A Song for APRIL 16

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Click the sonogram to hear and see the sound.

When we lived outside Eugene, the Evening Grosbeaks came ever year like clockwork. They didn't stay to nest, as far as I know, but they were around for weeks, perhaps fattening up on the abundant ash seeds before going elsewhere to nest. It was a welcome incursion. I heard their flight calls often, but on this particular date I was startled to hear something else. The cut above starts with a breet and several loud peer flight calls are thrown in, but it is dominated by the insistent repetition of chirps, with an occasional chirp-breet. There are two examples of this behavior at the online companion to Pieplow's books and both seem to involve multiple birds, perhaps at close quarters, as mentioned by Pieplow on page 410. Probably I just happened upon a singleton performing a rarely-recorded display, but in retrospect it sounds like singing to me. Repeating one motif, in this case chirp, several times, then capping it off with another motif, in this case a modified breet, is a common syntactical structure in bird singing. I would be interested in learning of other examples of Evening Grosbeaks using this particular combination.

But there's more. In 2004, authors from UC Davis showed that Evening Grosbeak subspecies were distinguisable by their calls. The subspecies were described, as most subspecies have been, on the basis of minute or subtle differences in pigment saturation and body proportions, things that one could perceive in museum study collections decades ago. Many species have subspecies of this sort, and the variation in phenotype usually (but not always) does represent some reduction in gene flow between the various populations. The work in Tom Hahn's lab at Davis continued, and Ebird has taken up the cause, giving observers the option of choosing one of five call-types when listing this species. I did it for the cut above, and had to justify my choice of Type I. Of course, the recording helped with that. To help with the decision, they provide a detailed description of the five call-types, as well as the history of the range expansion and contraction of the species. It's a must-read.

The Evening Grosbeak has a special place in my bird-focused odyssey. I "had the gene," as they say; I was obsessed with birds from toddlerhood on. Fortunately, my father and uncle were birders, had binoculars and Petersons, and I got plenty of encouragement from them. It really took off in the fifth grade when I memorized all the plates in the Peterson field guide. There's nothing quite like the enthusiasm of a ten-year-old. So, when Evening Grosbeaks flew up from the sidewalk as I pedalled to school one cold morning, I knew what they were. I told my father. He compassionately informed me that I must be mistaken, because the species was not mentioned in South Carolina Birdlife, by Alexander Sprunt and Burnham Chamberlain. A few days later, after seeing them himself, he apologized. So I wrote Mr. Chamberlain a letter detailing my observations. He wrote back, saying that the birds had started showing up since his book had been published, and, by the way, I should join the Carolina Bird Club. I did, and all the rest is the story of my life. Never underestimate the impact an act of kindness can have on a fifth-grader. The change in abundance and distribution of the Evening Grosbeak that led to that pivotal observation is explained nicely in the article linked above.

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