Birding Notes

Reflections on birds and other wildlife on the edge of a southern woodland

Wednesday, October 10, 2007

Singing While He Preens – A Northern Mockingbird

When I think of a bird singing, usually I picture a feathered head lifted, bill parted, and throat quivering as the notes come out – a classic image. I’ve known that many birds can sing with their mouths full, or even with their bills closed, but I had never fully appreciated this until I watched a Northern Mockingbird running through his repertoire this morning while preening.

It was late morning, hot and sunny, but sitting on the front porch, I was in the shade and could feel a light northwest breeze. The parched grass and shrubs were thickly littered with small brown water oak leaves and acorns – making it at least look like fall, even if it didn’t feel like it. Except for Chickadees, Titmice and one female Red-bellied Woodpecker on the feeders, the yard was quiet until the Mockingbird began to sing.

For a while, I watched the Red-bellied Woodpecker feeding, admiring the silky-sheen of soft red on the back of her head, the small smudge of reddish-orange over the long, sharp bill, the mottled markings on the white underside of the tail, and the fine detail of white patterns on black wings and back.

Then she flew, and I turned my attention to the Mockingbird’s song and, feeling lazy, began to try to identify the different songs it incorporated . . . Blue jay, Bluebird, Carolina Wren, Titmouse, Chickadee, Phoebe, Cardinal, Red-bellied Woodpecker, Blue-gray Gnatcatcher, White-eyed Vireo? – I think so – Towhee, Goldfinch, Brown-headed Nuthatch . . .

The Mockingbird sat in a pecan tree, on a low-hanging branch that was mostly bare of leaves and in full view, and sang enthusiastically for fifteen or twenty minutes. For almost all of this time, it was also preening and scratching, and after a minute or two, I realized that it rarely seemed to open its bill at all, except to part it slightly now and then. The effect was disconcerting. As it poured out a steady, uninterrupted stream of songs, it preened its breast and wings, fanned its tail and raked its bill through the feathers, and scratched its head vigorously several times. This looked so remarkable that I briefly thought maybe there must be one bird I was watching and another that was singing. But there was no other Mockingbird around, and even when it did not seem to open its bill at all, I could see its throat and upper breast trembling with song.

For a minute or two, he fell silent, and sat still, head up alertly. Another Mockingbird was singing in the distance. Then he scratched his head, and began to sing again.

He showed a decided preference for Bluebird, Blue Jay, and Carolina Wren songs or calls and returned to them most often. He also seemed to like Phoebes – both their song and their fussing, burbling calls. More than once I heard the chik-brrr of a Scarlet Tanager, a Hairy Woodpecker’s kingfisher-like rattle, a Summer Tanager’s pik-a-tuk, the high, needle-thin calls of Titmice and Chickadees, and the perfect whreep of a Great Crested Flycatcher.

For a few minutes, he stopped preening and settled down just to sitting and singing, but even then he still did not seem to open his bill more than parting it slightly. Then he scratched his head, stretched out one wing, and began to preen again, still singing. The rich, full, musical sounds seemed to come from nowhere. Certainly it didn’t look as if they were coming from this bird so obviously preoccupied with its grooming.

In a brief search of books and web resources, the best explanation I found of this ability of some birds to sing without seeming to open their bills is in The Birdwatcher’s Companion to North American Bird Life, by Christopher W. Leahy (2004). Leahy explains that bird songs and calls are produced in an organ called the syrinx, which is analogous to the human voice box (larynx), but unique to birds. “Attached to the syrinx are pairs of muscles that control the quality of sound production. The songbirds have a maximum complement of syringeal muscles, up to 8 or 9 pairs.”

“It will be noticed,” Leahy continues, “that birdsong, unlike human speech, is not inflected much (if at all) by resonating in nasal, mouth, or throat cavities. This is dramatized by the ability of many species to sing full, rich songs with their mouths full or their bills closed.”


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