California mule deer, Odocoileus hemionus californicus, is a subspecies of mule deer whose range covers much of the state of California, including the San Bernardino Mountains and the San Gabriel Mountains in San Bernardino County.
The California mule deer’s antlers fork in an upward growth, distinguishing it from the closely related black-tailed deer and white-tailed deer, the antlers of which grow in a forward direction. It is named for its ears, which are large like those of the mule. The mule deer has a height of 31 inches to 42 inches at the shoulders and a nose to tail length ranging from 3.9 to 6.9 feet. Adult bucks normally weigh 120 to 330 pounds, averaging around 200 pounds. Does are smaller and typically weigh from 95 to 200 pounds, with an average of around 150 pounds.
Although capable of running, mule deer are often seen stotting, which is also called pronking, with all 4 feet coming down together.
The Odocoileus hemionus californicus subspecies is widespread throughout northern and central California in the California coastal prairie as well as inner coastal ranges and interior mountains, as well as the Sierra Nevada. This deer will much less frequently be found on the floor of the interior valleys, and then it will mostly frequent riparian zones.
Generally, the California mule deer has a preference for hill terrain, especially an oak woodland habitat. It is a browser and will typically take over ninety percent of its diet from shrubs and leaves and the balance from grasses.
California mule deer usually browse close to lakes or streams providing their water source. From that reference point of water consumption they may roam one to two miles, and typically make their beds in grassy areas beneath trees within such a one-mile distance radius from both water and forage.
Repeated beds will often be scratched to a nearly level surface, about six-and-a-half feet in diameter. Less regularly used bedding areas are manifested as flattened grass. On hot summer days California mule deer often seek shade and rest in the mid-day.
In summer, California mule deer mainly browse on leaves of small trees, shrubs and herbaceous plants, but also consume many types of berries, including blackberries, huckleberries, salal and thimbleberries. In winter, they may expand their forage to conifers, particularly twigs of Douglas fir, aspen, willow, dogwood, juniper, and sage. Year-round, they will feed on acorns; grasses are a secondary food source. Where humans have encroached on historic deer habitat by suburban development or orchards, California mule deer will diversify their diet with garden plant material, with tree fruit, and, occasionally, even with pet food.
Fawns and does tend to forage together in familial groupings while bucks tend to travel singly or with other bucks. California mule deer browse most actively near dawn and dusk, but will also forage at night in open agricultural areas or when experiencing hunting pressure.
Rutting season occurs in autumn when the does come into estrus for a period lasting only several days. Males manifest aggressive behavior in competing for mates. Does will begin estrus again if they do not mate. The gestation period is approximately 200 days, with fawns arriving in the spring. Mule deer females usually give birth to two fawns, although if it is their first time having a fawn, they often only have one. The young will remain with mothers throughout the summer and become weaned in the autumn. The buck’s antlers fall off in the winter-time but begin to regrow almost at once or by early spring in anticipation of the next autumn’s rut.
Since prehistoric times the Native American indigenous peoples of California are known to have hunted California mule deer. It appears that for 14,000 years human populations have served as a control to the numbers of California mule deer. In the modern era, since European colonists and Euro-Americans settled in California, hunting pressure intensified as the human population expanded and hunting became an activity associated with more than just food supply. In addition human population growth through urban development in California has consumed large amounts of natural habitat of the California mule deer starting in the late 19th Century and continuing through the present.
The mule deer’s several predators other than humans include mountain lions. This leading natural predator often select weak, sickly, or young deer to kill, but will also take down the largest and healthiest mule deer on occasion. Bobcats, coyotes, black bears are capable of preying on adult deer, but usually either only attack fawns or infirm specimens or eat the deer after it has died naturally.