oss or grasses, lined with hair or feathers, and during May lay
from four to six pale greenish blue eggs; size .90 x .60.

[Illustration 450: Greenish blue.]
[Illustration: Wheatear.]
[Illustration: Pale greenish blue.]
[Illustration: left hand margin.]

Page 449

[Illustration 451: BLUEBIRD.]

Page 450

766. BLUEBIRD. _Sialia sialis sialis._

Range.--Eastern United States, breeding from the Gulf to southern
Canada. Winters in the southern half of the United States.

These familiar birds build in cavities in trees, usually below 20 feet
from the ground, crevices among ledges, bird boxes and in any suitable
nook they may discover about buildings, providing that English Sparrows
do not molest them. They raise several broods a year, commencing in
April when they lay from three to six pale bluish white eggs (rarely
pure white); size .80 x .60. The cavities of their nesting sites are
lined with grasses and feathers usually, although I have found the eggs
on the unlined bottom of cavities in trees.

766a. AZURE BLUEBIRD. _Sialia sialis fulva._

Range.--This pale variety is found in southern Arizona and southward.

Its nesting habits are the same and the eggs are indistinguishable from
the last.

767. WESTERN BLUEBIRD. _Sialia mexicana occidentalis._

Range.--Pacific coast from Lower California to British Columbia.

The Western Bluebird is as common and familiar in its range as the
common Bluebird is in the east. It nests in similar locations and its
eggs are scarcely distinguishable, although averaging a trifle darker in
shade; size .80 x .60.

767a. CHESTNUT-BACKED BLUEBIRD. _Sialia mexicana bairdi._

Range.--Rocky Mountain region from Mexico to Wyoming.

The nesting habits or eggs of this brighter colored bird do not differ
from those of the last species.

767b. SAN PEDRO BLUEBIRD. _Sialia mexicana anabelae._

Range.--San Pedro Martir Mountains in Lower California.

The eggs of this variety will not in all probability be any different
from those of the preceding Bluebirds.

768. MOUNTAIN BLUEBIRD. _Sialia currucoides._

Range.--Rocky Mountain region, breeding from New Mexico north to Great
Slave Lake; winters in southwestern United States and Mexico.

This azure blue species is common in the greater part of its range and
is found west to the Sierra Nevadas in California. Like the eastern
Bluebird they nest in holes in trees or anywhere that they can find a
suitable cavity or crevice. T