The group has a wide geographical range, occurring in Europe, Africa, Madagascar, South Asia, the Indian Archipelago, and Australia.
The Hoatzin.
This bird is one of the puzzles of the ornithologist. Its pedigree is still a mystery, but it is generally believed to have some relation to the Game-birds. Its whole life is passed in trees overhanging water, and its flight restricted to short journeys from tree to tree. In South America, its home, it is known by a variety of names, one of which means Stinking-pheasant. This is in allusion to the peculiar odour of its flesh, which smells, according to some, like musk, and to others like raw hides. Another remarkable feature of this bird is the fact that it has turned its crop into a sort of gizzard, whilst the true gizzard, having been relieved of its functions, has diminished to the size of a hazel-nut. The unusual purpose to which the crop has been put has brought about considerable modification in the form of the breast-bone, which is quite different to that of any other bird.
Photo by J. W. McLellan] [Highbury.
HOATZIN.
This is a native of the Amazons Valley, and lives entirely in the trees.
The young of these birds are quite as remarkable as the parents, for almost as soon as they are hatched they crawl out of the nest, along the boughs of the tree in which it rests, to meet the parents coming with food. In these crawling excursions they are aided by the wings, which for a time serve as fore feet. The thumb and first finger are armed with strong claws, with which a firm hold is gained on the bark of the tree. To render these claws effective so long as they are necessary, the quill-feathers of the tip of the wing have their development checked till the others have grown long enough to serve the purposes of flight.
The Rails.
The Rails are all water-loving birds, dwelling in swamps or on the borders of lakes and streams. Although all swim easily, none have webbed feet. The flight is weak; several species, indeed, have lost this power altogether. The body is much compressed, enabling them to pass readily through the narrow interspaces of dense aquatic foliage. The Rails appear to be related on the one hand to the Game-birds, and on the other to the Cranes. In size they vary from a bird as large as a fowl to one as small as a lark.