Peninsular Mule Deer, Odocoileus hemionus peninsulae

Peninsular Mule Deer, Odocoileus hemionus peninsulae. Photograph taken within a residential community in the Greater Los Cabos area, Baja California Sur, November 2019. Photograph courtesy of Martha Correa, San José del Cabo, Baja California Sur.

The Peninsular Mule Deer, Odocoileus hemionus peninsulae, is a member of the Cervidae family of Deer. The Cervidae family consists of approximately forty-three members placed in three subfamilies and nineteen genera. However, there is ongoing debate over the classification of the Cervidae family. There are two species in the Odocoileus genus. The Peninsular Mule Deer is one of ten subspecies of Mule Deer, Odocoileus hemionus. Mule Deer are one of the most widely distributed and abundant of all large mammal species in western North America. The Peninsular Mule Deer is known in Mexico as Venado Bura Península.

Peninsular Mule Deer can easily be identified by their large ears that move independently from one another. They are grayish brown in color with a small white rump patch. Their tail is short and white with a black tip. They have bifurcated antlers that “fork” as they grow and shed during the winter months. Antler size is influenced by age, level of nutrition, and genetics. They range from 80 cm (2 feet 6 inches) to 1 m (3 feet 3 inches) in height at the shoulders and have a snout-to-vent length of 1 m (3 feet 3 inches) to 2 m (6 feet 11 inches). Their tail reaches 12 cm (5 inches) to 23 cm (9 inches) in length. Males can weigh between 55 kg (121 lbs) and 150 kg (331 lbs), while females are smaller and weigh between 43 kg (95 lbs) and 90 kg (198 lbs). 

Peninsular Mule Deer are active during both the daytime and nighttime hours, and most active at dusk and at dawn. They maintain family groups that consist of at least two generations of related females and their male and female offspring. The adult bucks separate from these groups and either remain solitary or form all male groups. However, bucks rejoin their family groups in late summer and fall in preparation for breeding. Reproduction is polygynous, with the females mating with more than one male until they become pregnant. Gestation lasts between 190 and 200 days before one or two fawns are born in the late spring. Fawns weigh between 2 kg (4 lbs 8 oz) and 5 kg (11 lbs 0 oz) and larger fawns have a greater chance of survival. Fawns remain hidden during their initial six to eight weeks and can be separated from their mothers for long periods of time. They begin to consume green vegetation within two weeks and are weaned after 60 days. They grow rapidly and will stay with their mother for a year until just before she gives birth. Fawn survival during the first year is less than 50%, with major losses due to predation and malnutrition. They have life spans of up to twenty years. 

Peninsular Mule Deer consume a wide variety of plants that have a seasonal, geographic and elevational variation depending upon availability. Their diet consists of high-quality, easily digested food such as stalks, flowers, fruits, and the seeds of grasses and forbs from several hundred different plant species. They also enjoy agricultural products and landscape plantings. Their livelihood and longevity are strongly dependent on adequate amounts of rainfall, which controls food availability. Some migrate for distances up to 160 km (100 miles) over a four to seven week period to obtain shelter and food, while others stay at the lower elevations year-round. Regardless, their home ranges are the same year to year. They are found in desert shrublands at lower elevations during the winter months, mountain shrublands at mid-elevations, and some forests at higher elevations during the summer. They are primarily preyed upon by Coyotes and hunted by Humans. They have the ability to run but normally “pronk” with all four feet landing simultaneously.

The Peninsular Mule Deer has a limited range, being found only throughout the Baja California Sur. They require cover, for security and protection from the heat, and access to water. Dry washes are important as they provide food, resting areas, escape, and travel cover throughout the year. 

From a conservation perspective, the Peninsular Mule Deer has not been formally evaluated by the IUCN. More information is needed to determine their population trends and susceptibility to human disturbance. Mule Deer can be are considered to be of Least Concern due to their adaptability to a wide range of habitats, large populations, occurrence in a number of protected areas, and apparently stable population.