This beautiful warbler was flitting about along the pond at Davidsonville Park this morning. The olive-green/yellowish head and back immediately indicated warbler, but of course the question is, which warbler? Time to look for clues. This bird has very distinctive white eyerings, an almost neon yellowish/green head cap, and a clean whitish/grey neck, chest and belly.
Ah, here’s another good view. Two very distinctive white/yellowish wingbars. Boy, the eyerings really stand out. And the yellowish-green seems to extend down the back. What other pose do we have?
This photo taken as the warbler was flitting from branch to branch isn’t great, but it definitely shows the lime-green extending down the back.
So, let’s figure out the name of this warbler. I’ll start with the bold, double wingbars. Many warblers have double-wingbars, but several of them have yellow breasts, so we can eliminate the Yellow, Prairie, Magnolia, Northern Parula, Blackburnian and Pine Warblers. Other warblers with double-wingbars have whitish breasts, but they are streaked on or along their breasts, so that eliminates the Palm, Yellow-Rumped, Cape May and Blackpoll Warblers.
We’re down to just a few possibilities: an immature Pine Warbler, a Bay-Breasted Warbler, a Chestnut-Sided Warbler or possibly a Ruby-Crowned Kinglet. Let’s eliminate some more. The immature Pine Warbler has a supercillium (eyebrows), a faint eyering, and a much grayer back. The Bay-Breasted Warbler has white wingbars rather than the yellowish wingbars and faint eye-arcs-eyeline rather than clear, distinctive eyerings. Let’s check the Ruby-Crowned Kinglet. The Kinglet has a gray back and head rather than the yellowish-green/lime green cap and back, and it’s smaller and just shaped differently (plumper and almost neckless in appearance). So basically, we’ve eliminated all but one species: the Chestnut-Sided Warbler.
Now, let’s get into ‘The Warbler Guide’ to confirm our detective work. ‘The Warbler Guide’ identifies the following diagnostic characteristics: the striking white eyering, the plain gray face with the lime-green ‘cap’, the lime-green upperparts and cap. Check, check, check.
There we have it. This morning’s warbler is a Chestnut-Sided Warbler – a lifer for me!