Like other reptiles, the desert tortoise is cold-blooded. To survive in the desert, the tortoise estivates (remains underground in its burrow) during the hottest times of the day in the summer and hibernates (sleeps underground in its burrow) through the winter. Tortoises come out in the spring to eat grasses and wildflowers and drink water from the spring rains (although they obtain most of their water from the plants they eat). They store water within themselves and use it through the dry months while water is not available. In the spring, they socialize and look for mates. At other times of the year they are less active above ground.