The mound-building engineers
On the remote Nicobar Islands, a unique bird has mastered the art of geological engineering. The Nicobar megapode (Megapodius nicobariensis) does not incubate its eggs with body heat. Instead, it constructs enormous mounds of soil, sand, and decaying vegetation. These structures are natural incubators, using heat from either microbial decomposition or, in some cases, geothermal vents and sun-warmed sand. The islands are part of a tectonically active zone, providing the underlying geothermal heat that the birds can exploit.
A male megapode is the primary architect and caretaker of the mound. These mounds can be immense, with some reaching volumes of over 10 cubic meters. The bird's primary task is to maintain a stable internal temperature, which is ideally between 32°C and 35°C. It uses its large feet and beak—thought to be sensitive to temperature to constantly monitor the mound's core. By adding or removing layers of sand and vegetation, the male meticulously manages the heat generated by the compost or the ground, and the eggs develop under precise conditions. A female lays between 4 and 10 large, pinkish eggs in the mound over a period of weeks.