Too many moose on the loose?
GRAND LAKE, Colo. — Before the Colorado Division of Wildlife introduced moose into the state in 1978, it was rare to see the species. Moose would occasionally wander into Colorado from Wyoming, but there were no sustained populations.
Today, roughly 3,500 moose live in the state’s mountainous areas, occasionally traveling as far east as Greeley.
“I wouldn’t have predicted that they would have done as well in Colorado as they have,” Will Deacey, large mammal ecologist at Rocky Mountain National Park, said.
The national park is home to at least 240 moose according to an aerial survey scientists conducted last summer. It’s difficult for scientists to determine how many moose the park can support, since conditions change year to year, Deacey said.
But the species’ rapid growth and voracious appetite is harming wetlands in Rocky Mountain National Park. In the park’s Kawuneeche Valley, for example, 98% of willows have disappeared since 1999.
Other factors, like a shrinking beaver population and human development, can also contribute to loss of wetlands, but moose have quickly become one of the park’s top management priorities.
Moose, which usually weigh 800 to 1,200 pounds, eat up to 60 pounds of vegetation per day. Over the course of a summer, a single moose consumes about as much willow as 15 elk.
Wetlands make up just four percent of the park’s area, but they are a hotbed for biodiversity. Sixty-five percent of the park’s rare plant species live in wetlands. Riparian areas also act as a natural firebreak, slowing the spread of wildfires and providing an oasis for animals to survive burns, Deacey said.
“While moose are loved by many visitors, their increased numbers are making it infeasible to protect and restore these sensitive areas,” Gary Ingram, park superintendent, said in a December 2025 webinar.
Outside of the park boundary, wildlife managers have more tools at their disposal to manage species numbers, namely hunting.
Colorado Parks and Wildlife issued 670 tags to hunt moose in 2025. In 2024, hunters harvested 501 moose in the state. But hunting is prohibited in Rocky Mountain National Park.
GPS data from collars scientists have attached to moose show that the animals leave the park less often during hunting season, said Deacy, but it’s unclear why.
Biologists employed sharp shooters as recently as 2008 to cull the park’s elk population, but the approach drew backlash from environmental groups, who wanted the park to introduce gray wolves to manage the elk population.
Since Colorado Parks and Wildlife reintroduced wolves to the state in December 2023, wolves have passed through the national park, but haven’t settled there, Deacey said.
“Wolves tend not to eat very many moose, and the reason is thought to be that they're just more difficult prey — they're larger, they're more dangerous for wolves. And so if they have other choices, like elk and mule deer, then they tend to pass on moose,” Deacey said.
But other environmental groups have continued to argue that gray wolves are the best management tactic.
In a statement to the Colorado Springs Gazette published in December, the conservation group Defenders of Wildlife wrote, “To the extent that Rocky Mountain National Park has issues with herbivores overbrowsing willows, young aspens, etc., that’s a ‘lack of native predators’ problem. And that problem has an obvious and natural solution — allow Colorado’s gray wolf population to recover.”
The disappearance of wolves and grizzly bears caused by hunting is one of the reasons there’s now an “unsustainable number of ungulates," said Deacey, but it’s not always possible “to turn back time, reset these systems and make them whole again.”
Elsewhere, land managers have turned to beavers, which build dams and slow the flow of water, to help them restore wetlands.
Rocky Mountain National Park was once home to thousands of beavers, but at this point, the park may not have enough food resources for new beaver populations to survive, Deacey said.
In the meantime, aerial photographs from this summer provide evidence that work by park staff and environmental advocates is helping to restore wetlands in the Kawuneeche Valley. Volunteers constructed dozens of stream obstructions that mimic beaver dams and help to hold water in the meadow.
Park scientists are currently reviewing feedback from members of the public. Any changes to the wetland or moose management plans will require review by the National Environmental Policy Act.
“We’re moving as quickly as we can, because there is an ecological, environmental need for speed. If you can save [damaged] willows, they'll grow back in an amazing way. But if you wait too long, then you lose them, and then you can really have a hard time restoring willow to that ecosystem,” Deacey said.
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