Scrubfowl and their Spectacular Nests
Some bird species build very large nests. The Bald Eagle, for instance, arranges sticks and branches into a giant platform weighing hundreds of pounds. One bald eagle nest that fell from a tree weighed in at 2 tons!
The largest bird nests of all, however, may be those of the megapodes of Australia and New Guinea. These chicken-sized birds use their giant feet (megapode means “great-footed”) to scrape sand, dirt and vegetation into a giant mound on the ground.
The mound-nest of the Scrubfowl, an Australian megapode, can be 15 feet (4 meters) high and an incredible 35 feet (12 meters) wide! Several birds work together to build it; then they bury their eggs several feet deep inside the mound.
In such a huge nest, how can the Scrubfowl possibly keep her eggs warm with her own body heat? The answer is: she doesn’t have to. The mound-nest itself act like a giant incubator.
The birds bury vegetation deep in the mound- they may even let the plants get rained on before covering them up with layers of dirt. As tropical sunshine warms the mound, this buried plant matter ferments, creating plenty of heat. The birds carefully regulate the composting in the mound, keeping its heat at a stable 35-39 degrees Celsius. To cool the mound, they remove layers of dirt; to warm it, they add more vegetation or sun-warmed layers of sand.
Some lucky birds living near volcanoes in New Guinea don’t have to work so hard- they build their nests where volcanic heat can keep their nest warm.
Incubated in this cozy nest, the chicks hatch fully feathered and ready to fly. But first they have to dig their way to the surface, through several feet of dirt – a process that may take several days.