At Santa Cruz he found them even more confiding than the Eastern species, building their nests even in the noisiest streets. One brood came every day during the grape season, at about noon, to pick up grape-skins thrown out by his door, and was delightfully tame, sitting fearlessly within a few feet of the open window.
In regard to their song Mr. Ridgway states that he did not hear, even during the pairing season, any note approaching in sweetness, or indeed similar to, the joyous spring warble which justly renders our Eastern Bluebird (S. sialis) so universal a favorite.
The two Western species of Sialia, though associating during the winter in the region along the eastern base of the Sierra Nevada, are seldom seen together during the breeding-season; the S. arctica returning to the higher portions of the thinly wooded desert mountains, while the S. mexicana remains in the lower districts, either among the cottonwoods of the river valleys or among the pines around the foot-hills of the Sierra.
ROCKY MOUNTAIN BLUEBIRD.
Erythraca (Sialia) arctica, Swains. F. B. A. II, 1831, 209, pl. xxxix. Sialia arctica, Nuttall, Man. II, 1832, 573.—Baird, Birds N. Am. 1858, 224; Rev. 64.—Sclater, Catal. 1861, 11, No. 67.—Dresser, Ibis, 1865, 478. (Texas, winter, very abundant.)—Cooper, Birds Cal. 1, 29. Sialia macroptera, Baird, Stansbury’s Rept. 1852, 314 (larger race with longer wings).
Sp. Char. Greenish azure-blue above and below, brightest above; the belly and under tail-coverts white; the latter tinged with blue at the ends. Female showing blue only on the rump, wings, and tail; a white ring round the eye; the lores and sometimes a narrow front whitish; elsewhere replaced by brown. Length, 6.25; wing, 4.36; tail, 3.00. (1875.)
Young. Male birds are streaked with white, as in S. sialis, on the characteristic ground of the adult.
Hab. Central table-lands of North America, east to mouth of Yellowstone. One individual collected at Fort Franklin, Great Bear Lake. Not common on the Pacific slope; the only specimens received coming from Simiahmoo, Fort Crook, and San Diego. Not recorded as found in Mexico. W. Arizona, Coues.
As already stated, the blue of this species is greener, more smalt-like than in sialis. The females are distinguished from those of the other species by the greener blue, entire absence of rufous, and longer wings.