Philadelphia Vireo

September 15, 2017

Philadelphia Vireo
Vireo philadelphicus
 
by Paul Cianfaglione
Early to mid September is the best time to find Philadelphia Vireo in Connecticut. It is a widespread northern breeder, occurring in most of Canada, northern New England, and the Adirondacks, but its migration period is brief. The entire population retires to Central America for our northern winter.
 
Where to find it: The Philadelphia Vireo breeds in young second-growth deciduous woodlands and in fall migration it will also favor younger second-growth trees, especially those bordered by water. Another excellent place to look is along powerline rights of way. Search for Philadelphia Vireo among mixed flocks of other birds, including chickadees and Red-eyed Vireos, foraging within the middle strata of the forest edge.

Andy Rzeznikiewicz of Connecticut Audubon saw three at the organization’s Trail Wood Sanctuary in Hampton on Wednesday and one near the Center at Pomfret on Tuesday. Stragglers may be passing through as late as Columbus Day.
 
What it looks like: Because of its similarity with the more common Warbling Vireo, the Philadelphia Vireo is sometimes overlooked during its brief fall appearance. Overall, Philadelphia Vireo is slightly smaller, more rotund looking, stubbier-billed, and shorter-tailed than Warbling Vireo.

Its plumage is grayish above with a contrasting darker crown. Philadelphia also shows a dark eye-line which extends to the base of its bill. Warbling lacks this eye-line, creating a blank-faced expression.

It is also important to note the distribution of yellow on the underparts. With Philadelphia Vireos, the yellowish colors are most intense on the center of the lower throat and upper breast area. The Warbling Vireo’s distribution of yellow on the underparts is greatest along the flanks and undertail coverts.

Another species that may cause identification problems with the Philadelphia Vireo is the Tennessee Warbler. Many Tennessee Warblers, especially in fall, share similar plumage patterns. However, Tennessee features a very thin, sharp-tipped bill, slimmer body and bright white undertail coverts.
 
Conservation status: The IUCN considers the status of Philadelphia Vireo to be of Least Concern. Many kinds of human activities that set back succession may benefit this species on breeding grounds, including clear-cutting, selective logging, and burning (Laughlin and Kibbe 1985). (Source; Birds of North America Online Edition).

Photo by Dominic Sherony/Carolinabirds.org