Northern Prairie Wildlife Research Center
Vireos belong to the family Vireonidae, which is derived from the Latin word vireo, meaning "a kind of bird". This family of small songbirds are all 4-7 inches long and plain olive green or gray above and white to yellow below. The sexes are similar with no seasonal plumage change. Twelve species breed in North America but most winter in the tropics. Members of this family which can be seen in North Dakota include the yellow-throated vireo, Bell's vireo, Solitary vireo, and warbling vireo.
The warbling vireo can be found throughout North Dakota during the spring and summer months. It is the grayest and most pale of the vireos, lacking wing bars and characteristic eye-ring. This bird inhabits woodlands, isolated trees in open country, hedges, and city parks. The male will often sing hour after hour on a conspicuous perch. Vireos are mostly insect eaters taking flies, beetles, ants, aphids, and grasshoppers.
A pair of vireos will build a typical cup-shaped nest in the fork of a slender branch that is 30-60 feet above the ground. The nest is made of grasses woven together and held in place by spider's silk. The female lays 3-5 eggs and incubation is shared between the female and the male.