My North Carolina aunt called the Red-eyed Vireo
the "Preacher Bird." She interpreted the vireo as singing in preacher-like
phrases: You-see-it, You-know-it, Do you hear me? Do you believe it?
researcher discovered that the Red-eyed Vireo sang its abrupt phrases 22,197 times in one
10-hour summer day.
After a diligent search for the source of the song, the bird watcher may be rewarded
with the sight of an olive-green, five-inch bird, with a white breast, gray cap, and
distinct, black-bordered, white line over its eye. The ruby-red eye is only visible if one
is very close. For the first year of its life, a vireos eye is brown.
The Red-eyed Vireo, like other members of its family, tends to stay on perch and
slowly, systematically search the surrounding foliage for insects, particularly tiny
caterpillars. So well does the birds green plumage blend with the surrounding leaves
that one may have been looking at him without knowing it until he moves.
The Red-eyed Vireo belongs to a small, distinctly New World family of birds, most of
which are indigenous to the American tropics. All vireos are small, greenish in hue, and
have a slight hook at the end of the bill.
A unique quality of the vireo family is that they all build basket-shaped, pendant
nests suspended between two forks of a sapling. The intricately woven nest of the Red-eyed
Vireo is 21/2 inches deep and is constructed of fine grasses, rootlets, strips of
grapevine bark, and paper from wasps nests cleverly bound together with webbing from
tent caterpillars and with spiders silk.
These nests are rarely seen when in use, for they are cleverly camouflaged among a
trees foliage. When trees lose their leaves in autumn, they become apparent and one
wonders how it was missed during summer.
Many years ago, I found a nest hanging from a dogwood tree in a public park in which
large pieces of facial tissue were woven. When it rained, the tissue became sodden and the
eggs fell through the bottom of the nest. So much for a vireo taking advantage of modern
The Red-eyed Vireo nests in all parts of the United States except the arid Southwest.
On arriving on breeding grounds in late April or early May, the vireo has made a long,
hazardous and nocturnal flight through Central America and Mexico from its wintering
territory in the area drained by the Amazon River in South America.
The Red-eyed Vireo often incubates an egg that has been laid in its nest by the
parasitic Brown-headed Cowbird. The cowbird egg hatches into a very hungry and demanding
nestling. The larger, more aggressive young cowbird demands and receives the insects
brought to the nest by vireo adults, whose own young are starving.
Initially, the Brown-headed Cowbird associated with herds of buffalo that roamed
through the grasslands of the prairie states. It was a symbiotic relationship: cowbirds
relieved bison of ticks and fed on the insects flushed from prairie grasses by the
movements of these big mammals.
A bird following herds of buffalo has no time for nest-building, incubation and feeding
of young. The cowbirds sought out and found the cleverly hidden ground nests of prairie
birds, where they laid their eggs and left the raising of young to host species.
As European settlers moved west and cleared forests for their crops, cowbirds moved
east to occupy new areas of open fields. They laid their eggs in the nests of smaller
species such as the Red-eyed Vireo.
Three hundred years is not a long time for evolutionary changes in behavior that enable
vireos to cope with a new predator. Eastern birds have not evolved strategies to enable
them to avoid incubating the cowbird egg and raising the demanding young. Some species
have been known to bury the foreign egg in the lining of the nest, add a new lining, and
lay another clutch of eggs. Others, such as the catbird, throw the speckled egg from the
As recently as 1966, ornithologist Chandler Robbins, author of Birds of North
America, declared the Red-eyed Vireo "the most abundant bird in eastern deciduous
forests." This is no longer true. Increased cowbird predation, fragmentation of
woodlands and possibly most decisive the loss of winter habitat in the
tropics, have taken a toll on vireo populations.
Many survive these depredations and reward a visit to mature woodlands with understory
trees such as dogwood and viburnum in which the little green birds hang their pendant
nests. The forest visitor has only to pause and listen for the voice of the woods, the
incessant yet affirmative monologue of a male Red-eyed Vireo as he asks himself questions
and quickly answers them.