A Song for July 11

With a white eye-ring and white outer tail feathers, the Vesper Sparrow is one of the easier streaked sparrows to identify by eye. It is also easy to identify by ear, as every song begins with one or more clean whistles, which may ascend slightly, descend slightly or hold steady on a single frequency. The whistles are followed by all manner of notes and phrases, most repeated several times. This whistle + jumble combination rings across the steppes and prairies of North America, at dawn and most notably at dusk, mostly north of the 40th parallel, but well south of that in the Sierras, Rockies, and Appalachians. And somewhat incongruously, it also may be heard in the Willamette Valley of Oregon.

I heard two whistles here and there on the south slope of Mt. Pisgah, identifying the bird with ease. Funny, then, what the sonogram reveals. The two whistles were NOT the signature intro whistle of a Vesper Sparrow. They were the second phrase in a multi-phrase song. The signature whistle appears once, at best, in each song, and is faint. It is followed by two loud whistles, each preceded by a puff of sound, as though the whistle were a whale's back and these puffs were its breath. Looking at the samples in the Macaulay Library, it is common for the first phrase to be a whistle with grace note, like the ones seen here, but it is not universal. It is therefore not uncommon to hear two unadorned whistles, followed by two with grace notes, followed by two broadband whistles, and only then hear a trill or two. But the Vesper Sparrow has many choices. Just focus on the first part of the song and you will always recognize it.

The south side of Mt. Pisgah is the south end of the Willamette Valley. The Willamette Valley, along with the Puget lowlands, and parts of the Unmpqua and Rogue Valleys, have been grasslands long enough to allow the local Vesper Sparrows to differentiate a little from the rest of the species. They are known as Pooecetes gramineus affinis. This bird was singing from the top of a tree, an oak, something I have never seen a Vesper Sparrow do anywhere else. But this brand of Vesper Sparrow is a savannah bird. It can tolerate, and exploit, a few trees. It will still nest on the ground, under a bush or a tuft of grass. But it does need that grass. The efforts to restore the wet prairies and to save certain endemic plant species from extinction should help this unique form of Vesper Sparrow survive as well. Once lost, unique local forms are not soon recreated. It's better to keep what you have.