With a lifespan that can reach up to 22 years, these deer are built for endurance and adaptability, showcasing an impressive ability to navigate the diverse terrains of California, from coastal prairies to the Sierra Nevada mountains.

In the warmer months, their coat tends to be a lighter, reddish-brown shade, which helps them blend into the dry, sunlit landscapes.

Conversely, during the colder months, the coat becomes a darker, more muted brown, offering better camouflage in the denser, shadowed terrains and against the backdrop of leafless trees or snow.

These color changes are a process called molting, driven by a complex interplay of hormonal changes, photoperiod (length of daylight), and temperature.

As the days lengthen in spring and shorten in fall, the pineal gland in the brain alters its melatonin production, signaling the body to initiate the molting process.

This coat is characterized by longer, denser, and darker hairs that have a hollow structure, trapping air and providing better thermal insulation against the cold.

[7] Mule deer are often opportunistic and will consume a large variety of vegetation mainly consisting of whatever is available and easily digestible including stalks, flowers, fruits, seeds of grasses, forbs, buds, seeds (particularly acorns), stems, leaves, the bark of trees, shrubs, fungi, lichens, algae, mosses, and ferns.

In summer, California mule deer mainly browse on leaves of small trees, shrubs, and herbaceous plants, but also consume many types of berries (including blackberry, huckleberry, salal, and thimbleberry).

In winter, they may expand their forage to conifers (particularly twigs of Douglas fir), aspen, willow, dogwood, juniper, and sage.

California mule deer browse most actively near dawn and dusk, but also forage at night in open agricultural areas or when experiencing hunting pressure.

Females will spend their summers isolated in fawning areas after their young have sufficiently grown, where they will remain until the breeding season begins again in the fall.

The familial structure during this period is typically a mother-and-fawn unit, while mature bucks generally keep to themselves or form small bachelor groups.

[9] Bobcats, mountain lions, coyotes, and American black bears are all common predators of California Mule Deer.

Thus, since about 12,000 BCE, Gage suggests that human populations have served as a control to the numbers of California mule deer.