_Vireo swainsoni_, BAIRD, Birds N. Am. 1858, 336 (Pacific coast).—
ELLIOT, Illust. Birds N. A. I, vii. _Vireosylvia swainsoni_,
BAIRD, Rev. Am. B. 343. _Vireosylvia gilva_, var. _swainsoni_,
COOPER, Orn. Cal. 1, 1870, 116. _Vireo bartramii_, SWAINSON, F. B.
A. II, 1831, 235 (in part; spec. from Columbia River?).
[Line drawing: _Vireo swainsoni._
12891]
(No. 5,321 ♂.) Similar to _V. gilva_, but smaller; colors paler. Bill
more depressed. Upper mandible almost black. Second quill much shorter
than sixth. Total length, 4.75; wing, 2.71; tail, 2.35; difference
between tenth quill and longest, .58; exposed portion of first
primary, .58, of second, 1.82, of longest (measured from exposed base
of first primary), 2.10; length of bill from forehead, .56, from
nostril, .29, along gape, .65; depth of bill, .13; tarsus, .70; middle
toe and claw, .56; hind toe and claw, .43.
HAB. United States, from Rocky Mountains to Pacific coast.
In the present bird the bill is darker in color, much smaller, and
more depressed, the depth at the base being less than the width,
instead of being equal to it as in var. _gilvus_. The wing is more
rounded, the second quill much shorter than the sixth, generally
shorter or but little longer than the seventh. In var. _gilvus_, the
second quill is about equal to the sixth. The second quill is about
.30 of an inch (or more) shorter than the longest in _swainsoni_,
while in _gilvus_ it is only about .20 shorter. The feet of
_swainsoni_ are weaker, and the colors generally paler and grayer. The
iris, according to Coues, is dark brown.
Young birds in autumnal plumage have the crown decidedly ash, the
sides more greenish; the wing-coverts pass terminally into a light
brownish tint, producing an inconspicuous band.
HABITS. This Western representative of the Warbling Vireo is found
throughout the western portions of our Union, from the Great Plains to
the Pacific, and from Arizona to the extreme northern boundary of
Washington Territory.
Dr. Cooper characterizes this as a lively and familiar songster. It
arrives, he states, at San Diego about April 10, and reaches Puget
Sound toward the middle of May, occupying nearly all the intermediate
country throughout the summer. It frequents the deciduous trees along
the borders of streams and prairies, coming into gardens and orchards
with familiar confidence, wherever cultivation has reclaimed the
wilderness. Like its Eastern prototype, its cheerful and varied song
is heard all day long until quite late in the autumn. They too build
their nests in the shade-trees of the parks of busy cities, singing
ever their delightful strains, unconscious of the busy and noisy crowd
that throngs the neighboring streets.
Dr. Cooper states that its nests are pendent from the forks of a
branch high above the ground, sometimes to the height of a hundred
feet.
Mr. Ridgway, who observed the habits of this species in Utah and
Nevada, speaks of it as the characteristic Vireo of the West. It was
found by him in all the fertile localities, and was one of the most
common birds in the wooded regions. He found it very generally
distributed through the summer, inhabiting the copses along the
streams of the mountain cañons, and the open groves of the parks, as
well as the cottonwoods and willows of the river valleys. In the fall
the berries of a species of the cornel that grows along the mountain
streams constitute its principal food. Its notes and manners are
identical with those of the Eastern species.
The nests of this species are not distinguishable, except in the
necessarily varying materials, from those of the Eastern birds. In
position, size, and shape they are the same. The eggs, four or five in
number, are white, spotted with brown and reddish-brown, and measure
.78 by .58 of an inch. The spots are somewhat darker than those of the
_V. gilvus_, and the shape more of an oblong-oval, in all that I have
seen. But this difference may disappear in the examination of a larger
number.
A nest found by Mr. Ridgway near Fort Churchill, Nevada, June 24, was
suspended from the extremity of a twig of a sapling of the cottonwood,
in a copse of the same growing in a river-bottom. It has a height of
two and a half inches, and a diameter of three. It is composed
externally of an elaborate interweaving of spiders’-webs, willow and
cottonwood down, and strong cord-like strips of fine inner bark. These
are strongly bound around the twigs from which the nest is suspended.
It is one of the most elaborately interwoven, homogeneous, and
well-felted nests of this bird I have ever met with. Another nest,
from Parley’s Park, Utah, obtained June 28, differs in having the
external portion woven almost exclusively of fine strips of bleached
bark, and is lined with fine wiry grasses. In each of these the eggs
were four in number, all oblong-oval in shape, but much more pointed
at one end in the latter nest.
This species was found breeding in Napa Valley, Cal., by Mr. A. J.
Grayson, and at Fort Tejon by Mr. Xantus.