A small gray-olive
bird with white underparts sometimes slightly washed yellow, the
Warbling Vireo is far less conspicuous to the eye than to the ear.
Since this bird is common, its song is part of our image of the
spring and early summer-woods. It is best detected by its long
flowing, warbling song which it sings throughout the day.
As in all vireos, the nostrils and part of the forehead are partly
covered with bristlelike feathers; the bill is slightly hooked at
tip with small notch.
Summer range of the Warbling Vireo is most of the United States,
except the south eastern states and Alaska, and western Canada. The
winter range is western Mexico and northern Central America.
Medium sized stocky vireo with a relatively short bill, rounded head
and subtle plumage. 14 cm long. 12g weight.
Upperparts primarily grayish-tinged olive green (except crown) and
underparts whitish, often with pale yellowish tinge, especially on
flanks and under tail-coverts. Face with moderately distinct white
supercilium contrasting indistinctly with grayish eye-line, but
otherwise very plain, without additional contrasting markings.
Remaining plumage also plain, lacking distinct wing-bars or other
contrasting markings or colours.
Sexes are alike and plumages similar throughout the year.
Duller than adults overall, averaging more brownish, with very pale
cinnamon or buffy wing-bars.
Warbling Vireo most is most frequently confused with Philadelphia
Vireo, which occurs widely in eastern North America and Middle
America. Both species are similar is size and general appearance.
Other, larger, eye-lined vireos that might be confused with Warbling
include Red-eyed Vireo which is larger and longer-billed and
relatively shorter-tailed with distinct dark border above and below
pale supercilium, creating a stronger facial pattern. The upperparts
are olive greenish (not grayish).
This is an inconspicuous bird. Gleans prey from tree foliage by both
searching through and hovering above it.
Eats insects and some berries.
A tree-top bird, the male sings hour after hour, filling days with
charming simple melody, matching summer calm of country from spring
through hottest days of July and August.
Unlike the abrupt, broken, short phrases of other vireos, song is
long, flowing warble.
Throughout its range, this Vireo shows a strong association with
mature mixed deciduous woodlands especially along streams, ponds,
marshes, and lakes but sometimes in upland areas away from water.
Also found in young deciduous stands that emerge after a clear-cut.
Found at edges or openings (both natural and human-made) as well as
forest interiors. Elevations of breeding habitats range from sea
level to 3,200 meters.
Other habitats include urban parks and gardens, orchards, farm
fencerows, deciduous patches in coniferous forests, mixed hardwood
forests, and, rarely, pure coniferous forests.
its broad breeding distribution, this species occupies a variety of
deciduous forest habitats and mixed coniferous, deciduous forest
habitats, which are predominately riparian. It builds its nests in
the forked limbs of trees from 1 to 40 meters above the ground at
elevations ranging from sea level to over 3,000 meters. The species
appears well adapted to human landscapes, as nests have been found
in neighborhoods, urban parks, and orchards. The nest is a typical
vireo suspended cup, woven around a forked branch. 3-5 dull white,
heavily spotted eggs. As with all vireos, both parents share
next-building and caring for the young.
for Warbling Vireo vary with geography. In California, for example,
they have been declining steadily for the past 20 years, while long
term trends in Ontario indicate that some populations are
increasing. Commonly parasitized by the Brown-headed Cowbird.
Capture rates (2010-2012; standardized as birds captured per
100 net hours) of Warbling Vireo indicate presence in the
park from May through September, peaking in August and
September as juveniles disperse. No captures from October to
April reflect this migrant's movement to Mexico and Central
America during the winter months.