• Photo of early morning clouds hanging low in the valley with mountains of the Continental Divide stretched out above. NPS Photo/Schonlau

    Rocky Mountain

    National Park Colorado

Mule Deer


Mule Deer Buck

NPS Photo


The mule deer was so named for an obvious reason-those oversized ears. Like a mule's.

Naming this elegant western mammal was easy enough. Protecting the herds proved to be a more difficult proposition entirely.

Upon their arrival in the early 1860s, the first Estes park area settlers found moderately abundant numbers of mule deer. The growing population of newcomers, predators, and the often harsh elements took huge numbers of the animals. In 1895, according to one report, very few mule deer were seen in the Estes Park region, and even by 1906, "I heard of none in the foothills of Boulder and Larimer counties."

Mule deer became so scarce throughout Colorado that in 1913, a statewide hunting ban was put in effect. Dedication of Rocky Mountain National Park in 1915 and the subsequent removal of most predators resulted in a dramatic increase in the mule deer population. In 1930 an estimated 2,500 roamed the park.

Today several hundred mulies reside in Rocky Mountain National Park. The park's population is believed to be stable or increasing.

Mule deer play an important role in the wildlife food chain. They are the primary prey of mountain lions. Mule deer also can be taken by coyotes and bobcats. Unfortunately several also fall victim each year to a mechanized predator, the automobile.

Mule deer doe

Mule Deer Doe

Habitat and Distribution

Mule deer commonly are seen browsing in open, shrubby areas between dusk and dawn. Easily distinguishable from its cousin, the elk, by its smaller size, large ears, black-tipped white tail, and white rump patch, the mule deer browses shrubs, trees, and occasional grasses and forbs, retreating to tree cover to bed down for the day. Studies on Specimen Mountain in the park indicated that shrubs comprised 73 percent of the animal's diet, broad-leafed herbs an additional 26 percent.

Winter snows drive mule deer from their higher summer ranges to the park's lower elevations. Upon summer's return, bucks often are seen at or above treeline while does appear to favor forest edges at slightly lower elevations.

a photo of mule deer fawns nursing

Mating and Breeding

Mule deer bucks shed their antlers in winter, growing new ones annually. In November, with the males’ antlers now fully mature and worn free of velvet, the deer rut begins.

Unlike elk, mule deer do not collect harems or bugle during the fall mating season. A male will locate a willing doe and discourage competitors until mating occurs. Most often, a dominant male can run off other prospective suitors through threatening body postures and movements intended to establish dominance. On other occasions, mature bucks engage in violent jousting contests, using their impressive racks as weaponry.

When the rut is over in December, the does and bucks separate, the females and young forming herds and the males collecting in loose bands or going it alone. Exhausted by the autumn rut, many bucks fail to survive the rigors of winter.

About 200 days after mating takes place, a single or twin birth occurs, pairs often being born to does after their first pregnancy. The spotted nursing fawns spend the day hidden in the underbrush while the mother is away feeding. The youngsters are without obvious odor that would give them away to predators. Fawns will be able to accompany their mother within a few weeks.


Mule Deer Viewing

Those large ears are not just for show. Mule deer have excellent hearing and eyesight that’s almost equally efficient. Despite the fact that they probably are well aware of your presence, mule deer often show little fear of humans.

Those beautiful mammals provide many Rocky Mountain National park wildlife watchers with memorable outdoor encounters. Please treat them with respect and do not approach them. Between predators, the rigors of mating season, and the harsh Rocky Mountain mountain winters, life for the park’s mule deer is challenging enough.

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