the Refuge, like many natural habitats, is threatened by climate change. According to the Colorado Water Conservation Board, the state has warmed by +2.3°F between 1980 and 2022, with projections for even more severe changes in the coming decades. These rising temperatures bring about shifts in snowmelt runoff, stress on ecosystems, and more frequent extreme weather events—all of which could disrupt the lives of the Refuge’s inhabitants.Â
The animal sanctuary is already experiencing the impacts of this warming trend. Higher temperatures and reduced afternoon rains have led to a lack of cooling relief for animals. The rising heat and less shade place additional stress on young wildlife, particularly for species like bison calves and deer fawns, which are more vulnerable to these conditions. These factors can lead to dehydration, increased mortality rates among young animals, and changes in the availability of food sources, which can impact growth and survival rates.
“I have been going to the conservation for quite some time, and you can definitely see a difference with all this heat,” said Brenda Jean, an animal conservationist and a native of Colorado. “It’s not that the animals are not there anymore or look like they are having a bad time. I would just say that you can tell when it’s a hot day because all the animals are hiding, and it seems like we have gotten more of those days recently, I guess.”
The U.S. Fish and Wildlife Service has implemented several measures within the Refuge to combat these effects. Prescribed burns, for example, are used to manage prairie vegetation, reduce wildfire risks, and sustain wildlife habitats. These efforts are critical to ensuring the space remains a safe haven for both the new and existing species.
In addition to these efforts, the animal refuge is also focused on helping species adjust to the impacts of climate change through adaptation and mitigation strategies. This includes building structures to defend against flooding, relocating species at high risk of being lost, and adjusting land management practices to suit the changing conditions.
Mitigation efforts focus on reducing heat-trapping air pollution, stabilizing greenhouse gas levels, and restoring degraded ecosystems to reduce the overall carbon footprint. Still, as these young animals gain independence, they must learn to navigate a rapidly changing world.
“Bison calves are shedding their red fur, replaced with the familiar brown coat seen on adult bison,” Fore said. “Deer fawns are losing their spots, and the birds of prey are leaving their nests.”
Despite the challenges posed by climate change, the animal refuge near Denver remains a vital space for both wildlife and people. Visitors can explore 20 miles of hiking and biking trails, fish at Lake Mary and Lake Lador, and participate in educational events highlighting conservation’s importance in a rapidly changing world.
“The best view of wildlife is from a distance,” Fore said. “Remember to respect all wildlife and give animals plenty of space.”
While approaching or even handling young animals might be tempting, it’s important to let nature take its course. “Mothers often leave newborns alone while they go off to feed, causing concern that the baby animal was orphaned,” Fore said. “It’s likely that Mom is close by or will return soon.”
The new baby animals at the Refuge bring joy and serve as a reminder of nature’s resilience. Yet, as climate change reshapes their environment, their future is increasingly at risk. The Refuge is not just a sanctuary for these animals—it is a critical stronghold in the effort to protect their future against growing environmental challenges.
