A birder who I have been watching gradually develop into one of the most talented observers I've ever met recently sent me some photos of empids, i.e. flycatchers of the genus Empidonax. Some of them I could do something with, some I could not. Here is a paraphrase of the advice I emailed back on one of the photos (not the one above; that one is of a Yellow-bellied Flycatcher at Higbee Beach WMA, NJ a few years ago):
"Apparently absent eyering, moderate to longish primary projection past tertials suggest Alder/Willow. Apparent paler gray color suggests Willow. Timing leans towards Willow (Alders in fall begin slightly later and are much more predominate later in the season than Willow).
"I am not sure. The Bird Banding Lab does not allow/accept i.d.'s to species for Willow versus Alder in the hand, by the way.
"Here's the thing. Nobody should fool around trying to sight I.D. Empidonax flycatchers unless and until they have studied many known identity birds (i.e. singing or calling) of all the species reasonably possible at their location at length. And then you have to watch out for pewees, which I've seen pretty much everyone, including me, call empids, and not always self-correct.
"I've looked at a lot of empids, and have found that my perceptions of field marks on the same bird can change substantially as it changes position or the light changes. Eyerings appear and disappear. Primary projection past the tertials becomes longer and shorter. Grayness becomes greenness becomes brownness all on the same birds. But the songs tell all, and in fall, the calls do too once you learn them and are patient enough to wait for one to call. A lot of times I'm not patient, and they go down as Empid sp., because I figure in the time it takes to hear a call note or finally figure out the field marks confidently, I can find 8 species of warblers and some cuckoos. . .
"Of the field guides, Sibley is the best for Empids, but it would also be worth looking at Kaufman's Advanced Birding."
There you have it.
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