Adaptations of birds for life in deserts with particular reference to Larks (ALAUDIDAE)

Abstract

Birds inhabit all deserts, an unusual observation because they are mainly diurnal, non-fossorial, and have the highest mass-specific metabolism of all vertebrates. Many of the “adaptations” of birds for life in deserts are thought by some to be intrinsic in all birds, and thus have been considered to be pre-adaptations. Nevertheless, recent evidence suggests that desert birds do differ from birds of more mesic habitats, and physiological adaptations include reductions in basal metabolism and cutaneous water loss. Behavioural mechanisms that permit a desert existence include nomadism, enabling them to move away from low resource patches to more productive patches, and the ability to use features of their environment to escape from high temperatures. Desert birds can prevent overheating by using rodent burrows and other shelters during the heat of the day. Birds in deserts include a high proportion of ants in their diet, a resource not often exploited by birds of more temperate environments, and they also show seasonal or opportunistic shifts in their diet, feeding on seeds when available, and on more succulent green plant matter, such as leaf bases of grasses, after rain. Certain taxa, for example sandgrouse (Pteroclidae) and larks (Alaudidae), are mainly found in deserts. The adaptations in some species of larks are discussed in detail.