The desert is home to rare and magnificent creatures like bighorn sheep, desert tortoise, fringe-toed lizard, and several species of birds. Desert animals face many challenges to survival and have developed a multitude of fascinating adaptations to endure the harsh conditions. The most crucial behavioral techniques are avoiding heat, dissipating heat, retaining water, and acquiring water, all of which require an intact functioning ecosystem.
Behavioral techniques for avoiding heat are numerous among desert animals. Certain species of birds, like the phainopepla, will breed in the cool seasons and then fly to higher elevations or coastal areas when the desert temperatures become extreme. Other birds are most active near dawn and then retire to a cooler, shady spot until dusk when their activity resumes; yet others will remain active all day, while limiting their activity to a shady perch. Many mammals and reptiles are crepuscular, meaning they are only active at dusk and dawn. These animals are usually sleeping in a cool den, cave, or burrow by day. Other animals like owls and bats, are completely nocturnal, restricting all of their activities to the cooler night temperatures. Some desert reptiles, such as desert iguana, are active during the heat of the day, but move very quickly over hot surfaces and then rest in shaded areas to cool themselves. Still other desert animals sleep away the hottest part of the summer through a state of estivation (they may also hibernate in winter to avoid the cold season).
Dissipating heat is especially beneficial for desert animals, but not all of them can do it. For example, small creatures like beetles and lizards have long limbs to dissipate body heat. Jackrabbits have big ears lined with shallow blood vessels, which allows air to cool their blood as it circulates. Owls gape open-mouthed to cool themselves by evaporating water from their mouth cavity. Other desert animals have pale feathers, fur, scales, or skin to reflect sunlight (and camouflage them from predators).
Acquiring and Retaining Water
The adaptations of desert animals for acquiring and retaining water are even more elaborate. Some rodents and insects consume cacti and other plants, while others like snakes, ingest water when they consume their prey. Some desert animals retain moisture by simply burrowing into moist soil during the day. Others like kangaroo rats, obtain water by storing seeds in their burrows, where they absorb moisture from the air; the animal later obtains that moisture by eating the seeds. Some reptiles and birds excrete solid metabolic waste in the form of uric acid and expel very little water in the process. Still other animals such as the desert tortoise and antelope ground squirrel have specialized organs that recapture precious water from their urine, and the kangaroo rat will even seal themselves in their underground den to recycle moisture from their breath! Large desert mammals, like bighorn sheep, are somewhat reliant on springs, rivers, and other sources of water. Reliance on outside water sources limits the territory of these animals, as distances between water sources are often too great.