Mule deer feed mostly at night and return to heavy or rough cover during the day. They browse on a wide variety of woody plants but also graze forbs and grasses. In Kansas, they often consume corn, milo, soy beans, and alfalfa in addition to native plants.
Predation in Kansas is heaviest on fawns, primarily by coyotes. The most important predators on adults are pumas, coyotes, and dogs. Other important sources of mortality are vehicular traffic and hunting.
Measurements of adult males, followed by those of adult females, are as follows: total length 1370-1800 mm, 1160-1800 mm; length of tail 150-230 mm, 110-200 mm; length of hind foot 410-590 mm, 325-510 mm; length of ear 120-250 mm, 120-240 mm; weight 50-215 kg, 33-72 kg. Females reach maximum size in about 2 years, whereas males continue growing until they are 9 or 10 years old. Mule deer are larger than white-tailed deer but less than half the size of elk. Mule deer may survive up to 20 years in the wild, but such longevity is rare and population turnover is high.