The Mountain Bluebird 
No. 153 
Mountain Bluebird 
A. O. U. No. 768. Sialia currucoides (Bechstein). 
Synonym.— Arctic Bluebird. 
Description. — Adult male in summer: Above rich cerulean blue (quite variable, 
light cerulean blue to Bradley’s blue), palest (cendre blue) on forehead, brightest on 
upper tail-coverts, darkest (spectrum blue) on lesser wing-coverts; below pale blue 
(cendre blue) on chest, shading on sides of head and neck to color of back, paling on 
lower belly, crissum, and under tail-coverts to whitish; exposed tips of flight-feathers 
dusky. Bill and feet black; iris dark brown. Adult male in winter: Blue somewhat 
duller, and feathers skirted more or less with brownish above and below, notably on 
hind-neck, upper back, breast and sides. Adult female: Like male, but paler blue; 
clear on rump, tail, and wings only; elsewhere quenched in gray; pileum, hind-neck, 
back, and scapulars mouse-gray, tinged with greenish blue; outer edge of first primary 
and outer web of outermost rectrix, basally, white; a whitish orbital ring; underparts 
tinged with pale brownish gray, fading to white posteriorly. Young birds somewhat 
resemble the adult female, but are darker and duller (benzo brown); the blue of rump 
and upper tail-coverts is replaced by ashy gray; the back is faintly streaked with white; 
the throat and jugulum are pale gray, indistinctly streaked with whitish; breast, sides, 
and flanks chiefly drab (benzo brown), each feather having a white center. Length 
177.8 (7.00) or over; wing 117 (4.60); tail 72 (2.83); bill 13.4 (.53); tarsus 22.6 (.89). 
Recognition Marks.— Sparrow size; azure blue coloration of male, and bluish 
gray and azure of female unmistakable. 
Nesting. — Nest: Much as in preceding species. Eggs: Usually 5 (6 and 7 of 
record); uniform pale bluish green, sometimes very light bluish white, rarely pure white. 
Av. size 21.6 x 16 (.85 x .63). Season: May-June; two broods. 
General Range. —Mountain districts of western North America, north to 
southern Yukon and northwestern British Columbia; breeding eastward to central 
Saskatchewan, the Black Hills, and western Texas; westward to the Cascade-Sierras; 
southward to the higher ranges of Arizona, New Mexico, and Chihuahua; in winter 
irregularly eastward upon the Great Plains, and southward to southern California, 
Lower California, and Sonora. 
Distribution in California. —A common breeder in the Boreal zones of the 
higher mountains, including the desert ranges; south to the San Bernardino Mountains. 
Occurs in the Warner Mountains, on Mt. Shasta, and upon the inner, more arid portions 
of the northern coastal ranges. Winters irregularly at the lower levels, except in the 
humid sections. 
Authorities.—Gambel ( Sialia arctica), Proc. Acad. Nat. Sci. Phila., vol. iii., 
1846, p. 113; C. H. Townsend, Proc. U. S. Nat. Mus., vol. x., 1887, p. 232 (Mt. Shasta, 
etc.; breeding habits); Ray, Auk, vol. xx., 1903, p. 193 (Lake Valley, breeding); Willett, 
Pac. Coast Avifauna, no. 7, 1912, p. 109 (status in s. Calif.); Tyler, Pac. Coast Avifauna, 
no. 9, 1913, p. 109 (Fresno; winter habits; dates of arrival and departure). 
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