This week’s Bird of the Week, compliments of the Weminuche Audubon Society and Audubon Rockies, is the plumbeous vireo.
The plumbeous vireo is a small songbird with a big voice. Birds in the vireo family are described as constant singers, especially in spring, when song is used to attract a mate and define nesting territory. They will even sing while sitting on the nest.
Despite broadcasting their presence with repeated singing, they are difficult to find in their typical location high in the canopy of a ponderosa pine. Here they forage deliberately while inspecting branches, bark crevices and needle clusters for the insects and spiders that they eat. Moths, butterflies, bugs, bees, wasps and beetles are all a part of their diet.
Plumbeous vireos have a relatively small breeding territory which includes most of Nevada and Utah, western portions of Colorado and New Mexico, and the higher elevations of eastern Arizona. Here they nest in dry, montane coniferous and mixed forests, particularly those of ponderosa pine, Douglas fir, aspen and Gambel oak up to around 8,200 feet elevation.
These vireos take their name from the Latin word for leaden, a reference to the rich gray color of their upperparts. They are white underneath and the bold white lines around their eyes that extend over the bill give them the appearance of wearing spectacles.
A short, thick bill is hooked at the end, an aid in holding onto squirming prey.
When it’s time to build a nest, plumbeous vireos move closer to the ground to attach the rim of their tightly woven cup from a forked tree branch. A perfectly constructed nest is formed using fine grasses, other plant fibers, bits of spider webs, string and animal hair.
Lichens and moss attached to the outside serve as camouflage.
Despite both parents sharing incubation duties, their nests are frequently parasitized by a cowbird female who sneaks in to deposit an egg. Both parents also share in raising the chicks. Once the young birds have left the nest, families may forage together for a while, but disband before leaving for Mexico by the end of September.
For information on events, visit www.weminucheaudubon.org and www.facebook.com/weminucheaudubon/.
Photo courtesy Charles Martinez