September is an exceptionally good time to watch for Rocky Mountain mule deer (Odocoileus hemionus) in the desert. These large ungulates are on the move this time of year as they migrate towards winter ranges and enter into the breeding season.
Mule deer, also known as “mulies,” have interesting migration patterns. For those animals that spent the summer at higher elevations feeding on woody shrubs, wildflowers, and some grasses, these animals begin their descent to the lower sagebrush flats and pinyon-juniper woodlands to spend the winter.
Deer are in the genus Odocoileus which is derived from the Greek words odontos meaning “tooth” and koilos meaning “hollow.” Combined with eus, meaning “pertaining to,” the genus name refers to deep pits on the top of the grinding teeth. The species name hemionus means “mule” which refers to the animal’s mule-like ears which are about three-quarters the length of the head, from the base of the jaw to tip of the ear.
When you encounter a herd of deer, watch their ears. You’ll notice them changing angles or moving about as the creature tunes in to its surroundings. The slightest sound, such as a twig snapping, could mean a predator is nearby. Coyotes, mountain lions, humans, and wolves are the primary predators of mule deer; however, in southern Utah wolves are missing from this equation.
When alarmed, deer may bound away in a movement called “stotting,” which means all four feet are off the ground at the same time. Able to jump over a 4-strand barbed wire fence, mulies can also cover about 15 feet in a single bound. Add to these feats that a mule deer can do a 180 change-of-direction in midair.
In addition to having excellent hearing and flexible movement, mule deer also have decent eyesight. Their eyes are located on the sides of their head and afford a 310-degree field of view. Their night vision is especially good, able to see predators over 1,500 feet away. Though deer may be active during the day, they utilize the cover of darkness to move and forage leaving only their heart-shaped prints to indicate their passage.
The fall is also the rut or breeding season for these mulies. Bucks have regrown their antlers and shed the soft, velvety skin-like covering as their antler’s developed. At the rate of ¼” per day, these antlers stopped growing in August or early September. A mature buck may have forked antlers with 8 to 10 points with a spread that around 4 feet wide. These formidable antlers are used for jousting with rival males, posturing, and to attract females; if you’re really lucky you’ll hear the clickety-clack of antlers engaged in a fencing duel.
Though mule deer have these amazing qualities to survive in nature, they can’t compete against highway traffic. If you drive between Monticello and Blanding, notice the high fencing along Highway 191. The fencing channels animals, especially mule deer and elk, to underground passageways which provide a safer option for crossing the busy highway. Highway signage warns motorists about wildlife on the highway, helping to reduce impacts on these magnificent desert creatures.