Mound bird, any of 12 species of birds in the megapode family. Found from Australia westward to the Nicobar Islands, this bird is also known as mound builder or incubator bird because of the mound in which it incubates its eggs. The male uses his large feet to heap plant matter into a mound, which may take up to 11 months to build; the female lays her eggs in it, and then covers them with more matter. As the materials in the mound decay, they release heat. That and the heat of the sun keep the mound warm, and the eggs hatch in 6–7 weeks. Mound birds use the same mound year after year, adding to it each time. A mound can become as large as 14 ft (4 m) high and 70 ft (21 m) across.