Bears Colorado's eight to twelve thousand black bears usually begin their nap between mid-October and mid-November, though some insomniacs wait until December. Physiological changes within the bear are timed to correspond with shortages of food and seem to be unrelated to variations in climate from year to year. Bear specialist Tom Beck studied black bears in west-central Colorado from 1979 to 1986 and discovered that females enter dens about two weeks earlier than males and leave about two weeks later. He also found that denning bears prefer rock caverns with very small entrances, though they also dig dens under shrubs, often choosing serviceberry bushes. Sometimes they simply go into dormancy on the surface of the ground. The purpose of dens appears to be isolation and defense against predation rather than thermal insulation.
Although black bears are the common Colorado bear species, a few grizzlies may still inhabit remote areas in the San Juan mountains. A grizzly sow was killed when she attacked a bow hunter there in 1979. Researchers examined the layers in her teeth, which are used like tree rings to establish age. Close-together rings indicate physiological stress, which occurs when a sow nurses cubs and shortchanges her own nutrition. This sow's teeth showed she had borne cubs; the cubs were never found.
Grizzlies usually hibernate from November to April. But in 1996 researchers in Glacier National Park discovered fresh tracks in January and February near fresh wolf and mountain lion kills. The increased availability of food may be changing grizzly hibernation patterns.
Where to go: Black bears snooze throughout the state, all the way from the foothills to above tree line, although they seem to prefer higher elevations for their hibernacula. The den may be a cave, a hollow log, a rock crevice, or the hollow under tree roots or in thick brush. However, we don't recommend crawling into a den and arousing the bear, especially with a rectal thermometer in the manner of researcher Tom Beck!
Dueling Deer
Mule deer bucks begin to shed the soft brown velvet from their antlers in September and often indulge in playful sparring. By November the sparring is no longer playful. With all the style of a Cyrano de Bergerac engaging the enemy, they wield their antlers fiercely in duels for the favors of a doe. Earlier in the year the bucks ignored the females and traveled together-a perfect example of male bonding. But now they travel separately searching for does in estrus. And when two males want the same doe, the battle begins.
Much of the battle is bluff. The stiff-legged combatants shake their heads and lay back their mulelike ears, showing off magnificent antlers and heavy, swollen necks and shoulders. Sometimes they charge. Usually the less dominant buck retreats. If not, the fencing begins, with antler points as sharp as stilettos. It's usually not a duel to the death, though they may wound each other. On rare occasions the antlers interlock, and both warriors die in a grisly embrace.
Unlike elk, deer do not collect harems. Instead, a buck will follow a female in estrus until she is ready to mate (at which point you might say, the buck stops here), and he will fight other interested males. This type of behavior is called"tending."
By late December the rut is over, and the pregnant does, whose fawns will be born in June and early July, separate from the males until another autumn. In February and March the bucks shed their antlers and begin to grow a new set for a new season.
Where To Go: Mule deer can be seen in almost all habitats throughout the state, especially in brushy and riparian areas and along edges between forests and meadows. According to Fitzgerald, Meaney, and Armstrong in Mammals of Colorado, the highest densities are in the Piceance Basin in northwestern Colorado, the Gunnison River drainage, and the foothills of the Front Range. However, it would be easier to tell where they are not found than to enumerate the areas they inhabit.
In fact, there are more deer now than a century ago. In Rocky Mountain Mammals, David Armstrong quotes Merritt Cary, an early biologist, who wrote that a few mule deer had been reported in the Estes Park region in 1895 and none in the foothills of Boulder and Larimer Counties in 1906. Today Colorado has one of the largest mule deer populations of any state. The Division of Wildlife estimates the current population at about 600,000.
Smaller than their cousins and lacking the "mule ears," white-tailed deer can be recognized by the broad tail, which is white underneath and is raised like an alarm flag when they run. Their antlers have several points coming out of the main stem as opposed to the Y-shaped forks of mule deer.
Like mule deer, the white-tails also battle and breed in November, though their rut usually begins in October. Unlike mule deer, male and female white-tails may remain together in herds even after the rut.
Deer and elk frequently cope with deep snow by a process called "yarding," in which they gather together, usually in a forest opening, and trample down the snow cover. This strategy gives them more freedom of movement, relieving them from floundering in the drifts. However, food becomes scarce in these areas, and the animals are especially vulnerable if they are spooked or chased away from the firm-floored yard by domestic dogs or other predators. They can't afford to squander energy in winter.
Because of food scarcity, both deer and elk expand their diets in winter to include more woody shrubs. In hard winters they also consume more conifer needles, which contain chemical compounds from which turpentine is derived. In Winter, Jim Halfpenny and Roy Ozanne write that some American Indian tribes made a drink from pine needles to induce abortion and that a diet high in needles during fall and early winter may cause spontaneous abortion in deer-a way of limiting population during times of food scarcity.
Where To Go: White-tails prefer brushy riparian areas. In 1947 the Colorado Division of Wildlife reported no resident populations. However, human activities such as farming and timbering plus the increase in cottonwoods along rivers have favored the spread of white-tails from the East into the state. They are most common in the eastern plains and foothills, especially along the South Platte River. On the Western Slope, some herds are thriving along the White and Yampa Rivers.
© Article copyright Pruett Publishing.
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