Bird of the Month: Warbling Vireo
By Hugh Jennings
Scientific Name: Vireo gilvus
Length 5.5 in
AOU Band code WAVI
The Warbling Vireo (WAVI) is about 5.5” long. Its genus Vireo is from Latin meaning ‘a kind of bird.’ The species name is also Latin for ‘pale yellow’. It is the grayest and palest of our vireos with no wing bars, with the only head marking being an indistinct stripe over the eyes. It has a whitish breast which sometimes has a yellowish wash.
The WAVI nests throughout the U.S. It arrives in our state in April or May and heads back south about September. It occurs throughout the state in deciduous and mixed deciduous-coniferous woodlands at low to moderate elevations. In Western Washington it favors alders and big-leafed maples. The birds are hard to see as they forage among the yellow-green, but their song is very distinctive. F. Schuyler Matthews’ “Field Book of Birds & Their Music” describes it as follows: “A smooth, continuous flow of about nine or more notes of equal value. The sound does not resemble a song as much as it does a bit of fantasia, caprice, or the somewhat rapid movement of a sonata. When the bird begins he runs on until he has finished, without break, pause, or any unevenness whatever.” A famous ornithologist, T. Gilbert Pearson, likened it to the sentence “If I could see it, I would seize it, and would squeeze it, till it squirts.”
Its diet is mostly insects during the breeding season. It is more likely to eat berries and small fruits in late summer and fall. In the west its nest is often placed in a shrub or tree within 30 feet of the ground. The west, built by both sexes, is a compact, deep cup, suspended by its rim from a forked twig. The nest is made of bark strips, grass, leaves, and plant fibers. Usually 4, sometimes 3-5, eggs are laid, white with brown or black specks. Both parents incubate the eggs for 12-14 days. The male frequently sings from the nest while incubating. Sadly, the nests are commonly parasitized by cowbirds. The young are fed and brooded by both parents and leave the nest 12-16 days after hatching.