Hard Taxa

Young birder Mia Hartley is curious about something on p. 37 of the March/April 2013 Birding:

The rosy-finch to which she’s calling our attention is labeled, without any justification or explanation, a Brown-capped Rosy-Finch. Let’s take a closer look at the photo, by none other than Bill Schmoker:

 

Hmm… That bird looks distinctively gray-crowned. Why isn’t this a Gray-crowned Rosy-Finch?

In a nutshell, this is a fresh Brown-capped Rosy-Finch in fall. The bird has recently completed its single annual molt, and, as I understand the it, will gradually acquire a brown-capped plumage aspect in the months to come. By summer, when birders are looking for Brown-capped Rosy-FInches on their breeding grounds in the snowfields of the southern Rockies, the birds will look the way they’re “supposed to.”

The adult males are the (relatively) easy ones. Check that: The nonhybrid adult males are the (relatively) easy ones. I see apparent immature female rosy-finches in early winter that I cannot begin to put a name to. When I see big winter flocks in Colorado, I see adult males that seem to match well enough with one of the four distinctive populations (Hepburn’s, Gray-crowned, Brown-capped, Black) occurring in the southern Rockies, but, I swear, I see adults that look perfectly intermediate between, say, Black and Brown-capped.

And then there are the flight calls. I think—I kinda, sorta think—I’ve figured out some average differences: a muffled choof for Gray-crowned, a somewhat more ringing choor for Brown-capped, and a harder chop for Black. But I’m not sure of any of that. Where’s Nathan Pieplow when you need him?…

The bottom line is clear: Rosy-finches are hard.

But you wouldn’t necessarily glean that truth from your field guide. In my copy here of the 5th edition of Nat Geo, the Yellow-legged Gull—not exactly an everyday sighting in the ABA Area—receives more verbiage than all the rosy-finches combined.

 

When birders think of challengings IDs, certain taxa leap to mind: Calidris sandpipers, Empidonax flycatchers, “confusing fall warblers,” sparrows, jaegers, accipiters, scaups, dowitchers, and, of course, the notorious “LWHGs”—the large white-headed gulls of which the Yellow-legged is one.

Fine. Those are hard taxa. But what about other taxa that, for whatever reason, pose underappreciated ID challenges? I’ve already named one: the rosy-finches in the genus Leucosticte. Unquestionably, any given rosy-finch in winter in Colorado is going to be harder to ID, on average, than any given gull in winter in Colorado. But think about how much more has been written about winter gull ID than winter rosy-finch ID.

Okay, we’ve got:

1. Rosy-finches.

Let’s try to come come up with some others:

2. Catharus thrushes in western North America.

3. The “Solitary Vireo” complex.

4. The “croven” complex, the ABA Area’s five species in the genus Corvus.

5. Female orioles.

These are taxa that I regularly encounter here in Colorado. Note that each one involves at least three species, er, “species.” These give me fits. I frequently find myself incapable of making an ID, and I wonder how often I make the wrong ID.

 

As we work together to enumerate the underappreciated hard taxa of North America, let’s abide by a trio of ground rules:

First, and to make it fun, let’s restrict this to groupings with at least three so-called species. Thus, we’re disqualifying such pairings as Winter and Pacific wrens.

Second, let’s focus on ID problems that are routinely encountered by, hmm, “normal” birders in the ABA Area. Thus, crows and orioles, not Phylloscopus warblers.

Third, and this is really the biggie, we’re interested in hard taxa that fly under the radar. Yes, we all know that Parasitic Jaegers and Dusky Flycatchers are hard. But how about the birds that are just as hard, yet nowhere near as notorious?—Blue-headed Vireo & Co., Hermit Thrush & Co., Brown-capped Rosy-Finch & Co., and so forth.

What do you think?