Sp. Char. (No. 18,322 ♂.) Top of head glossy black, with greenish lustre; back and scapulars similar, but rather duller, and somewhat streaked by the appearance of the white sides of the feathers,—the bases of the feathers, however, being plumbeous. Chin, throat, and sides of head, chestnut-brown, this extending round on the nape as a distinct continuous collar, which is bounded posteriorly by dull grayish. The chestnut darkest on the chin, with a rich purplish tinge. Rump above and on sides paler chestnut (sometimes fading into whitish). Upper tail-coverts grayish-brown, edged with paler, lighter than the plain brown of the wings and tail. Forehead, for the length of the bill, creamy-white, somewhat lunate, or extending in an acute angle, a little over the eye; a very narrow blackish frontlet; loral region dusky to the bill. A patch of glossy black in the lower part
of the breast, and a few black feathers in the extreme chin, the latter sometimes scarcely appreciable. Under parts dull white, tinged with reddish-gray on the sides and inside of the wings. Feathers of crissum brownish-gray, edged with whitish, with a tinge of rufous anteriorly (sometimes almost inappreciable). Nest of mud, lined; built against rocks or beams; opening sometimes circular, on the side; sometimes open above; eggs spotted.
Total length, 5.10; wing, 4.50; tail, 2.40, nearly even; difference of primary quills, 2.10; length of bill from forehead, .38, from nostril, .25, along gape, .60, width, .50; tarsus, .48; middle toe and claw, .72; claw alone, .22; hind toe and claw, .44; claw alone, .20.
Hab. Entire United States from Atlantic to Pacific, and along central region to Arctic Ocean and Fort Yukon; Panama in winter. Not noted at Cape St. Lucas, in Mexico, or in West Indies.
There is no difference between the sexes, but the young bird is very different from the adult in the following particulars: the steel-blue above is replaced by a lustreless dusky-brown, the feathers (except on head) being margined with a creamy tint; the neck merely tinged with rufous; the throat has only a dusky suffusion, and the chin is much mixed with white; the frontal patch is obsolete.
A closely allied species from Mexico, P. swainsoni (see Baird, Rev. Am. Birds, 1865, 290), possibly yet to be found near our southern border, differs as follows:—
Frontlet reddish-white, with narrow band of black along upper mandible lunifrons.
Frontlet chestnut-brown, without black at base of upper mandible. Size smaller swainsoni.
Sometimes (as in 11,027 ♀ and 11,025 ♂, Fort Bridger) the black patch extends upward, somewhat broken, however, to the bill.
Habits. The early history of the Cliff Swallow must always remain involved in some obscurity, so far as concerns its numbers and distribution before the first settlement of the country, and even down to the early portion of the present century. Its existence was unknown to Mr. Wilson, and it was unknown to other naturalists until obtained by Say, in Long’s expedition to the Rocky Mountains in 1820. It is now known to occur nearly throughout North America, and to breed from Pennsylvania to the Arctic regions, and from the Atlantic to the Pacific. Yet to many parts of the country it is a new-comer, where, a few years since, it was entirely unknown. It seems to be probable that at first this species was to be found only in certain localities that offered favorable places whereon to construct their nests. Where high limestone cliffs abound, these birds may have always occurred, although escaping observation.