Fri-D: Blackpoll Warbler

[Blackpoll Warbler, Cape May NJ, October 14, 2016. Click to enlarge photos.]

Today, Friday October 14, 2016, it was a blackpoll morning in Cape May, a tad late in the season for thousands of these amazing long-distance migrants to still be passing through, but there they were. Yellow-rumped Warblers out-numbered Blackpolls, but certainly won't outdistance these long-distance migrants, some of which fly from Alaska to the Canadian Maritimes, then over the ocean to South America in a flight that takes as long as 88 hours non-stop!

Blackpolls are the classic greenish-yellow wing-barred confusing fall warbler things that trouble more than one good birder. The photo above is a tad more difficult than even the usual fall warbler, because I took it during the low-angle sunlight of dawn. This means the bird looks slightly yellower than it is.

One favorite approach to bird i.d. is to ask, "Why isn't it a . . .?" With Blackpoll, the why isn'ts are Bay-Breasted and Pine Warblers, both of which are less common where I live than Blackpoll. There are other why isn'ts, like Blackburnian or Cerulean, but they're easier to sort out.

So why isn't it a Pine Warbler? The obvious back streaks are a good go-to here, though structure helps if you are familiar with both birds. Blackpolls are slimmer than Pines and have finer bills and much longer wings, manifested by primary feather tips sticking way out past the tertial feathers.

Why isn't it a Bay-breasted? This is the toughest similar species to Blackpoll, plus everybody wants it to be a Bay-breasted since they're scarcer. The warm light in this photo temps one to call Bay-breasted, because the flanks look slightly yellow or even bay. But: the undertail coverts are contrasting bright white, the wing bars are too narrow, it has obvious streaking below, it lacks a contrasting light collar on the nape, and if you don't like those reasons, it has yellow feet (Bay-breasted has dark feet.)

 Above, Blackpoll in morning flight. Contrasting yellow in front/white behind below, zeep flight call (annoyingly shared by several other warblers), and, a fine point, FAST, as you would expect from a long-distance migrant. If you're lucky enough to be in the middle of a warbler morning flight, and a bird starts passing everybody, think about Blackpoll.