Where Are Moose in Aspen Coming From?


Where Are Moose in Aspen Coming From?

Moose aren’t native to Colorado and the Roaring Fork Valley, but you’d never know it.

They’re the largest member of the deer family and found throughout the northern regions of North America, but historical records dating back to the 1850s indicate only the occasional, transient moose wandered into northern Colorado from Wyoming, according to Colorado Parks and Wildlife (CPW). They did not establish a breeding population.

State wildlife officials first began considering bringing moose (Alces alces) to Colorado in the 1950s, but it wasn’t until 1978 that 24 male and female moose from Wyoming and Utah were brought to the North Park area of Colorado to create a breeding population and hunting opportunities, according to CPW. Additional reintroduction efforts followed around the state, including the release of 91 moose in the Grand Mesa National Forest, to the west of the Roaring Fork and Crystal River valleys, in 2005-2007.

It was only a matter of time until the animals began to wander in Aspen’s direction.

At first, local moose sightings were sporadic – a bull moose startled a couple of anglers on the Fryingpan River in 2007. Another one was spotted in Missouri Heights at about the same time. In 2008, a young bull moose attracted a crowd when it strolled into the parking lot at the Orchard Plaza shopping complex in the midvalley, having wandered more than 50 miles from the Grand Mesa. CPW tranquilized the animal and returned it to the Mesa. These and other sightings were generally celebrated as exhilarating interactions with a species that many Coloradans had never seen before.

By 2010, sightings were increasingly frequent, thanks in part to a pair of female moose that took up residence in the vicinity of Maroon Lake. Trackable by their ear tags, the cows were identified as siblings that were transplanted from Utah to an area southeast of Gunnison after their mother was injured and had to be euthanized. The young cows made their way north to Aspen, some 40 miles distant. Nature being what it is, a bull found his way to the Maroon Creek drainage in 2012 and by the following spring, there were moose calves at Maroon Lake. The animals have made a place for themselves at the scenic, tourist hotspot ever since.


With an estimated 3,000 moose now inhabiting Colorado, including an unknown, but growing number in Pitkin County, interactions with moose are becoming commonplace and, occasionally, scary. Moose are the state’s largest wildlife species and the most dangerous. Adults weigh 800 to 1,200 pounds and bulls stand up to 6 feet tall at the shoulder. They may live up to 20 years in the wild.

Though their countenance and behavior sometimes make moose appear pleasantly docile, they are unpredictable animals that behave aggressively when they perceive a threat. Because dogs remind moose of wolves, one of their only natural predators, moose attacks on humans often involve dogs, according to CPW. Keeping dogs leashed while hiking is important for the protection of all involved in a moose encounter.

The best approach in dealing with a moose is to not approach. CPW suggests the “rule of thumb” measure – if you see a moose, stick your thumb out at arm’s length. If the thumb covers the moose, you are theoretically a safe distance away. If you surprise a moose, back away slowly. If the moose licks its snout, pins its ears back or raises the hackles on its neck and back, it may be ready to charge. You cannot outrun a moose (unless you can run 35 miles per hour).

Instead, put something large between you and the moose – a stout tree trunk, a boulder, a car, etc. If a moose attacks, it attempts to stomp its intended target, be it a dog or a human.


Pitkin County’s North Star Nature Preserve is perfect moose habitat, and the animals are seen regularly there. While a float down the Roaring Fork River through North Star has become a popular pastime during the summer months, the preserve is managed first and foremost for wildlife.

Signs warn river users about the potential for moose encounters at North Star and the risks such interactions pose. Open Space and Trails rangers may close access to the Preserve in the event of aggressive moose behavior.

Keep in mind, dogs are not allowed to float the river through the preserve and are not permitted anywhere on the land at North Star. Paddlers are required to stay on their watercraft for the North Star float and should be prepared to stop a safe distance from a moose – 100 yards, or the length of a football field, is advisable – and wait until the animal moves on. It could be a long wait.

Moose are an exciting addition to the watchable wildlife at North Star and elsewhere, but they demand a new level of caution in the pursuit of outdoor recreation. Be prepared to encounter them just about anywhere, whether it’s downtown Aspen, Smuggler Mountain, Hunter Creek or the Rio Grande Trail. Moose cover impressive distances as they pursue their favored habitat – marshy or riparian areas with willows for forage.


Within the Roaring Fork Valley, opportunities to harvest a moose have grown along with the moose population. Moose hunting takes place in September and October.

In 2019, the only local Game Management Unit (GMU) with an available moose license was GMU 43. which covers an area south of the Roaring Fork River from roughly Glenwood Springs to Castle Creek near Aspen. One bull license was available. In 2021, one cow license and one bull license were available in GMU 43, and one bull and one cow were harvested. CPW is proposing two bull licenses and one cow license in GMU 43 this year.

In addition, one cow and two bull licenses are now available for the combined units of 47, 471 and 444. GMU 47 covers most of the area north and east of Highway 82, including Woody Creek and Hunter Creek; GMU 471 encompasses the area south of 82 from Independence Pass to Castle Creek. Last fall, all three hunting tags resulted in harvests – one cow and two bull moose were taken.

Safety and Moose Behavior

Moose have very few natural enemies in the wild and, as a result, do not fear humans as much as most other big game species. Moose tolerate humans longer and at closer distances. They are extremely curious and often will approach humans or houses, and even will look into windows. For these reasons, it is extremely important to understand moose behavior when living in or visiting the areas they inhabit.

Female moose (cows) are very protective of their young (calves), so they can be dangerous if approached or caught off guard. Bulls can also be aggressive and territorial, especially during the breeding season (rut) in the fall. Moose have also taken over feed yards and haystacks and will defend them from any and all intruders, whether they’re livestock or human.

These formidable beasts need their space and must be given command and respect when observed in the wild.

•Signs of moose aggression include laid back ears, raised hairs on the neck, and licking of the snout

•Avoid animals that are behaving belligerently or abnormally.

•Keep pets away, as moose can get quite aggressive around them. Be especially cautious when walking dogs.

•If a moose displays aggressive behavior or begins to charge, run as fast as you can and try to put a large object between you such as a boulder, car or tree

While moose encounters with people are quite common, moose cause few problems. However, moose have “treed” people who have approached them too closely, have killed or injured pets or livestock, and have chased people away from territories they are defending. Caution and common sense go a long way in preventing potential problems with moose.

Watching Moose

•Look for moose sign—large tracks, droppings, browsed willows—along the edges of willow bottoms and aspen or pine forests. It will be evident if moose are present.

•Moose tracks are very large and often show dewclaws (a rudimentary claw or small hoof not reaching the ground) in snow or mud.

•Find a high spot that looks down into drainages for an excellent vantage point.

•Drive slowly along logging roads on national forest lands that parallel drainages.

•Moose sounds are limited to grunting, with bulls being the most vocal during the mating season.

•Moose do not herd into large groups as do many species of big game, even in winter. They prefer to travel in small family groups or to remain secluded.

•Never approach moose too closely. Watch and photograph from safe distances using telephoto lenses, binoculars and spotting scopes.

•Move slowly and not directly at them. Back off if they exhibit signs of aggression, such as the hair on their neck standing up, licking their snout, cocking their head, and rolling their eyes and ears back.

•Moose are excellent swimmers and very much at home in the water, which can be a good place to view them.

— Colorado Parks & Wildlife

This article was originally published on Pitkin County Open Space and Trails’ blog site. It has been updated with changes that have occurred since that time, including the latest moose harvest data from Colorado Parks and Wildlife. Find all of the Open Space and Trails blogs at http://www.pitkinoutside.org/ecofinder/learn/.

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