25-B-2019 Chestnut-sided Warbler

STATUS
Accepted
DATE VOTING COMPLETED
1ST ROUND
7-0
HOW MANY OBSERVED?
1, immature plumage
DATE SIGHTING OCCURRED
DATE REPORT PREPARED
REPORTER
Carl Lundblad
OTHER OBSERVERS
Observed later the same day by Greg Lambeth and Neil Paprocki
LOCALITY OF OBSERVATION
University of Idaho Arboretum and Botanical Gardens, Moscow (Latah County)
HABITAT WHERE THE BIRD WAS OBSERVED
Heavily manicured arboretum with well-watered lawns and a diversity of native and non-native plantings. The bird was in an area of lilac shrubs, low hedgerows (ID unknown), some Russian Olives, Spruces, Lombardi Poplars, and other trees.
SIGHTING DURATION, CONDITIONS, and EQUIPMENT USED
<10 seconds in the morning under overcast skies, slightly breezy, with Bushnell Elite 10X42 binoculars. In the evening I again encountered the bird, when I hard it calling for up to 2 minutes and glimpsed it for 2-3 seconds.
DID YOU TAKE NOTES?
Yes, during the observation
DID YOU CONSULT A FIELD GUIDE OR OTHER REFERENCE WORK?
No, not at all
DESCRIPTION OF THE BIRD(s)
Description copied verbatim from notes entered into eBird immediately following initial morning sighting: "Small short-tailed warbler, bright lime green above from forecrown to rump, plain unmarked gray below including on face, white eyering, 2 pale yellowish wingbars."
BEHAVIOR OF THE BIRD(s)
In the morning, I found the bird foraging low (2-3 feet off the ground) in a hedgerow and adjacent Russian olive, associating with a flock that included 2-3 Wilson's Warblers, and American Redstart, Spotted Towhee, 2 Song Sparrows. Typical active warbler foraging behavior. It quickly disappeared. I believe it was silent during my morning encounter. I spent a lot of time trying unsuccessfully to relocate it. In the evening (starting around 6:15 PM) I returned and sent half an hour looking for it and was about to give up when I heard emphatic "smacky' junco-like warbler chips which I tracked to a small grove of ash trees. About as soon as I spotted the chestnut-sided if flew ~100 meters to a grove of small spruces, where it continued to call for another minute. I couldn't spot it, over there, but recorded it until it stopped calling, at which point I figure it went to bed shortly before 7PM.
HOW AND WHEN DID YOU POSITIVELY IDENTIFY THE BIRD, AND WHAT CLINCHED THE IDENTIFICATION FOR YOU?
The first second my binoculars landed on the bird, I had no doubt it was a Chestnut-sided. The bright yellow-green upperparts, gray underparts, eyering, lemon yellow wingbars, are absolutely distinctive. As soon as my binoculars hit the bird, I dropped them and reached for the camera....
HOW DID YOU ELIMINATE SIMILAR SPECIES? WHAT WERE THEY?
No other warblers (or other birds) look like this. Tennessee Warbler is not so distinctly bi-colored, lacks wing bars, and lacks an eyering. Nashville Warbler is yellow blow, not gray. Yellow Warbler is a chunkier bird with longer tail, is less distinctively/cleanly bi-colored, lacks strong wing bars, and has a weaker eyering.
WHAT IS YOUR EXPERIENCE WITH THIS (AND SIMILAR) SPECIES?
I have seen many Chestnut-sided Warblers in the tropics (especially Costa Rica), in the eastern U.S., plus vagrants in New Mexico (4+) Arizona (2+), Nevada (3+), and this is now my third in Idaho. I have probably seen a lot more in nonbreeding and immature plumage than I have alternate adults, so this is a very familiar and instantly-recognizable plumage.
DESCRIBE YOUR GENERAL BIRDING EXPERIENCE
~19 years of "serious" birding, mostly in the western U.S. and neotropics. eBird reviewer in 2 states. Current or former BRC member in 2 states. Final-year Ph.D. Candidate studying avian ecology.
ADDITIONAL INFORMATION (If any)
I got one godawful but recognizable photo (Bryce Robinson called it a, "diagnosable blob of colors"). Greg Lambeth obtained a considerably photo which I will try to provide to the committee, and see photos by Neil Paprocki on eBird: https://ebird.org/view/checklist/S59625725. I also recorded the bird's chip notes during the evening encounter and will provide that documentation, as well. My photo and audio are also included on the following eBird checklists:
https://ebird.org/view/checklist/S59610273
https://ebird.org/view/checklist/S59626794
WERE PHOTO(S), VIDEO, AND/OR AUDIO OBTAINED FROM THIS SIGHTING?
Photo
Audio
SUPPORTING IMAGES
SUPPORTING AUDIO

FIRST ROUND VOTING:

Cliff Weisse
Accept

Description supports identification of Chestnut-sided Warbler.

Shirley Sturts
Accept

Well documented

Dave Trochlell
Accept

I'm convinced.

Darren Clark
Accept

Description is good, photograph is not great, but helps.

Doug Ward
Accept

Excellent report noting most of the primary field marks of this distinctive plumage. The “godawful” photo showing a "diagnosable blob of colors" was actually just that, diagnosable!

Jay Carlisle
Accept

Well documented

Heidi Ware Carlisle
Accept

Perfect example of how even a 1 star photo can be valuable for documentation. Great recording too!