Mule Deer

A moderately large deer with large ears; antlers typically dichotomously branched and restricted almost entirely to males; metatarsal gland 8-12 cm long, narrow, and situated above midpoint of shank; upperparts in winter cinnamon buff suffused with blackish, more reddish in summer; brow patch whitish; ear grayish on outside, whitish on inside; tail usually with black tip and white basal portion; underparts white. Dental formula: I 0/3, C 0/1, Pm 3/3, M 3/3 X 2 = 32. External measurements average: (males) total length, 1,755 mm; tail, 152 mm; hind foot, 555 mm; metatarsal gland, 129 mm; (females) 1,453-175-475 mm. Weight, 57-102 kg.

Habitat & Diet

Mule deer occupy to some extent almost all types of habitat within their range but, in general, they seem to prefer the more arid, open situations in which sagebrush, juniper, pinyon pine, yellow pine, bitter brush, mountain mahogany, and such plants predominate. In western Texas , rocky hillsides covered with lechuguilla, sotol, juniper, and pinyon pine provide the essentials.

The food of the mule deer is quite varied. In Trans-Pecos Texas , the flowering stalks of lechuguilla, the basal parts of sotol, mesquite, juniper, and a number of forbs contribute to their diet. Feeding time varies with the weather, the phase of the moon, the time of the year, and type of country. During cold, snowy, winter months when food is difficult to obtain and a considerable amount is required to maintain body heat and energy, deer feed at all times of day and night. During the rutting season, feeding is often erratic, especially with bucks. During the hunting season, when many hunters are on the range, bucks do the major part of their feeding at night. Deer are more prone to feed on dark nights and are relatively quiet and bedded down when the moonlight is intense. In spring and summer, mule deer tend to feed to a greater extent upon green leaves, green herbs, weeds, and grasses than they do upon browse species; the reverse is true in fall and winter.

Reproduction

The rut begins in the fall, usually in November or December, but varies with locality and climatic conditions and continues until the latter part of January or even into February. During this period, the bucks have terrific battles in which the antlers are used almost exclusively. Bucks that are evenly matched in size and strength may fight until almost exhausted before one or the other is the victor. The animals are polygamous. The stronger, more virile bucks attract females to them and attempt to defend them against the attentions of the younger bucks. Small, persistent bucks can lead a large buck a miserable life, leaving him little time to take care of family duties or even to eat, because of his continued attempts to drive them away. In this period the necks of bucks become swollen, a development that is closely associated with reproduction.

The gestation period is approximately 210 days, and the fawning period extends over several weeks in June, July, and August. The female sequesters herself and drops her fawn in a protected locality where it remains for a period of a week or 10 days before it is strong enough to follow her. At birth fawns are spotted and weigh approximately 2.5 kg. They are nursed at regular intervals by the female, 10 minutes of nursing usually sufficing for a full meal. The young ones are weaned at about the age of 60 or 75 days, at which time they begin to lose their spots. The weaning time is a critical one because if green forage is not available, the fawns seldom make their transfer from milk to a diet of vegetation. If the fawn is not weaned, both mother and fawn are likely to experience difficulty in surviving a severe winter. Sexual maturity is attained at the age of about 18 months in does but ordinarily, young bucks are not allowed to participate actively in the rut until they are 3 or 4 years old.