BLACK-CAPPED GNATCATCHER.
Culicivora atricapilla, Lawrence, Ann. N. Y. Lyc. V, Sept. 1851, 124 (not of Swainson). Culicivora mexicana, Cassin, Illust. I, 1854, 164, pl. xxvii (not of Bon.). Polioptila melanura, Lawrence, Ann. N. Y. Lyc. VI, Dec. 1856, 168.—Baird, Birds N. Am. 1858, 382; Review, 68.—Heermann, P. R. R. R. vol. X (Williamson), 1859, 39.—Cooper, Birds Cal. 1, 37.
Sp. Char. Above plumbeous-blue. Whole crown, to bill and eyes, with tail, lustrous blue-black. Beneath pale bluish-gray, almost white on chin and anal region; the flanks and crissum tinged with brown. Edge of eyelids, and margin and tip of outer web of first and second lateral tail-feathers, white. Female and young without the black of the crown. Length, 4.15; wing, 1.85; tail, 2.10.
Hab. San Diego to Fort Yuma and Cape St. Lucas. Arizona, Coues.
Specimens of this species from Cape St. Lucas differ from those of San Diego described in the P. R. R. Report (7,191) in having the whole of the outer web of the outer tail-feather white, and in a rather larger white tip. The colors beneath are a little less ashy, though not of a pure white. The ash of the back is rather lighter and purer. The lores are rather lighter. The first primary is a little larger and broader.
It is possible that the restriction of the white of the outer web of the exterior tail-feather to the outer half only is an unusual circumstance, as both Mr. Cassin and Mr. Lawrence, in their descriptions, speak of the entire outer web being white,—the second feather being of the former character. Under these circumstances there will be little specific difference between the tails of P. melanura and plumbea. The female birds will then be separated by the light superciliary line and much shorter tarsi of P. plumbea,—the latter measuring .63 instead of nearly .70 of an inch.
Habits. This species was first noticed as belonging to the North American fauna by Captain McCown, who obtained it near Ringgold Barracks in 1850. It has since been noticed at Fort Yuma and at San Diego, and obtained in greater abundance at Cape St. Lucas. It is also found in Mexico. Dr. Cooper says that it is common all winter both at San Diego and at Fort Mohave. It has been traced as far north as latitude 30° in the Sierra Nevada. Its song he describes as a harsh ditty of five parts, something like a wren’s song, with notes like those of a swallow, and also closely resembling the song of Vireo belli. Their scolding note is a faint mew, like that of a cat.
The habits of this species appear to be not unlike those of the peculiar family to which it belongs. All its members are among our smallest birds, are almost exclusively inhabitants of woods, and resemble the Reguli in their restless activity in pursuit of the smallest insects on which they feed. This bird is described as particularly active, quick in its movements, searching
with great activity for its food, and preferring low trees and bushes. At times it will dart about in the air in pursuit of small insects.