BIRDS — TUEDIDAE — SIALIA MEXICAN A. 223 
SIALIA MEXICANA, Swain son. 
Western Blue Bird. 
Sialia mexicana, Sw. F. Bor. Am. II, 1831, 202. 
Sialia occidentalis, Townsend, Jour. Ac. Nat. Sc. VII, n, 1837, 188.— Ib. Narrative, 1839, 343.— Aud. Synopsis, 
1839.— Ib. Birds America, II, 1841, 176; pi. 135.— Nuttall, Man. I, (2d ed.,) 1840, 513.— 
Newberry, Zool. Cal. & Or. Route, 80; Rep. P. R. R. VI, iv, 1857. 
Sylvia occidentalis, Audubon, Orn. Biog. V, 1839, 41 ; pi 393. 
Sialia caeruleo-collis, Vigors, Zool. Beechey 's Voyage, 1839, 18 ; pi. lii. 
S P- Ch. — Bill slender; head and neck all round, and upper parts generally bright azure blue. Interscapular regions, sides 
and fore part of the breast, and sides of the belly, dark reddish brown. Rest of under parts (with tail coverts) pale bluish, 
tinged with gray about the anal region. Female duller above ; the back brownish ; the blue of the throat replaced by ashy 
brown, with a shade of blue. Length, 6.50 ; wing, 4.25 ; tail, 2.90. 
Hub. — Pacific coast North America, and along valley of Gila to upper Rio Grande and south. 
In perfectly mature males the blue of the throat is as bright as that on the crown ; otherwise 
it is duller. There is generally a blackish shade on the cheeks. The blue on the belly is 
always paler. The reddish brown on the back and breast are in the form of lateral patches, 
meeting more or less narrowly on the central line. Sometimes on the middle of the back it 
does not meet at all, and at others it is quite broadly continuous ; the latter is most frequently 
seen in Eocky mountains specimens. The quills and tail feathers are light blue ; the shafts 
black. The exposed tips of the folded quills, however, are black. Bill and feet are black. 
The female is much duller in colors ; the blue most conspicuous on the rump, tail, primaries, 
and wing coverts. The blue of the head is very dull, and there is a broad scapular and inter- 
scapular space strongly overlaid with brownish. The throat and sides of the head are of much 
this same color, shading very insensibly into the reddish brown of the breast. 
The young bird has the tail and wings as in the adult. The head, back, and breast are dull 
brown ; each feather, except on the crown, streaked with white. 
The shade of blue in this species is much as in the common eastern species — only brighter 
and more intense. The bill is more slender, the wings longer ; the combination of the blue of 
the under parts with the brown on the back readily distinguishes it. The females of the two 
species are very similar. They may be distinguished by the brown tinge on the back and the 
blue on the belly and under tail coverts, with the bluish shade on the throat, as well as by the 
slenderer and straighter bill of the western species. The spotted young can only be dis- 
tinguished by the slender bill and bluish belly and under tail coverts. 
Specimens from California occasionally have but little brown on the back, but it is almost 
always distinctly visible. 
