Mule deer (Odocoilus hemionus) and a subspecies called black-tailed deer survive in the arid semi-desert of the U.S. southwest. The large ears, the reason for the name, can move independently to provide warning of predators, which might be coyotes or cougars. The gray-brown coloring of mule deer, which helps the deer blend in with their surroundings, is one adaptation for survival in the desert. Large feet are another adaptation. Mule deer can smell water underground and then claw the ground to get to water as much as 2 feet underground. These deer find a cool place to sleep during the hottest part of the day and find food early and late when the temperatures are cooler.
The dama mesopotamica, also called Persian fallow deer, once lived in desert areas from Iran to Turkey. Few Persian fallow deer survive today. Some live in wildlife refuges in Iran. In 1996 Israel began a reintroduction program, and in 2010 the International Union for Conservation of Nature reported about 250 wild Persian fallow deer in northern Israel.
The white-tailed deer (Odocoileus virginianus) is named for the white underside of its tail which it holds up like a flag when it is startled or threatened. The species is very adaptable and can be found living in semi-desert areas if there is water within 10 miles. White-tailed deer usually live in forested areas, but some have adapted to desert conditions. Desert areas provide food for the deer in the form of prickly pear cactus and various tough shrubs. Like the closely related mule deer, white-tailed deer rest during the hottest part of the day to keep their body temperatures in a range they can survive.
.
Survival in the desert requires adaptations to digest the food deer can find. White-tailed deer in the forest eat leaves, nuts and fruit. In the desert, they eat cactus and shrubs. Deer also migrate to areas where they are more likely to find food, going to higher elevations in the summer or possibly following rainfall patterns. An excellent sense of smell helps deer find food and water even when both are scarce.