TUBDID^ — SAXIGOLIN^ : BL UE-BIRDS. 
257 
olive-brown, superciliary line, edges of wings and tail, and all under parts, cinnamon-brown ; 
tail black and white as in the adult. Length of $ 6.75 ; extent 12.50; wing 3.75 : tail 2.50 ; 
tarsus 1.00; middle toe and claw 0.75. 9 smaller: length 6.50; extent 11.50, etc. Atlantic 
coast, from Europe via Greenland ; also North Pacific and Arctic coast, from Asia. Common 
in Greenland, and probably also breeds in Labrador. Nest in holes in the ground or rocks, 
crevices of stone walls, etc. ; eggs 4-7, 0.87-0.60, greenish-blue, without spots. 
7. SIA'LIA. (Gr. o-taXi's, sMiS, a kind of bird.) Blue-birds. Primaries 10, the 1st spurious 
and very short. Wings pointed, the tip formed by the 2d, 3d, and 4th quills. Tail much 
shorter than wings, emarginate. Bill about half as long as head or less, straight, stout, wider 
than deep at base, compressed beyond nostrils, notched near tip, the culmen at first straight, 
then gently convex to the end, gonys slightly convex and ascending, commissure slightly 
curved throughout. Nostrils overhung and nearly concealed by projecting bristly feathers ; 
lores and chin likewise bristly. Gape ample, the rictus cleft to below the eyes, furnished 
with a moderately developed set of bristles reaching about opposite the nostrils. Feet short, 
though rather stout, adapted exclusively for perching (in Saxicola the structure of the feet 
indicates terrestrial habits). Tarsus not longer than the middle toe; lateral toes of unequal 
lengths ; claws all strongly curved. Blue is the principal color of this beautiful genus, which 
contains three species. They are strictly arboricole ; frequent the skirts of woods, coppices, 
waysides, and weedy fields ; nest in holes, and lay whole-colored eggs ; readily become semi- 
domesticated, like the swallow, house wren, and house sparrow; feed upon insects and berries; 
and have a melodious warbling song. Polygamy is sometimes practised by them, contrary to 
the rule among Oscines. Blue-birds are peculiar to America, and appear to have no exact 
representatives in the other hemisphere. 
Analysis of Species. 
$ Rich sky-blue, uniform on back ; throat and breast chestnut, belly white sialis 27 
(5 Rich sky-blue, including throat ; middle of back and breast chestnut, belly whitish . . . . mexicana 28 
S Light blue, paler below, fading to white on belly ; no chestnut arctica 29 
27. S. si'alis. (Gr. o-iaX is, siaZzs, a kind of bird. Fig. 131.) Eastern Blue-bird. Wilson's 
Blue-bird. ^, in full plumage: Rich azure-blue, the ends of tlie wing-quills blackish; 
throat, breast, and sides of the body chestnut; belly and 
crissum white or bluish-white. The blue sometimes ex- 
tends around the head on the sides and often fore part of 
the chiu, so that the chestnut is cut ofi" from the bill. 
Length 6.50-7.00; extent 12.00-13.00; wing 3.75-4.00; 
tail 2.75-3.00; bill 0.45; tarsus 0.70. $, in winter, or 
when not full-plumaged : Blue of the upper parts inter- 
rupted by reddish-brown edging of the feathers, or obscured 
by a general brownish wash. White of belly more ex- 
tended ; tone of the other under parts paler. In many 
Eastern specimens, the reddish-brown skirting of the 
feathers blends into a dorsal patch ; when this is accom- 
panied by more than ordinary extension of blue on the I3i. — Blue-bird, nat. size. (Ad 
throat they closely resemble S. mexicana. 9 > f^^H ^' ^'^ 
plumage: Blue mixed and obscured with dull reddish-brown; becoming bright and pure on 
the rump, tail, and wings. Under parts paler and more rusty-brown, with more abdominal 
white than in the male. Little smaller than Young, newly fledged: Brown, becoming 
blue on the wings and tail, the back sharply marked with shaft-lines of whitish. Nearly 
all the under parts closely and uniformly freckled with white and brownish. A white ring 
round the eye ; inner secondaries edged with brown. From this stage, in which the sexes arc 
indistinguishable, to the perfectly adult condition, the bird changes by insensible degrees. 
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