BLUE YELLOW-BACK WARBLER. 
159 
on small winged insects. Low swampy thickets are its 
favourite places of resort. It is not numerous, and its 
notes are undeserving the name of song. It remains 
with us all summer ; but its nest has hitherto escaped 
me. It leaves us late in September. Some of them 
probably winter in Georgia, having myself shot several 
late in February, on the borders of the Savannah river. 
Length of the yellow red-poll, five inches ; extent, 
eight ; line over the eye, and whole lower parts, rich 
yellow ; breast, streaked with dull red ; upper part 
of the head, reddish chestnut, which it loses in winter; 
back, yellow olive, streaked with dusky ; rump, and 
tail-coverts, greenish yellow ; wings, deep blackish 
brown, exteriorly edged with olive ; tail, slightly forked, 
and of the same colour as the wings. 
The female wants the red cap ; and the yellow of 
the lower parts is less brilliant ; the streaks of red on 
the breast are also fewer and less distinct. 
127. $YLVIA PUSILLA, WILSON. — S. AMERICANA , LATHAM. 
BLUE YELLOW-BACK WARBLER. 
WILSON, PLATE -XXXVIII. FIG. III. 
The habits of this bird partake something of the 
titmouse ; but the form of its bill is decisively that of 
the sylvia genus. It is remarkable for frequenting the 
tops of the tallest trees, where it feeds on the small 
winged insects and caterpillars that infest the young 
leaves and blossoms. It has a few feeble chirruping 
notes, scarcely loud enough to be heard at the foot of 
the tree. It visits Pennsylvania from the south, early 
in May; is very abundant in the woods of Kentucky; 
and is also found in the northern parts of the State of 
New York. Its nest I have never yet met with. 
This little species is four inches and a half long, and 
six inches and a half in breadth ; the front, and between 
the bill and eyes, is black ; the upper part of the head 
and neck, a line Prussian blue ; upper part of the back, 
brownish yellow r ; lower, and rump, pale blue ; wings 
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