Warblers with yellow extending far back on the face include Townsend's, Hermit, Black-throated Green, Golden-cheeked, and Cape May Warblers. The streaking on the back in many Setophaga warblers (including all five birds above) is often quite dark in adult male birds. This streaking is relatively light, so I'd lean towards a first winter male bird or a adult female bird. All of these species other than Hermit have evident streaking on the flanks in most plumages. These four also all have backs ranging from olive to bright green to solid black (Golden-cheeked). The light gray-olive back and olive crown really suggests Hermit Warbler. And that's what it is.
Here is the same bird, from a more identifiable angle. This bird has no black at all on the throat which concerns me about calling it an adult female. It's clearly not a typical adult male. The upper wing-bar (caused by white-tipped/mostly white median coverts) lacks distinct black centers as far as I can tell (may be washed out or covered by the other median coverts), which suggests this is not a first-winter bird. The brightness of the face is also evidence of an adult bird. Still, the face seems to be more typical of an adult male than female. The crown is olive with only a little black mottling, so adult male seems unlikely, but the very large black centers to the uppertail coverts suggest male! I would lean adult female on this, but I can honestly say I really don't know. I have only seen one other Hermit Warbler than this, and it had black on the throat, so I can't say for sure if this is really that atypical, but it is certainly an interesting comparison to any field guide. Any other ideas on age/sex? Townsend's x Hermit Warbler is a rather common hybrid, but I see nothing intermediate here that suggests that.
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I think that it is an adult female based on the the dark shading on the side of the face, the streaked back, and the dark feathers on the cap. The only characteristic not playing in my favor is that the throat has no dark coloring on it at all.
ReplyDeleteHey Tim, to me, although I haven't seen enough of these to say for sure, and think you are probably right, this bird still looks somewhat in between. The face is actually very bright, lacking any olive tones at all. I'm seeing some photographs of birds labeled as females with faces this bright, but december birds should have a major olive wash (Pyle 1997). You are right that the olive crown with some dark mottling and the lightly streaked back look female, but the face, and uppertail coverts look male (although the latter may be difficult to judge). The slightly darker yellow auricular seems consistent with adult male from some photos I've looked at, and not as much with winter female faces (still just judging from photos). An exceptionally bright adult female is not out of the question though. As you've already mentioned, though, the lack of any black plumage on the throat is puzzling. Still, I suspect that you are right, and this bird just shows some variation.
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