Home & Garden Columns

Wild Neighbors: Meet the Pacific Wren (and Other Brand New Birds)

By Joe Eaton
Tuesday August 03, 2010 - 07:31:00 PM

A tip of the hat to John Westlake for alerting me to the recent publication of the 51st Supplement to the American Ornithologists’ Union checklist, essential reading for any active or recovering birder. As happens every year, the AOU has voted to accept or reject a number of proposed changes in bird nomenclature for the Western Hemisphere and Hawai’i. This includes the recognition of new species (splits), the demotion of old ones (lumps), taxonomic reshufflings at various levels, and changes in common and Latin names, sometimes just to correct the gender of the Latin. The process is an incidental boon to publishers, who can justify new editions of Peterson, Sibley, National Geographic and the other standard field guides. 

The splits and lumps are the main focus of attention. This is when birders learn that their life lists have increased overnight, even if they haven’t been out in the field for months. Or, conversely, shrunk, although that doesn’t happen much these days. The splitters seem to be firmly in the saddle. This year’s supplement includes four species-level splits for North American and Hawai’ian birds, and no lumps at all. 

The full text of the supplement is only available at this point to subscribers to The Auk, but a birder named Michael L. Retter has posted the gist of the changes on his website

So what’s new? The black scoter, a sea duck that winters along the California coast, is now recognized as a distinct species from the common scoter of Eurasia; it retains its old name. I believe the British birding authorities adopted this change some year back. 

I don’t know if the common scoter has ever shown up here. 

The whip-poor-will has been split into two species: the broadly ranging eastern whip-poor-will and the Mexican whip-poor-will, which reaches the mountains of southeastern Arizona. These are both cryptic nocturnal birds, far more often heard than seen. Fortunately their voices are distinctive: the eastern says “Whip-poor-will,” while the Mexican’s call is described in one guide as “a burry pwurr-p’wium,” lower and slower than the eastern’s. Either would be unlikely in California. 

Not as unlikely, though, as the newly recognized species of ‘elepaio, Old World flycatchers endemic to the Hawai’ian islands. 

The Hawai’i (Big Island), Kaua’i, and Oahu subspecies have been promoted to full species status. Plumages differ from island to island, but range is sufficient to identify a species; these sedentary birds don’t make interisland flights. If you see an ‘elepaio on Kaua’i (which takes a bit of work these days), you can bank on it being a Kaua’i ‘elepaio. I will admit to having been skunked by the Oahu form a few years ago. Since the three forms never have the opportunity to interbreed, how do we know they’re valid species? Good question. Maybe the genetics were persuasive. 

The big deal for most mainland birders will be the wren decision, another three-way deal: winter wren (the old name for the species) in Eastern North America, Pacific wren in the West, and Eurasian—the unmodified wren of British birdlore—in Europe and Asia. I don’t know where the geographic boundary has been drawn between winter and Pacific. According to Sibley, plumage differences between the two forms are subtle. But the songs of the males are distinctive, and female preferences for the “right” song type keep the species reproductively separated even where the two forms nest side by side. 

Other species-level changes were proposed, but rejected as unjustified or premature. These included splitting our own western scrub-jay into coastal and interior species, dividing the curve-billed thrasher into western (Arizona) and eastern (Texas) species, and separating the South Hills crossbill, a bird endemic to a single mountain range in Idaho, from the widespread red crossbill. Apparently there are votes, a little like the process the astronomers went through in downgrading Pluto. More than likely there’s lobbying, armtwisting, backroom deals. 

I’m not sure why the jay and thrasher proposals failed, but I think I understand the decision on the crossbill. Most likely the AOU just didn’t want to go there. Once you start messing with the crossbills, you’ve opened Pandora’s box. The “red crossbill” may actually be a complex of at least nine species, best distinguished by flight call and mostly nomadic, so you can’t sort them out by range. The chronic uncertainty would really bother a lot of birders. 

At higher taxonomic levels, the longspurs and snow buntings were moved from the sparrow family to their own family; the wrentit, an anomalous California bird which was formerly in a family of its own and then placed with the babblers, is now considered an Old World warbler; and the osprey is now the sole member of a new family. Typical hawks (like the redtail and Cooper’s) and eagles were placed in a separate order from the falcons. Herons, ibises, and spoonbills were transferred to the pelican order, which lost the gannets, frigatebirds, cormorants, anhingas, and tropicbirds to two new orders. 

That’s this year. Give it time and maybe new tools for genetic analysis, and it’s all subject to change. Some of us are still waiting for the terrible revenge of the lumpers.