Malleefowl (Leipoa ocellata) belong to a small family of birds known as Megapodiidae, the megapodes or 'mound-builders'. The name megapode (mega-pod) is derived from the fact that these birds have unusually large feet and toes, used to dig the soil and gather leaf litter in order to build a nest-mound in which to incubate their eggs. These birds have developed a very unusual method of incubating their eggs using external sources of heat. Megapodes lay their eggs in sand, heated by the sun or geothermal activity, or in mounds of decomposing leaf and vegetable matter (compost). 22 species of megapodes exist in the world today and are confined almost exclusively to the Australasian region.