But mallee-fowl use a different system entirely. During the winter, the male mallee-fowl excavates a hole in the ground. Astonishingly, this hole can measure four feet deep and twelve feet across. It then proceeds to fill this hole with every scrap of vegetation in the area and covers it with a layer of sand. The moist, warm vegetation begins to decompose.
Bacteria eat away at the organic material.
As a result of this process, heat is given off, and the incubator begins to warm up. Now it is ready to receive eggs. The female mallee-fowl arrives, digs a hole in the litter, and lays her eggs. The male mallee-fowl then covers the area with a mound of earth that can measure up to fifteen feet high and thirty feet across. Organic matter produces heat as a by-product of its decomposition.