Another class of birds that have a fancy for big dome-like nests are the mound-birds. We find them in Australia, the Philippines, and the islands of the South Seas. Their scientific nickname is _Megapoddidae_, the "big-footed." It's with their big feet that they pile immense heaps of leaves, twigs, and rotten wood over their eggs. And what for, do you suppose? To hatch them! This heap of material not only absorbs the heat of the sun, but, in decaying, makes heat of its own. These mounds, of course, contribute tons and tons of fertilizer to the soil, but what interests the birds is that these warm heaps hatch their eggs. It's a kind of an incubator system, you see. As it is with many tens of thousands of our own little chickens, these days, the baby megapodes are born orphans. That heap of dead sticks, leaves, and earth is all the mother they ever know. As soon as the mother birds have laid their eggs in the mounds and covered them up, they go off gossiping with other lady megapodes, and don't bother their heads any more about their babies. WHY LITTLE BIG FOOT NEVER SAYS "MAMMA" But it really doesn't seem to matter. It's more of a question of sentiment than anything else, for the babies get on very well by themselves. When the time comes they not only make their own way out of the shell, as all birds do, but they work their way up through the rubbish-heap and run off at once into the woods to hunt something to eat. It's all right, after all, I suppose; but if _I_ were a little mound-builder's baby, I'd rather have a mamma that would stay around and go places with me, wouldn't you? There's one nice thing about these mamma mound-builders, though; they're so neighborly and sociable. It's like a regular old-fashioned quilting party to see them build a nest. The birds look like turkeys, and one of the species is called the "brush turkey," but they are no bigger than an ordinary chicken--than a rather small chicken, in fact. When I tell you, then, that these mounds of theirs are often six feet high and twelve feet across in the widest part, the middle, you can see it takes good team-work to put them up. [Illustration: BRUSH TURKEYS BUILDING THEIR INCUBATORS It's like an old-fashioned quilting party--the co-operative mound building of the brush turkeys. The text tells you about that back kick of theirs.]