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Species reported: Blue-headed Vireo (Vireo solitarius)

Date and time of record: Sept 23, 2005; ~1000am

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

Other observers: Graham Fairhurst (field assistant)

Date report prepared: Dec 14, 2005

Locality: Camas National Wildlife Refuge (NWR), Jefferson Co.

Habitat: riparian woodland oasis (surrounded by desert and agriculture) at about 4800’

Conditions: Mostly cloudy 45-65’; light to moderate winds. The bird was observed at a distance of between 30’ – 50’.

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 of the Rocky Mountains in Idaho and the only other of the Solitary complex we observed or captured (34 banded) at Camas during 2005. I noticed immediately that this bird appeared more ‘contrasty’ in its coloring than most Cassin’s – thus, I continued to observe it in seek of 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 brightest Blue-headed Vireo I have ever seen; thus, it may have been a hatch-year bird and/or a female but I wouldn’t be sure.

Behavior of bird: the bird was actively but deliberately foraging on the limbs of several Russian Olive trees. It moved relatively slowly and was sometimes hidden from view for up to a minute; however, I was able to follow its movements for over several minutes initially and then re-found the bird with Graham about 20 minutes later and he saw all the field marks and concurred with the ID.

How and when did you positively identify the bird, and what clinched the identification for you? As soon as I saw the bird, I thought it looked brighter than the Cassin’s I had been seing all fall and I soon had Blue-headed Vireo in mind. 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 Lucky Peak 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