Under parts white, faintly tinged with rusty posteriorly; each feather spotted with black, excepting on the immaculate chin. These spots are rather larger and more quadrate on the jugulum, where they are sometimes on the sides of the feathers (on one or both sides); posteriorly, however, they are elongated or tear-shaped, and strung along the shaft, one or two on each. On the crissum they are large and much rounded, three or four on each longer feather. Legs rather dusky. Bill lead-color, pale at the base below; iris reddish-brown. A broad white stripe from bill over the eye and nape; edged above and below with black; line behind the eye like the crown; cheek-feathers white, edged with blackish.
Immature specimens exhibit a tendency to a whitish spotting in the ends of the feathers of the cap. A very young bird does not, however, differ materially, except in having the spots less distinct beneath, the white streaks less conspicuous above, the white of the wings soiled with rufous. Specimens vary considerably in the proportional as well as absolute thickness and length of the bill; thus, No. 32,167 measures .80 from nostril to end of bill, instead of .60, as given below for No. 12,965.
12,965. Total length, 7.50; wing, 3.30; tail, 3.40; its graduation, .45; exposed portion of first primary, 1.42, of second, 2.15, of longest, or fourth (measured from exposed base of first primary), 2.45; length of bill from forehead, .90, from nostril, .60; along gape, 1.07;
tarsus, 1.02; middle toe and claw, .90; claw alone, .25; hind toe and claw, .76; claw alone, .35.
Hab. Only observed at Cape St. Lucas, Lower California.
This species is most nearly allied to C. brunneicapillus; the most apparent difference at first sight being in the greater concentration of black on the throat and jugulum in brunneicapillus, and the much smaller size of the remaining spots on the under parts, with the decided light-cinnamon of the posterior portion of the body. The outer and central tail-feathers alone are marked as in C. affinis, the intermediate ones being entirely black, with the exception of a white subterminal band.
This is one of the most characteristic birds constituting the isolated fauna of Cape St. Lucas. Like nearly all the species peculiar to this remarkable locality, it is exceedingly abundant, breeding in immense numbers. It has not yet been detected elsewhere, though it may possibly be found on the Lower Colorado.
Habits. This recently described species was first discovered by Mr. Xantus, and has, so far as is known, a somewhat restricted locality, having been met with only at the southern extremity of Lower California, where it is an exceedingly abundant bird. Mr. Xantus has published no observations in regard to its habits, which, however, are probably very nearly identical with those of the more common species. From the brief memoranda given by him in the general register of his collections, made at Cape St. Lucas, we gather that their nests were built almost exclusively in opuntias, cacti, and the prickly pear, and were generally only four or five feet from the ground, but occasionally at the height of ten feet.
The nests are large purse-shaped collections of twigs and coarse grasses, very similar to, and hardly distinguishable in any respect from, those of the more northern species. The eggs vary from 1.05 to 1 inch in length, and from .65 to .70 of an inch in breadth, and have a reddish-white ground very uniformly dotted with fine markings of reddish-brown, purple, and slate.
Subgenus SALPINCTES, Cabanis.