These things ferment and decompose, producing heat in the process. And the funny thing was that I wasn't just using a figure of speech. A little bird really had taught me the explanation. Mallee-fowl are a group of birds found from Malaya to Australia. The extraordinary thing about mallee-fowl, however, is not their feet, but the way in which they incubate their young.
Birds lay eggs, and eggs have to be kept warm.
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.