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Species reported: Blue-headed Vireo (Vireo solitarius)

Date and time of record: Sept 13, 2005; ~930am

Reporter: Jay Carlisle, Idaho Bird Observatory, Boise State University, 1910 University Ave., Boise, ID 83725; jaycarlisle@boisestate.edu

Other observers: none, other field assistants were too busy banding at the time

Date report prepared: Dec 14, 2005

Locality: Lucky Peak (Boise Foothills), Ada Co.

Habitat: mixed Douglas fir forest and mountain deciduous shrub at 5900’

Conditions: Partly with mild temperatures (45-52’); light winds. The bird was observed at a distance of between 20’ – 60’.

Did you takes notes? No.

Did you consult a field guide or other reference work? If so, which guide(s)? Immediately after observation: National Geographic and Sibley

Description of bird: Clearly a vireo of the Solitary Vireo complex based on the bold spectacle-shaped eye rings, wing bars, and color pattern. Cassin’s Vireo is the common spectacled, wing-barred vireo at this site. I noticed immediately that this bird appeared more ‘contrasty’ in its coloring than most Cassin’s – thus, I observed it for over 5 minutes, seeking and getting additional and closer views. The important characters that I saw on this bird included a primarily blueish-gray head contrasting with a bright green back, a very contrasting white throat, and relatively bright yellow sides. The bird was not the most contrasty Blue-headed Vireo I have ever seen; thus, it may have been a hatch-year bird and/or a female.

Behavior of bird: the bird was actively but deliberately foraging on the limbs of a Douglas Fir tree. Since it moved relatively slowly, I was able to follow its movements for over 5 minutes in the same and an adjacent tree.

How and when did you positively identify the bird, and what clinched the identification for you? As soon as I saw the bird, I had Blue-headed Vireo in mind due to the color contrasts (after seeing Cassin’s on a nearly daily basis all fall). However, I continued watching in order to confirm the ID features. Clinching ID features included the bright and contrasting colors: blueish-gray head, green back, bright yellow flanks, and white throat.

List similar species and how you eliminated them: similar species include the other 2 vireos in the Solitary Vireo complex: Cassin’s (V. cassinii) and Plumbeous (V. plumbeus). Plumbeous is a largely gray and whitish bird, lacking the yellow and green of the other species, and was therefore quickly eliminated. Cassin’s, however, is much more similar to Blue-headed, and requires more care in separation. Confusing the ID is that both species are characterized by a gradient between dull immature females and brighter adult males and the brightest Cassin’s adult males can approach duller immature Blue-headed Vireos. However, even the brightest adult Cassin’s do not show the gleaming throat or the distinct contrast between the greenish back and blueish head. Cassin’s show more of a continuous gradient between a green back and gray head.

What is your experience with this or similar species? I have captured and banded 50 -100 Cassin’s Vireos per year at the same site and have banded 4 Blue-headed since 2000 at the same site. I have also observed at least 50 - 100 of Plumbeous and hundreds of Blue-headeds during all times of year, especially in SD, ID, AZ, and Mexico.

Were photos, video, and/or audio obtained? No