Deserts cover about one-fifth of the land surface on Earth. Despite the extremely difficult living conditions, such as dryness and intense heat, a wide variety of organisms survive well in desert environments. In fact, after tropical rainforests, deserts have the most variety in their flora and fauna. Desert animals have specific adaptations that separate them from animal species in other environments and that help them survive.
The easiest way for desert animals to survive is to simply avoid the harsh sunlight. Many are nocturnal, meaning they leave their shelters only at night to get food. Birds and bobcats are crepuscular, or animals that move around in the cool dawn or dusk hours. Desert animals may follow a seasonal pattern such as flight migration for birds. The javelina, a small, pig-like animal, comes out only in the daytime during the desert's winter months.
Some animals can use their surroundings for protection from the sun. Birds can perch in trees, if there are any, or reside in niches on the sides of cliffs. Other animals have to manipulate their environment for protection. Small mammals, such as kangaroo rats and white-tailed antelope squirrels, burrow under the ground. This temperature is not only much cooler, but it also remains stable from the fluctuating changes on the surface, where temperatures can range from more than 37.8 degrees Celsius to almost freezing within a 24-hour span.
Larger animals who are unable to make underground burrows have adapted to the heat in different ways. In general, desert animals have lighter and paler fur or skin, as seen with the elephant or desert jack rabbit. This adaptation allows them to blend with surroundings to trick predators and help dissipate sun exposure. The jack rabbit also has the advantage of having large appendages, their ears, to release heat trapped by their bodies. Large birds of prey, such as owls and nighthawks, have a panting method to keep cool. They open their beaks and vibrate the muscles of their throats to evaporate water.
There are several methods that different animal species have adapted to help them retain and gain water. Desert toads burrow deep into soil to keep their skin moist. Scavengers and predatory animals, like the turkey vulture, obtain their water source from the water content of their prey, yet they still drink water whenever they come across some. Insects find water from taking fluids directly from any desert plant life, mainly cacti. Large numbers of insects survive this way -- which, in turn, helps the survival of birds. The kangaroo rat can metabolise water from consuming dry seeds.