Beaver, moose, beetles, fire and climate: How Rocky’s forests are being remade

Rangers from Rocky Mountain National Park told an Estes Park audience of nearly 100 listeners last week that Rocky’s forests and wildlife are being shaped by a mix of long-running ecological pressures, past land management decisions, and a warming climate.

Speaking at a League of Women Voters of Estes Park “Learn with the League” program on Wednesday, RMNP ecologists outlined how mountain pine beetles, wildfire risk, prescribed burns, and growing moose population are changing conditions across the Park.

The presentations offered both a history lesson and a warning: the massive mountain pine beetle outbreak that peaked in 2009 was not a random event, and some of the same conditions that helped fuel it are again raising concern. The presentations also offered a look at how the Park is managing the growing moose population, which has decimated willows and, in turn, affected beavers, and how the Park is addressing the problem.

According to information provided by RMNP large mammal ecologist Will Deacy, in 1940 the Park had 315 beaver colonies in Moraine Park. In 2024, the Park counted only six. The impact has been even more dramatic in the area of the Colorado River Drainage, as the number of beaver colonies fell from 630 in 1940 to 6 in 2024.

The density of moose in RMNP has increased 49% over the past 6 years, and the number of moose is now at 240. For comparison, that is equivalent to 3,600 elk in terms of ecological impact.

Deacy reported that there have been eight unique wolves detected in RMNP since their reintroduction in 2023 and while wolves are a natural predator of elk, wolves are not a predator of moose that can help keep the population in balance.

Ecologists have documented that the systematic eradication of wolves from Colorado by the mid-1940s contributed to a host of ecological problems, but their reintroduction does not reverse the damage.

A forest shaped by its past

Kevin Gaalaas, a Rocky Mountain forest ecologist, said the scale of the earlier outbreak was driven by a combination of dense, even-aged lodgepole pine stands, drought stress, warm winters, and a landscape made unusually vulnerable by past disturbances and human management.

Large fires in the 1800s helped create broad stretches of similar-age forest, and later logging operations removed a key middle-aged class of trees, then decades of fire suppression further reduced the patchwork, or mosaic, of species and ages that would have made the forest more resilient, explained Gaalaas.

“The stars just aligned perfectly,” said Gaalaas, describing the conditions that led to the largest mountain pine beetle outbreak in Colorado history.

Warming temperatures are also allowing beetles to complete their life cycle more quickly at higher elevations, expanding the areas where they can thrive.

Because about one-third of Rocky is above tree line, the remaining forested landscape carries the bulk of the impact. Half of the Park’s forested land is dominated by pine, and about 70% of its forests contain significant pine presence, making the effects of beetle activity widespread.

According to Gaalaas, during the last major outbreak, the Park focused much of its response on hazard tree removal in heavily visited areas such as campgrounds, roadsides, and developed front-country sites. In some places, staff removed not only dead trees but living trees newly exposed to wind after surrounding dead trees were cut.

The Park also protected selected high-value trees with carbaryl insecticide treatments and with verbenone, a synthetic version of a beetle pheromone that signals overcrowding and can repel additional beetles.

Concerning signs of new beetle activity have recently been detected in several areas, including Moraine Park Campground, Upper Beaver Meadows, and the Alluvial Fan area. In Moraine Park Campground alone, the Park lost 29 trees to mass attack in 2024 and 2025.

Gaalaas said RMNP is closely watching for fresh pitch tubes on green trees, a sign beetles are still active, and larvae may still be inside. If crews can find and remove or strip bark from an infested tree before the brood emerges, they may prevent hundreds of beetles from moving on to nearby trees.

Although some factors may limit the odds of another Park-wide epidemic soon — including the loss of many susceptible trees in the last outbreak — the outlook is mixed. Climate change, recent drought, warm winters, regional beetle activity, and recent mass attacks inside the Park all point to reasons for concern.

Fire as both threat and tool

Nate Hallum, a fuels specialist, spoke about RMNP’s fire mitigation program, describing prescribed burning and fuels reduction as critical tools for both community protection and forest health.

According to Hallum, a front-country prescribed burn plan began in late 2024 that will continue, conditions permitting, through fiscal year 2029 across nearly 2,000 acres.

Those burns are aimed in part at creating a buffer west of Estes Park that could help firefighters slow or engage a wildfire moving toward the Town from the Park. The burns are also intended to restore more natural conditions and reduce unnaturally heavy fuel loads that have built up over roughly 150 years.

Hallum said prescribed burns are planned months or years in advance, with work including fireline preparation, obtaining smoke permits, weather analysis, and coordination with local, county, and federal partners.

Burns are not conducted unless crews are operating within strict weather and fuel-moisture parameters, and RMNP staff consult the National Weather Service before ignition.

To monitor smoke, he said, the Park uses publicly available PurpleAir sensors across the community, which collect hyper-local, real-time air-quality data. If smoke impacts become too heavy, crews shut operations down, though nighttime smoke settling remains difficult to avoid.

Hallum described pile burning and thinning work already underway or planned in areas including Lily Lake, Thunder Mountain, Eagle Cliff, Deer Mountain, and Wild Basin. And in Wild Basin, the Park is beginning to examine strategies to improve road access and create safer evacuation and firefighting corridors.

According to Hallum, the goal is not to remake the forest overnight, but to begin restoring a more varied landscape that can better withstand fire, insects, and drought.

“Be patient with us,” Hallum told the audience. “We’re trying to do our best.”

Questions and answers

Audience questions ranged beyond beetles and burns to moose, elk, beavers, bighorn sheep, staffing, and timed entry.

One audience member asked about management of the moose population, which is growing rapidly in Rocky, at about 8.5% a year, even though calf-to-cow ratios appear low.

Asked directly about whether the Park is using culling as a management strategy, the official said the park is not yet prepared to discuss specific actions, but it is monitoring the population as moose continue to heavily browse willow, one of their main food sources.

Exclosures used to protect willow and aspen from moose browsing have been successful, but most existing fences are near roads and may not be practical in more remote areas.

On disease, the Park staff have not seen winter tick, a major problem for moose populations in some northern regions, and continue to monitor collared animals and carcasses for signs of illness.

Gary Ingram, superintendent of Rocky Mountain National Park, responded to a question about Park staffing. Ingram said RMNP typically has about 200 full-time staff and roughly doubles that in summer with seasonal hires.

According to Ingram, the Park is in relatively strong shape heading into the season and has recently been granted local hiring authority, which could ease staffing pressures tied to housing shortages.