330 
BIRDS OF PENNSYLVANIA. 
Genus SIALIA Swainson. 
Sialia sialis (Linn.) 
Bluebird. 
Description (Plate 50, adults and young'). 
Length about 62 ; extent about 12^ inches ; bill and legs blackish ; iris brown. 
Adult Male, in summer. — Upper parts uniform azure blue, sides of head, and fore 
part of chin, blue ; throat, breast and sides reddish-brown ; abdomen, anal region 
and under tail-coverts, white. 
Male, in fall and winter. — Blue duller, feathers of the head, neck and back edged 
with rusty ; white on abdomen more extended ; the reddish-brown or chestnut on 
the throat and breast is darker. 
Adult female. — Upper parts dull grayish-blue, brightest on rump, tail and wings ; 
lower parts similar to male but much duller. The young, in first plumage, have 
wings and tail only blue ; top of head and upper parts are grayish or brownish 
(usually the latter color), middle of back more or less streaked with white ; lower 
parts are whitish (clearest on chin and abdomen) ; throat, breast and sides are thickly 
marked with irregular brownish or dusky spots. In this plumage the Bluebird, 
appears very much like some of the thrushes from the spotted appearance of its 
breast. 
Habitat. — Eastern United States to the eastern base of the Rocky mountains, north 
to Manitoba, Ontario and Nova Scotia, south, in winter, from the Middle States to 
the Gulf States and Cuba. Bermudas, resident. 
This common and well-known species is found in Pennsylvania dur- 
ing- all months of the year, but in the height of the winter season they 
are much more plentiful in the southern counties than elsewhere in this 
region. In summer Bluebirds are abundant and generally distributed 
throughout the state. These birds, when not engaged in building, are 
usually seen in flocks of from ten to twenty each, sometimes, however, 
particularly in the fall, they collect together in large numbers, as will 
be seen from the following extract taken from one of my note books : 
“ October 23, 1884, Girard Manor, Schuylkill county, Penn’a. Bluebirds 
very abundant ; a flock of about two hundred have every day for the 
past two weeks been observed distributed over the field surrounding the 
residence of my friend and host M. M. MacMillan, Esq., busily engaged 
in feeding or dressing their plumage while they perch on the leafless 
branches of the numerous young trees scattered along the fences. When 
feeding the birds confine their operations to the ground and feed chiefly 
on grasshoppers, which are abundant. The fields about here appear to 
be favorite feeding resorts, as they come in large numbers in the morn- 
. ing, and remain, if not driven away, for about two hours. They also 
come in the afternoon, but not in such large numbers.” The Bluebird 
builds a scanty and loosely-constructed nest of dried grasses, feathers 
or other soft materials in holes of trees or stumps, in bird-boxes, or in 
hollo\7S of posts and fence rails. The eggs, usually four or five in num- 
ber, are light blue and unspotted. They measure about .81 long by .62 
wide. The eggs of this bird sometimes, though very rarely, are white. 
