Sep 18 2008
Just about every birder has heard the phrase, “confusing fall warblers.” It’s fallen out of fashion with the birding cognoscenti, who maintain that it’s inaccurate–fall warblers, in their view, are not confusing and saying they are just discourages people. Indeed, the new Peterson guide replaces “confusing,” with “selected.” I’m not entirely sure it’s an improvement, though there would have been a lot of moaning and wailing if they hadn’t.
While I take the points about not making an intimidating mountain of a manageable molehill, I confess a lingering fondness for the old “CFW.” I agree it can be overdone; moreover, I agree that most fall warblers are pretty straightforward. But even pretty savvy birders still encounter fall warblers that do–there’s no better way to put this–confuse them. I suppose you could substitute words like “confound,” “mystify,” or “bewilder,” but those sound pretty antiquated.
My friend Sharon observed and photographed a warbler yesterday morning near her house in Rehoboth Beach, Delaware. She circulated some of the photos to a few birding friends and received a number of suggested identifications, all of which I thought were reasonable, but most of which were incorrect. So I asked her permission to do a quick post walking through the process by which I arrived at my diagnosis. Of course, I could be wrong and I encourage you to challenge anything I say in the comments. Here’s photo #1:
You can click on the photos for a larger view, which will probably help.
OK, ready? Let’s go through one possible process for identifying this bird.
1. Warbler looks like a good call–the bill is too thin and not hooked enough for a vireo.
2. Right away, we can slash our list of possibilities down to just a few frontrunners, based on the whitish wingbars, dark face pattern, yellowish wash underneath, and blurry streaking at the sides of the breast. Note also that there is a partial collar of brighter color wrapping up the sides of the neck, behind the auriculars, as well as rather bold white eye crescents. Let’s look at a few candidates and see if we can rule them out.
3. Orange-crowned Warbler wouldn’t show obvious wingbars; bill is too big & heavy.
4. Cape May Warbler has a very fine black bill, often looking somewhat decurved. This bird’s bill is dark but not black and looks paler near the base. It’s also pretty heavy, not at all fine or needlelike.
5. Blackpoll Warbler usually shows straw colored legs–it also has a very different shape. Look at photo #4. Our mystery bird has quite a long tail and rather short wings, exactly the reverse of the ultra-long-distance migrant Blackpoll. This shape also is a deal breaker for Cape May. Face pattern looks awfully dark and blurry and eye crescents too big for Blackpoll.
6. Bay-breasted Warbler is a bit chunkier than Blackpoll, but still can’t match our bird’s long-tailed, short-winged shape. It is also unstreaked underneath and more brightly colored overall.
7. There are certainly other candidates that might be put forward; e.g., Prairie or even Yellow-rumped, but I think most birders would quickly eliminate those (insert vice-presidential joke here). If anyone wants to suggest any write-ins, use the comments and I’ll address them.
8. What this bird does seem to match in every respect is Pine Warbler, at least a hatch-year one (one born this summer). Pine Warbler is a bird for which a lot of us seem to have a less-than-fully-formed mental image. It’s kind of dull, but quite variable. It often sticks to the treetops and unless you live in a place (like I do) where it’s a yard bird, you just may not see it very often.
But Pine is a chunky warbler, with a fairly heavy bill, a long tail, and blurry streaking and a dark face setting off a clearer throat and breast. It also has prominent but not blazing wing bars, and whitish (or yellow) eye crescents. It also has a bit of a neck patch, one reason a lot people might consider Cape May as an option for this bird.
If you click on photo #3, you might discern the undertail pattern, which shows narrow dark outer webs (towards the sides of the tail) and extensive white inners (towards the center of the tail) that extend all the way to tail tip, looks perfect for Pine. In Blackpoll & Bay-breasted, the dark tail corners are more extensive, nearly or entirely cutting off the white before it reaches the tail tip.
In the end, it’s probably photo #4 that is most helpful in clinching this identification, even though it shows less color and detail than the others–it’s just such a long-tailed, chunky, heavy-billed warbler. I should also add that #4 wasn’t in the series that Sharon initially circulated.
I hope this analysis is useful to some of you. Again, if you want to take issue with or ask questions about any points I’ve raised, please do so. And if you’d like to test yourself with some more fall warbler fun, check out this post from Bill of the Birds.
Thanks to Sharon Lynn and her friends for a neat learning opportunity.