The North American species of Kingfisher belong to the subfamily Cerylinæ, characterized by the crested head, and the plumage varying with sex and age. The single genus Ceryle includes two types, Streptoceryle and Chloroceryle.
Genus CERYLE, Boie.
Ceryle, Boie, Isis, 1828, 316, ch. (Type, Alcedo rudis of Africa.)
Ispida, Sw. Birds, II, 1837, 336. (Type, A. alcyon, in part.)
Gen. Char. Bill long, straight, and strong, the culmen slightly advancing on the forehead and sloping to the acute tip; the sides much compressed; the lateral margins rather dilated at the base, and straight to the tip; the gonys long and ascending. Tail rather long and broad. Tarsi short and stout.
This genus is distinguished from typical Alcedo (confined to the Old World) by the longer tail, an indented groove on each side the culmen, inner toe much longer than the hinder instead of equal, etc.
The two species of North American Kingfishers belong to two different subgenera of modern systematists, the one to Streptoceryle, Bonap., the other to Chloroceryle, Kaup. The characters of these subgenera are as follows:—
Streptoceryle, Bonap. (1854). Bill very stout and thick. Tarsus about equal to the hind toe; much shorter than the inner anterior. Plumage without metallic gloss; the occipital feathers much elongated, linear, and distinct. Type, C. alcyon.
Chloroceryle, Kaup (1849). Size smaller and shape more slender than in
the preceding. Bill long, thin. Tarsi longer than hind toe; almost or quite as long as the inner anterior. Plumage with a green metallic gloss above; the occiput with a crest of rather short, indistinct feathers. Type, A. amazona.