White-crowned Sparrow is often said to be the most abundant wintering bird in Arizona–and in many years it’s easy to believe, with hundreds and thousands out on the desert roadsides.
I’ve seen remarkably few of the species these past couple of weeks, but among them have been several dark-lored individuals probably of the subspecies oriantha. The “Mountain White-crown” is the breeding race of the southern Rocky Mountains, wintering almost without exception to our south in western Mexico.
This one was photographed on the cold morning of January 14 in the Sulphur Springs Valley. It shows nicely the rather severe badger-like head pattern, the dusky pink bill, and the cold gray flanks that so nicely eliminate boreal gambeli (our abundant wintering race) and the yellow-billed, brown-flanked coastal birds. But there’s a fly in the emberizid ointment.
Eastern birds of the nominate race are extremely similar to oriantha–so similar, in fact, that many taxonomists “lump” the two as leucophrys. But study of mitochondrial DNA from black-lored birds has shown that certain populations are more closely related to the coastal birds–and others more closely to pale-lored gambeli. Clearly this is a species (these are species?) in need of revision. Meanwhile, all we can do in the desert southwest is sort through them and admire.