IDAHO RARE BIRD REPORT FORM

 

Species reported:  Blackburnian Warbler (Dendroica fusca)

 

Date and time of record: Sept 2, 2008

 

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

 

Other observers: Heriberto Verdugo-Munguia, Kris Ohlenkamp, Marissa Buschow (all seasonal field assistants at IBO)

 

Date report prepared: Oct 27, 2008

 

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

 

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

 

Conditions: Sunny with cool temperatures; light winds.  The bird was captured and banded – thus seen very close.  We had the bird in hand for about 15 minutes before release.

 

Did you takes notes? No.

 

Did you consult a field guide or other reference work? If so, which guide(s)? During observation: National Geographic and the Peterson Guide to Warblers

 

Description of bird: Clearly a small Dendroica warbler based on wing bars, facial pattern, tail spots, etc.  The bird was about 5”, had a wing chord of 62mm and tail length of 45mm, and the bird weighed 8.9 grams.  The bird had a primarily brown back with indistinct streaks in the mantle feathers and distinct whitish wing bars; distinct supercilium and malar stripe bordering a brownish auricular patch with irregular edges at the posterior; the breast was dominated with yellowy-orange and this color washed into the light facial areas – including the supercilium – as well as the flanks; lower underparts (i.e. below chest) were largely whitish to buffy with some streaks on upper flanks/sides of chest; and the bird possessed a distinct central crown stripe.  Our determination was that this bird was a hatch-year (immature – based on incomplete skull ossification & plumage) and probably female based on the shorter wing and the patterning on back and uppertail feathers.

 

Behavior of bird: only observed in the hand.

 

How and when did you positively identify the bird, and what clinched the identification for you? I pulled the bird from its cloth holding bag and I knew right away it was not a Townsend’s. Clinching ID features included the brownish tones in the back with pale stripes and the orange-yellow tones on the face and chest.

 

List similar species and how you eliminated them: similar species include many Dendroica warblers; but only Cerulean (D. cerulea), Townsend’s, and Black-throated Green (D. virens) are likely to cause any confusion.  Cerulean is considered the closest relative to Blackburnian but is separated by bluish or greenish toned upperparts, muted yellow underparts on females and immatures, indistinct back of auricular, and a lack of distinct streaking except on adult males.  Townsend’s are characterized by being greener above and yellow below as well as having more extensive black streaking in all sexes.  Townsend’s also has a neater outline of the auricular patch.  Most Townsend’s also tend to be more distinctly streaked on the back.  Black-throated Green Warbler is less likely to be confused because their facial pattern is less distinct & they share the green back with Townsend’s – among other dissimilar features.  Immature females are most likely to be confused; however, their auricular is much less distinct, they have yellow and green as opposed to orange and brown, and their wing bars (coverts) are more extensively marked with black.

 

What is your experience with this or similar species?  I have captured good numbers of Blackburnians and Ceruleans (as well as all eastern Dendroica) during spring migration in Louisiana.  I have also observed these species during spring, summer, and fall in SD, LA, CT, and other eastern states – including many immature Blackburnians.  Townsend’s are among the most common warblers observed and captured at the site in Idaho and I am very familiar with all age/sex classes of this species.

 

Describe your general birding experience: I have been birding for many years. This birding has occurred in the US and in many Latin American countries.  I have extensive experience with most North American warblers in all plumages and on breeding and wintering grounds and during migration.

 

Were photos, video, and/or audio obtained? Yes, see attached.  Also, if appropriate, please also see the 9-3-08 post on IBO’s blog: http://idahobirdobservatory.blogspot.com/2008/09/blackburnian-warbler-9-2-08.html  in which I show a Townsend’s for comparison.

Photos are resized and one is cropped from originals.  No other editing was done.