Rare Bird Report #: 85-B-06

Idaho Bird Records Committee Rarities Report Form

Species: Tennessee Warbler

Reporter: Jay Carlisle

6105 Kirkwood Rd

Boise, ID 83709

jaycarlisle@boisestate.edu

Other Observers: Frederic Van Hove, Zoltan Nemeth

Date Report Prepared: 12-11-06

Date Sighting Occurred:8-1-00 (capture)

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

Habitat: montane deciduous shrubland bordered by coniferous forest

Conditions: I do not remember

Did you take notes?not at all

Did you consult a field guide or other reference work? during the observation

What guide(s) or reference(s) did you consult?

Pyle’s 1997 ‘The Identification Guide to North American Birds’, National Geographic

Description: A small Vermivora warbler with a slender bill; a greenish back; a grayish head; a distinct, dark eye-line splitting a broken eye-ring; whitish underparts; and a relatively short tail (as compared to similar appearing Vermivora warblers like Orange-crowned).Wing: 64mm; Tail: 42mm.

Based on complete skull development and plumage, this bird was identified as an adult male.

Note: The bird was in worn plumage and therefore had not begun its annual, prebasic molt to replace body & flight feathers. The bird was also carrying zero fat.As this date is earlier than expected for the fall migration of this species (most records are late Aug to early Oct – with adults tending to migrate later in the season) and adults of this species normally complete their flight feather molt prior to beginning fall migration, in my mind this raises questions about where this bird summered (i.e. maybe nearby?).However, we had been banding daily for 2 weeks prior to capturing this bird and had yet not detected the bird – suggesting that it was not on territory at the banding site.

Behavior: none observed as this was a bird captured as part of a standardized bird migration study

How and when did you positively identify the bird, and what clinched the identification for you? Clinching features included the whitish undertail coverts, bright greenish back, gray head, and the dark eye-line. Additionally, the relatively short tail was another diagnostic field mark.

How did you eliminate similar species, and what were they? Orange-crowned Warbler (always has yellow undertail) and Warbling Vireo are 2 possible candidates, with the vireo being more similar to an adult Tennessee but Orange-crowned being more structurally similar. However, the combination of the features mentioned in the above section all help to separate from Orange-crowned and other Vermivora species. Additionally, Orange-crowned Warblers have a longer tail and an Orange-crowned Warbler with a 64mm wing (very large end of spectrum for Orange-crowned) is most likely to have a tail measuring over 50 mm (as opposed to 42mm).Warbling Vireo, which has similar (but not identical) coloration, is eliminated by the thin bill structure and greater contrast between head and back.

Experience with this species (and similar species): I have observed many hundreds, if not thousands, of each during migration and winter in both the US (especially South Dakota for Tennessee) and Mexico (Orange-crowned) and Central America (Tennessee).I have also captured and several immature and 1 adult female Tennessee during fall migration at Lucky Peak and Camas NWR along with well over 1000 individuals of Orange-crowned Warbler in Idaho.

General birding experience: extensive; 14+ years in US and Latin America

Were photo(s), video, and/or audio obtained by you? (If yes, please include or attach)Yes, but not by me.See 2 attached photos (scanned & a bit grainy) taken by Fred Vanhove. One picture shows the bird by itself (better clarity) and the other shows the bird (center) bracketed by a Nashville Warbler (right) and a Warbling Vireo for comparison.