Idaho Bird Records Committee Rarities Report Form

Species: Tennessee Warbler

Reporter:
Cliff Weisse
4125 Beaver Springs Rd.
Island Park, ID 83429
cliffandlisa@octobersetters.com

Other Observers: None

Date of Observation: 5/18/09

Date Report Prepared: 5/18/09

Locality of Observation: Camas NWR, in the row of trees running north from headquarters along Camas Creek, a.k.a. The dogleg

Habitat: Desert oasis

Conditions:  Sunny and calm, virtually no wind.  Sun was from the side and the bird was seen both in sun and in shadow at 8:45-8:50 AM.  distance ranged from 15-50 feet and not higher than 15 feet from the ground.  Bincos used were Nikon Premier 10x42.  Previous weather was high pressure for two days.  

Did you take notes… Yes, about two hours after observation.  

Did you consult a field guide or other reference work?  Yes, later the same day and after writing notes.

         Peterson's Warblers and Sibley Field Guide to Birds of North America.

Description: A slender, short tailed warbler with pointed thin black bill.  The bill was observed at close range and was not thick based and definitely not hooked.  I did not notice if the base was pale and did not try to determine if it was.  The crown and nape were dull grayish brown, darker than the rest of the contour plumage except for the thin, dark/blackish line through the eye, much more distinct than Orange-crowned Warbler (which I saw minutes before and after seeing this individual).  The supercilium was pale yellow.  The auriculars were dusky and the throat and upper breast were yellow, not as bright or intense as the yellow of a Yellow or Wilson's Warbler, but more like a heavy yellow wash.  The mantle was greenish yellow, lik eolive washed with yellow, as was the rump.  The underparts were whitish with a wash of yellow on the vent and rear flanks.  There was no streaking on the mantle, breast or flanks.  Undertail coverts were clean bright white.  The tail was short, square, and dark with some white in the outer rects (as seen from below).  It was not as dark above and I could not see white when the bird flew short distances despite looking for it, but the center of the under side of the folded tail when the bird was perched showed some white.  The wing coverts were similar in color to the mantle (maybe not quite as bright but I didn't specifically look at this) and the greater and median coverts were tipped pale forming two indistinct wing bars.  The bar on the median coverts was tapered and considerably shorter than the one on the greater coverts, which was of even width across the feather tract.  The wing bars were not strongly contrasting and definitely not white, but the color is hard to describe.  Maybe dull buff?  The primaries were darker than the wing coverts.

Behavior: Foraging in deciduous trees mostly by probing new leaf clusters, very similar to the typical foraging behavior of Orange-crowned Warbler.  this behavior allowed excellent views of the bird which was not moving around as much as expected for this species.  The bird vocalized at one point giving five or six high thin chip notes.  These chip notes were thin and not nearly as emphatic as Orange-crowned Warbler's chip note.  My impression is that the bird gave these chip notes when it became alarmed but I couldn't tell why it suddenly acted nervous because I was not moving at that point.

How and when did you positively identify the bird, and what clinched the identification for you?  I first saw the pattern on the face and breast, then the white undertail coverts and immediately though it was a Tennessee Warbler.  Further study revealed the pointed bill, indistinct wing bars, etc. which conclusively eliminated Philadelphia Vireo.

How did you eliminate similar species, and what were they?  Orange-crowned Warbler has bright yellow undertail coverts and a longer tail.  Philadelphia Vireo has a longer tail, thicker hooked bill, and lacks green mantle and wing bars.  I can't think of any other warblers that could cause confusion.  Arctic Warbler is a very remote possibility but it has extensively pale bill, not as much contrast between nape and mantle, gray or olive rather than bright geeenish mantle, more distinct wing bars, and distinct thin white eye arcs.

Experience with this species: I've seen only a few Tennessee Warblers and one Philadelphia Vireo.  I see dozens of Orange-crowned Warblers annually.

General experience birding: 17 years

Were photo(s), video, and/or audio obtained by you?  No