Congratulations to all the contestants in last Friday's Fall Warbler ID Quiz. Alan Pulley, who blogs at this location, was the first reader to correctly name this mystery bird as a Tennessee warbler. Nice detective work, Alan!
My silence over the weekend was not due to my disapproval of the various guesses on the mystery bird's ID. Rather, I was blissfully out of touch with the Web while performing at The Berkeley Spring (WV) Fall Birding Festival. While there I got to see some old birding pals, make some new ones, and had the amazing experience of seeing nearly 1,000 migrant blue jays streaming overhead in groups of 6 to 40 during our Sunday morning bird walk at Sleepy Creek Retreat. No life birds, but a life birding experience seeing so many blue jays in the space of a couple of hours. The hurricane rains did nothing to dampen our spirits.
Now back to our mystery bird.
I did not use an image that showed the bird's face and head. Seeing the faint crowned appearance, the pale supercilium (line over the eye), and the very thin bill would have been really easy clues to the bird's identity.
The best initial step to take when trying to identify a drab fall warbler is to ask yourself: "Does it have wingbars?" If it does, you've already narrowed your potential species options to those WITH wingbars.
Next, check to see if the underparts are streaked. This narrows your choices even further.
(For a great synopsis of this process, get yourself a copy of Identify Yourself: The 50 Most Common Birding Identification Challenges. Eirik A.T. Blom, Julie Zickefoose, and I each wrote chapters covering the warblers in ways that we find helpful and memorable. Bird ID experts Jeffrey A. Gordon, Marshall Iliff, and George Armistead also share their knowledge in the book, which was published by Houghton Mifflin in 2005).
So what DID my mystery warbler photo show? It showed a bird with a uniformly greenish back and rump, with no obvious wingbars or tail spots. It appears to be only slightly lighter-colored below, with no obvious streaking on the underparts.
This eliminates chestnut-sided warbler which would appear paler/grayish-white below and which would show obvious wingbars. Pine warbler would show obvious wingbars, too and would be streaky below. A Cape May warbler would have a duller-gray back, but a lime-green rump. This bird's back and rump are the same color.
Orange-crowned warbler is an excellent guess. This is another Vermivora warbler, like the Tennessee. Both have finely-tipped bills; both are varying degrees of drab yellowish-green; and both lack obvious wingbars. (Please note the the orange crown on this species is not a field mark and is extremely hard to see.)
There are a few other clues that help to steer the identity of this bird to Tennessee warbler rather than to orange-crowned. The lack of streaking on the underparts, the lack of a yellow undertail (not well displayed in my photograph, sorry), and the location where the bird was seen: southeastern Ohio. Orange-crowned warblers are fairly unusual in the East in the fall, whereas Tennessee warblers are a very common fall migrant. (Tennessee warblers are rare in the West.)
Having grown up as a bird watcher in the East and Midwest, I am much more familiar with the Tennessee warbler than I am with the orange-crowned warbler. Every fall I see dozens and dozens of TNs on my farm. In 16 years there, I've seen exactly one orange-crowned.
Here is a fall Tennessee warbler bathing in our Bird Spa. Note the supercilium, the finely tipped bill, and the greenish back.
Sorry for the headless bird ID quiz photo. In the next one, I promise to show the head and face.