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There are at least a dozen species of sparrows that spend all or part of the year in southern Arizona. They don’t all occupy the same habitat — some, for example, are grasslands species, others are desert dwellers — but all of them may be found within an hour’s drive or so of our Tucson home.
Some are easy to identify because they display distinctive plumage and/or also because they are uniquely identified with very specific habitats. For example, the Black-throated Sparrow, a little desert dweller, is unmistakable.
But, others aren’t so easy to identify. That’s often because their appearance is relatively nondescript and also because they share habitats with other species of sparrows, sometimes multiple other species.
That’s the case with today’s bird. I believe that this is a Vesper Sparrow.
I photographed it in the grasslands of Sonoita recently. That’s the perfect habitat for Vesper Sparrows — these birds are birds of open country, preferring to forage in grassy fields. Vesper Sparrows are a common species whose range includes the entire United States. They are seasonal (fall/winter) residents of southern Arizona. The identifying field marks on this bird include a complete white eye ring and a uniformly streaked back.
But, here’s where I hesitate a bit. This second bird, which I photographed only minutes before I photographed the Vesper Sparrow, is a Savannah Sparrow.
Like the Vesper Sparrow, it is a bird of open country. Its range overlaps all of the Vesper Sparrow’s range and it winters in southern Arizona even as does the Vesper Sparrow. The field guides describe its appearance as being similar to that of the Vesper Sparrow — an understatement, in my opinion.
There are subtle differences in appearance. The Savannah Sparrow has a fair amount of yellow plumage on its face, plumage that the Vesper Sparrow lacks. So, relying on that distinction, I’ll contend that the images I’ve posted today are of two different species, Vesper and Savannah Sparrow.
That said, I’m not 100 percent confident in my conclusion. There are often plumage variations within species. There probably are Savannah Sparrows that lack significant yellow plumage on their faces and their might be Vesper Sparrows whose plumage comes very close to that of Savannah Sparrows. So, I’ll make my identifications with a caveat.
I should add that I love photographing sparrows, partly because of the fact that species are so similar in appearance. There’s nothing like a good puzzle to keep my juices flowing, even if can’t always solve it with confidence.
Images made with a Canon 5Div, 400mm f4 DO II lens+1.4x telextender, M setting (auto ISO). First image, ISO 160, f5.6 @ 1/800, second image, ISO 250, f5.6 @ 1/1250.
What about what looks to me like a distinctive white brow streak on the Savannah sparrow, altogether missing on the Vesper (at least in these photos)? Would that also be a reliable distinguishing feature?