Rocky Mountain National Park has seen a notable shift in its wildlife over recent decades. While elk have long been a prominent species, moose have become an increasingly visible and integral part of the park’s fauna. These large ungulates, though once rare, now frequent various areas of the park. Their growing presence marks a significant development in the park’s ecological story.
Current Population Estimates
Estimating the precise number of moose in a vast and rugged area like Rocky Mountain National Park presents a challenge for wildlife biologists. The most recent comprehensive surveys, conducted in 2019 and 2020, estimated a population of approximately 149 moose in 2019 and 143 moose in 2020 within the surveyed portions of the park. These surveys covered roughly 65% of the park’s area, indicating that the overall park-wide population is likely an underestimate. Within the surveyed regions, the park’s moose population demonstrated an annual growth rate of about 5% during 2019 and 2020. This growth aligns with broader statewide trends in Colorado.
Moose Presence and Habitat
Moose are not historically abundant in the Rocky Mountain National Park area; historical records suggest they were infrequent, transient visitors prior to the late 1970s. Their current presence stems from reintroduction efforts initiated by the Colorado Division of Wildlife in 1978 and 1979. During these years, 24 moose from Utah and Wyoming were released into North Park, an area situated west of the national park. The first documented sighting of a moose within Rocky Mountain National Park occurred in 1980, in the Kawuneeche Valley.
Initially, moose sightings were largely confined to the Kawuneeche Valley on the west side until around 2011-2012. Today, these animals have expanded their range and are observed in all major watersheds, appearing with increasing frequency on both the east and west sides of the park. Moose are particularly drawn to habitats rich in water and dense vegetation, favoring willow thickets, riparian corridors, high-elevation wetlands, and marshy areas near lakes. Visitors frequently spot them in areas such as:
- The Kawuneeche Valley
- Along the Colorado River near Timber Creek Campground
- Lulu City on the west side
- Sprague Lake
- Cub Lake
- Horseshoe Park
Monitoring Moose Populations
Wildlife biologists in Rocky Mountain National Park employ a variety of methods to monitor moose populations and understand their behavior. Aerial surveys are a primary tool, utilizing thermal infrared and high-definition cameras mounted on aircraft to count moose from above. These surveys provide important data for estimating population size within specific areas. Ground observations also contribute to population assessments, offering direct visual counts and behavioral insights.
Telemetry and GPS collaring are important for tracking individual moose movements and habitat use. Biologists have fitted a number of moose with GPS collars, which transmit location data multiple times a day, providing detailed information on their range and how they utilize various habitats. Researchers also conduct vegetation surveys across 254 plots within the park to assess the impact of moose browsing on plant communities. Counting large, mobile animals in the park’s vast and rugged terrain presents difficulties, as moose often inhabit thick cover, steep drainages, and wetlands.
Ecological Significance of Moose
As large herbivores, moose play a significant role in shaping the ecosystems of Rocky Mountain National Park. Their foraging habits have a substantial impact on vegetation, particularly willow, which constitutes up to 91% of their summer diet. An adult moose can consume between 45 and 60 pounds of vegetation daily, leading to considerable browsing pressure on riparian and wetland plant communities. This intensive foraging can lead to degradation of these sensitive wetland habitats.
The absence of natural predators, such as wolves and grizzly bears, allows moose populations to grow with fewer natural controls. This lack of predation, combined with their specialized diet, contributes to an imbalance between the growing moose population and the available vegetation. For instance, one moose can consume as much willow as 15 elk. The Kawuneeche Valley has experienced a substantial loss of willow acreage and beaver pond surface water over recent decades, a trend exacerbated by moose browsing. The decline in willow populations also negatively affects other species, such as beavers, which rely on willow for food and dam construction, impacting the broader wetland ecosystem.