Sometimes it just boils down to sheer luck. I am not very good at spying and/or identifying Warblers. Somewhere around sixty of them are listed in Sibley's Guide West, referring to the American western states. Of these, I've seen eight, but I only find one or two in any regular fashion, the
Orange-crowned Warbler, and the wonderfully named
Yellow-rumped Warbler, otherwise known as Yellow-butt. The Yellow-butts are so common that I get sort of impatient about identifying little yellow birds high above me in the oak canopy. I'll try and try to get a clear shot of these very active birds and finally find after craning my neck for thirty minutes that it's yet another Yellow-butt.
But yesterday something strange happened. The bird I was tracking turned out not to be a Yellow-rumped Warbler. The breast was bright yellow, it had a grayish-olive colored back, and it had a complete eye-ring. It took me a moment before I realized it was a Nashville Warbler (
Oreothlypis ruficapilla), only the second one I've ever seen. The pictures are not great, although the first shows the reddish color sometimes seen on the head of the males (I didn't even see that until the pics were loaded onto the computer). But these three pictures were the only usable ones out of the forty pictures that I took. This was a challenging individual.
As
I've noted before, this warbler clan shows the effect of isolation on the evolution. The western population of the Nashville Warbler is a brighter yellow than those found in the eastern United States, and it was once considered a separate species called the Calaveras Warbler, a name I find much more interesting. We can still call it by that name, since it is officially a subspecies called
Oreothlypis ruficapilla ridgwayi.
Oh, and by the way, the bird has little to do with Nashville. It breeds in Canada and the Pacific Northwest and migrates in winter to the tropics. The ones seen in Nashville that gave the species its name were simply migrants passing through.
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