Char. The basal portion of the bill covered by a soft skin, in which are situated the nostrils, overhung by an incumbent fleshy valve, the apical portion hard and convex. The hind toe on the same level with the rest; the anterior toes without membrane at the base. Tarsi more or less naked; covered laterally and behind with hexagonal scales.
The bill of the Columbidæ is always shorter than the head, thinnest in the middle; the basal half covered by a soft skin; the apical portion of both jaws hard; the upper one very convex, blunt, and broad at the tip, where it is also somewhat decurved. There is a long nasal groove, the posterior portion occupied by a cartilaginous scale, covered by a soft cere-like skin. The nostrils constitute an elongated slit in the lower border of the scale. The culmen is always depressed and convex. The bill is never notched in the true Doves, though Didunculus shows well-defined serrations. The tongue is small, soft, and somewhat fleshy.
The wing has ten primaries, and eleven or twelve, rarely fifteen, secondaries; the latter broad, truncate, and of nearly equal length. The tail is rounded or cuneate, never forked.
The tarsus is usually short, rarely longer than the middle toe, scutellate anteriorly, and with hexagonal plates laterally and behind; sometimes naked. An inter-digital membrane is either wanting entirely, or else is very slightly indicated between the middle and outer toes.
The valuable monograph of Bonaparte in the second part of Conspectus Avium renders the task of arranging the American Columbidæ in proper sequence and of determining their synonomy comparatively easy. He divides the family into Lopholæminæ, Columbinæ, Turturinæ, Zenaidinæ, and Phapinæ, the second and fourth alone occurring in North America. They may be briefly distinguished as follows:—
Columbinæ. Tarsus shorter than the lateral toe; feathered above.
Zenaidinæ. Tarsus longer than the lateral toes; entirely bare of feathers.
Subfamily COLUMBINÆ.
Char. Tarsi stout, short, with transverse scutellæ anteriorly; feathered for the basal third above, but not at all behind. Toes lengthened, the lateral decidedly longer than the tarsus. Wings lengthened and pointed. Size large. Tail-feathers twelve.
This section of doves embraces the largest North American species, and among them the more arboreal ones. The genera are as follows:—