All of the grouse, quails, and introduced partridges of North America share a number of anatomical traits which provide the basis for their common classification within the order Galliformes. Among these are the facts that they all have fowl-like beaks and four toes. In all the North American species the hind toe is elevated and quite short, thus is ill-adapted for perching. There are always ten primaries, thirteen to twenty-one secondaries, and twelve to twenty-two tail feathers (rectrices). Aftershafts on the contour feathers are well developed, especially in the grouse, and true down feathers are infrequent. A large crop is present, and is associated with the largely granivorous (seed-eating) behavior of most quails, and the more generally herbivorous (leaf-eating) diets of grouse. The egg colors range from pastel or earth tones (buff, cream, olive, etc.) to white, with darker spotting prevalent among those species having nonwhite eggs. The nest is built on the ground, and incubation is by the females alone or occasionally by both sexes (some quails and partridges). The young are down-covered and precocial and are usually able to fly short distances in less than two weeks. They are cared for by the female (most grouse) or by both parents (some ptarmigans, all quails). A number of external structural characteristics typical of grouse, quails and partridges are shown in figures 3 and 4.
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