The large ears of desert foxes help the animal to stay cool in the desert heat. Desert foxes also tend to be smaller than vulpines from other habitats.
Two of the most recognizable species of desert-dwelling fox are the fennec fox of northern Africa and the kit fox of the southwestern United States and Mexico. The large ears of these foxes provide extra body surface area that is laden with blood vessels. Desert foxes retreat to cool, shady areas and hold their ears erect. The blood vessels dilate and heat escapes through the ears, cooling the animal's body. Large ears also trap and amplify sounds. This is especially helpful for locating prey, such as small rodents, that move underground to avoid the desert heat.
The small size and long, dense fur of desert-dwelling foxes are other adaptations for their harsh environment. Smaller organisms require less water and food than their larger counterparts. The thick fur of fennecs and kit foxes provides insulation for cool desert nights while keeping excess heat away from the body during the day. Even the bottoms of the foxes' paws are furry, creating a snowshoe-like foot that prevents the animals from sinking too far into loose sand.