The Donkey is a domesticated species, descended from this equine, the African Wild Donkey, or Ass. Two subspecies exist, but only 570 individuals are known to survive. Her life is adapted to a dry, desert environment. The large ears are not only sensitive to sound, but also act in thermoregulation. She lives in herds, lead by a dominant male, although other males are tolerated. Each herd holds a large territory, the male marking the boundaries with his dung. Due to their open and sparse environment, herds may become quite spread out and they communicate with one another making loud braying calls. Her diet mostly consists of dry grass, bark and leaves; despite having a tough digestive system she does need to drink every two-three days.