Photo courtesy Charles Martinez
This week’s Bird of the Week, compliments of the Weminuche Audubon Society and Audubon Rockies, is the warbling vireo.
Vireos that spend the summer in our area can be difficult to spot high in the treetops. These small songbirds don’t wear flashy colors, and their methodical searching for insects while hidden by foliage doesn’t call attention to their presence. What gives them away is their habit of singing nonstop, even at midday when other birds have gone quiet.
The warbling vireo that breeds here is a greenish-gray bird with a darker crown, whitish eyebrow and dark line through the eye. Like others in the vireo family, it has a stout bill with a tiny hook at the end. Although these birds can be difficult to see, hearing their distinctive cheery up and down songs will alert you to just how many of them are hiding in the trees.
In summer their breeding range extends across most of the United States and western Canada. They inhabit mature woodlands with deciduous trees and are rarely found in purely coniferous forests. Their winter range is compressed into a much smaller area of western Mexico and northern Central America.
Adult moths and butterflies and their pupae and caterpillars are the mainstay of the warbling vireo diet. They also eat other insects and spiders, adding some berries and fruits in fall and winter.
Males are highly territorial, declaring ownership and fending off rivals in song. During nest building and while the female is incubating eggs in the nest at night, he stays nearby and guards her. The nest is a hanging, rounded basket built by the female and suspended from the rim in the fork of a deciduous tree.
Both sexes share incubation duties and feeding of the young. Males are such songsters that they even sing while sitting on the nest. Follow the song now and you may be able to spot this elusive bird and its hidden nest.
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