Desert environments produce extreme conditions for survival of animals, just as for plants (Chapter 3). High temperature and low water availability make thermoregulation an acute problem during the summer, whereas cold temperatures and low food availablility during winter make aboveground activity energetically inefficient for most desert animals. Lack of water presents special problems for animals that produce liquid excreta, and these osmotic difficulties are magnified when diets contain materials that are high in solutes. Nutrient resources, be they plant tissues for herbivores or prey for carnivores, are often low in abundance and poor in quality, and individual food items tend to be available only for short intervals. Moreover, coexisting species must share those limited resources. Consequently, each resident species must have a set of adaptations to cope with stresses during its lifetime, and desert animals, like plants, utilize physiological, morphological, and phenological adaptations to either tolerate or avoid stresses. Unlike plants, however, animals have the ability to alter their environment through movement and thus possess intriguing suites of behavioral adaptive responses.

HEAT BALANCE AND THERMOREGULATION

Problems of heat in deserts

Strategies for maintaining reasonable

Consequently, each resident species must have a set of adaptations to cope with stresses during its lifetime, and desert animals, like plants, utilize physiological, morphological, and phenological adaptations to either tolerate or avoi stresses. Unlike plants, however, animals have the ability to alter their environment through movement and thus possess intriguing suites of behavioral adaptive responses. Strategies for maintaining reasonable thermal balance are of critical importance for ecological success of each animal species in a desert environment, especially the hot, dry conditions of summer months in the Mojave Desert, where midday temperatures commonly exceed 40°C and the ground surface may heat up to 70°C from intense solar radiation.