Why Does This Bird Build a Big Mound?

The Mallee fowl builds a mound so that its eggs will hatch . The male makes a very large mound out of dead leaves, sand and earth. Then the female lays eggs in the mound. As the leaves rot they produce heat, keeping the eggs warm so they will hatch. Mallee fow, which are distributed over Indonesia, New Guinea and Australia, do not use their own body heat to incubate their eggs. In the case of the Australian red Mallee fowl, the male builds a huge mound that serves as an incubator. He begins in the autumn, digging a hole about 10 feet (3 m) in diameter and three feet (.9 m) deep, then putting fallen leaves in it. Gradually the leaves decompose to form a compost that generates heat. In the early spring the male digs a hole in the top of the heap of compost and adds new leaves to make a burrow. About a month later the female lays eggs there and the male covers them with sand. During the 90 days before the eggs hatch the male monitors the mound's interior temperature which he maintains at a constant 91 degree Fahrenheit. (33 degree Celsius) by adjusting the sand's thickness.