CONWAY DAILY SUN COLUMN

COUNTRY ECOLOGY

© “RED-EYED VIREO”

  One of the most common birds of the Eastern forests, the inconspicuous red-eyed vireo, is heard far more than it is seen. It sings its endless series of short phrases continuously from the upper reaches of the forest canopy from dawn to dusk on the hottest of summer days, when other birds are becoming silent. The vireo's ventriloquist song is a series of phrases interspaced with short pauses, like the song of an American robin broken into pieces. This musical song is a broken series of slurred notes; we hear it all the time. Each phrase usually ends in either a downslur or an upswing, as if the bird is asking a question, then answering it, over and over.


  Even in warm midday without respite, the male red-eyed vireo continues this familiar, robin-like repetitive refrain high above our heads in the deciduous forest greenery. Sometimes this red-eyed vireo has been called the “Preacher Bird,” because he punctuates the end of each of his phrases with a slightly rising inflection as he supposedly chants, “You see it. You know it! Do you hear me? Do you believe?!”


  And, he is performing much of this in-between bites, because he is foraging for caterpillars all the while in the shady foliage, and I have seen that! Its horizontal posture and slow movement through the understory of broad-leaved woods make it an easy bird to study, if you can find him. The bird moves slowly for a large warbler, and then munches insect life as he consistently trills. He has even been observed singing with his mouth full, as he sluggishly moves along a tree’s branches in the bird’s breeding territory. I was lucky enough to sight one in some lower, leafy limbs.


  Though difficult to locate, we hear this alert bird all the time we are walking in the woods. (I know you would recognize its song if you heard a recording.) Their persistent song is legendary among songbirds. A single individual was once heard to sing 22,197 songs during a single day. It is continuous, in short individual phrases, as many as 40 to 60 per minute, and is frequently heard in forests throughout the summer breeding season. Perhaps it is celebrating the return of our widespread, contiguous forests that recaptured northern New England during this century, following the earlier colonial and Civil War eras.


  This is the common vireo throughout much of North America. The red-eyed vireo is about five inches long, and has a thick bill with a hooked upper mandible. There is a ruby-red eye, visible at close range, and a white eyebrow that is bordered above and below with black. Whitish underparts contrast with an olive back, which leads to a pale, blue-gray crown.


  These red-eyed vireos were once considered one of the three most abundant birds of the forests of Eastern North America. Now, populations of red-eyed vireos are said to be declining elsewhere. Unfortunately, the beautiful vireo nest is one of primary targets of cowbird parasitism. Female cowbirds find and lay their eggs in this species’ nest. The cowbird eggs hatch early and the young cowbirds out-compete the youngish vireos for food and space with the result that these nestlings perish. Their recently declining numbers might possibly also be a result of the destruction of wintering habitat in the neotropics, or fragmentation of northern forests, among other causes.


  In the understory, the female red-eyed vireo builds her curious nest that is beautiful, dainty, and basket-like. Suspended in a horizontally forked branch, in a slender sapling, it is found about 10-15 feet off the forest floor. Commonly discovered by foresters and surveying crews, the intricate, well-built, thin-walled nest is “always built the same way” by their reports, of grasses, paper birch strips, grape vine tendrils, and rootlets. The delicate weaving of the birch’s bark throughout is one of the best field marks for identifying the red-eyed vireo’s nest. Craftily bound by supporting spider web, it is also decorated with lichens on the outside to hide it. I have a collected one suspended from the wall near my wood stove’s chimney—it seems fitting there!


  These birds are obviously very important for maintaining the health of our forests. This vireo is a neotropical migrant that makes its way from its home in Central and South America to our deciduous woodlands of North America to select a territory, win a mate and raise 3-4 young--on sometimes just an acre. They consume large quantities of insects and caterpillars harmful to tree foliage. It is an effective predator on gypsy moths, fall webworms, tree hoppers, scale insects and others. This is a deliberate stalker in the forest undergrowth and green canopy overhead; no insect prey escapes unnoticed. On their wintering grounds, however, they are said to switch over to fruits.

 

  Dave Eastman also broadcasts “Country Ecology” four times weekly over WMWV 93.5 fm.  As Vice President of the Lakes Region Chapter/ASNH, he welcomes you to monthly programs at the Loon Center in Moultonborough.  He is available at:    for consultation.

 

 

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