mule deer


From Yellowstone Wildlife: A Watchers Guide 
by Todd Wilkinson.

Black-Tailed Browser

When you drive through Yellowstone, practically everywhere you go is mule deer country.

Nomads of the West, mule deer (Odocoileus hemionus) are ideally suited to the rugged slopes of the Rocky Mountains. Although there is no precise count of the mule deer population, "mulies" may number about 3,000 in Yellowstone, ranging over most areas of the national park in summer but migrating to lower elevations outside the park in winter.

Because mule deer are members of the cervid (deer) family, the males (bucks) flaunt symmetrical antlers that are shed late in the winter. The size of antlers is determined by genetic make-up and by the availability of nutrient-rich forage. Females (does) do not grow antlers.

Roadside indications of mule deer include tracks that resemble cloven half moons and range in length from 2 1/2 to 3 1/4 inches, depending upon the deer is size and sex. Other clues include beds of matted grass where mule deer rest during the heat of the day. The pellets of mule deer are similar to those of elk, taking the form of matted piles or dark brown balls.

Given their relative abundance in the greater Yellowstone area today, it's difficult to fathom that mule deer were once reduced to dangerously low numbers in the region by overhunting. At the turn of the century, the park served as one of the few sanctuaries for the species, and it continues to nurture trophy-sized bucks whose racks are coveted by sport hunters. Harvesting of any animal by hunters is prohibited inside the national park, though some mule deer are shot after leaving Yellowstone in the fall.

Nature has given this plant-eating animal the ability to identify its enemies and flee on a moment's notice. Three features make the mule deer easily recognizable: its oversized, creamy-white ears; its ropy, black-tipped tail; and its unique way of jumping and landing on all four feet at once, a gait called "stotting."

While mule deer bucks are polygamous, they do not amass harems of females like their elk counterparts. Males lead a solitary life except during the rut, while females congregate in groups on the same winter range year after year. This gathering is called "yarding."

The mule deer's physical size and preferred habitat further distinguish it from its smaller relative, the whitetail. The mule deer's coat takes on different shades as the seasons progress. Summer brings a reddish tint, while winter produces a covering flecked with gray that serves as camouflage during the snowy season.

The mule deer's muscular frame reflects the fact that its summer range may include grasslands located on steep summits as high as 10,000 feet. The primary enemies of mule deer in Yellowstone are mountain lions, coyotes, and grizzly bears, which prey on deer calves in spring. If wolves are restored to Yellowstone, they too will undoubtedly make mule deer a staple.

Despite its reputation as a browser, the mule deer's diet is highly complex. Mulies feed in mature Douglas-fir forests, but they are also creatures of the sagebrush flats. Studies have documented mule deer in the Rockies that eat over 673 different species of plants. While less discriminating in their cravings than pronghorn and bighorn sheep, mule deer often embark on foraging expeditions taking them 30 miles or more in a night. They feed on grasses during spring and summer, and on branches of trees and sagebrush-juniper in the winter. Such palatable greens now flourish in many burned sections of Yellowstone following the historic 1988 forest fires.

Where to Find Mule Deer

The Lake, Tower, and Mammoth areas contain mule deer during most of the year. The crepuscular mulies are also seen frequently from the roadside on the south shores of Yellowstone Lake near Grant Village, and on the lake's northern shores from Bridge Bay to Lake Butte. Check also near Old Faithful, and between the northeast entrance of the park and Lamar Valley. Continue to the next page, A Thousand Winters Ago - History of the Pronghorn.

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