I copied this excerpt from Author: Lanny and Marilyn Johnson
“The Mallee Fowl is a mound building bird that only lives in Austria. It is about the size of a chicken and is an incredibly busy worker. In the fall of each year the male begins to dig a hole about three feet deep. After the hole is dug, he piles leaves and twigs into the pit. After each rain he covers a layer of vegetation with sand sealing in the moisture. The mounds he builds can be up to 35 feet across and 15 feet high. He will move as much as 6000 pounds of material to build his mound! As the wet vegetation decays, it produces heat. So as the leaves and twigs rot, the pile warms up. “… To read the whole article Only God Can Make An Instinct
Some more links about the Mallee Fowl: