Their relatives in cooler regions have much shorter ears. New World vultures, such as the Turkey and Black Vultures, are dark in color and thus absorb considerable heat in the desert. But they excrete urine on their legs, cooling them by evaporation, and circulate the cooled blood back through the body. This behavior, called urohydrosis, is shared with their relatives the storks, successful birds of the African deserts. Both vultures and storks may escape the hot midday temperatures of the desert by soaring effortlessly, high on thermals of cooler air.
Many desert animals are paler than their relatives elsewhere in more moderate environments.
Pale colors may be seen in feathers, fur, scales or skin. Pale colors not only ensure that the animal takes in less heat from the environment, but help to make it less conspicuous to predators in the bright, pallid surroundings. The mechanisms some desert animals have evolved to retain water are even more elaborate. They range from simple to physiologically complex. Reptiles and birds excrete metabolic wastes in the form of uric acid, an insoluble white compound, wasting very little water in the process.