The nesting habits of birds are varied. Gulls drop eggs on bare ground or rocks; the Baltimore Oriole and Tailor bird construct hanging nests of elaborate workmanship; the Woodpecker hews out a deep nest in a rotten limb; the Kingfisher digs one out of a sandy bank, while the Cuckoo takes possession of the nest of some other bird. Most birds select nesting places away from other species, but Swallows, English Sparrows, Grackles, and Crows live in communities. There are between seven and eight thousand species of living birds. A few species have become extinct, specimens of which it is the intention of BIRDS to present in future numbers. There are three centers of distribution in the United States: (1) the Atlantic states and Mississippi valley; (2) the Rocky Mountain plateau; (3) the Pacific coast. Most of the birds breeding in the northern portions of the United States migrate south during the winter months. Those remaining are known as residents. THE IVORY-BILLED WOODPECKER. In size, though hardly in beauty, this is indeed the prince of Woodpeckers, the largest of our North American species. Its length ranges from nineteen to twenty-one inches. There is one other Woodpecker, called the Imperial, which is larger, measuring twenty-three or twenty-four inches in length. This bird is found in Western Mexico, north along the Sierra Madre, and probably, according to Davie, has not yet been observed within the limits of the United States. The Ivory-billed is now rare, and is apparently restricted to the extreme southern states, especially those bordering the Gulf of Mexico. It is of a wild and wary disposition, making its home in the dark, swampy woodlands. The dense cypress swamps of Florida are one of its favorite haunts. The nest of the Ivory-bill is excavated in a tree, about forty feet from the ground, the cavity often being nearly two feet in depth. Three or more eggs are laid. This bird does not remain long in one place, and during the day ranges over an extended territory. Its call is a high, rather nasal, _yap-yap-yap_, sounding in the distance like the note of a penny trumpet. To use the language of Chapman, whose "Handbook" is a mine of ornithological knowledge, Woodpeckers are rather solitary birds, but are sometimes found associated in scattered companies during their migrations. Above all other birds, they are especially adapted to creep or climb. The peculiar structure of the foot, with its two toes directed forward and two backward, except in one genus, the Three-toed (which will appear in the April number of BIRDS), assists them in clinging to an upright surface, while the pointed, stiffened tail feathers serve as a prop when the bird is resting. The stout, chisel-like bill is used to cut away wood and expose the hiding places of grubs, etc., when the long, distensible tongue, with its horny, spear-like tip is thrust in, the food impaled and drawn out.