Winter wren: little bird, big song

It looks far too tiny to produce such a song, a liquid glissando that rings through the woods.

The winter wren is a little brown bird with a very big song. It's a demitasse of a bird, weighing less than half an ounce. But it can bench press a tune like no other local songster, with a voice 10 times more powerful, ounce for ounce, than a crowing rooster.

And its song comes when we need it most. While other songbirds of the Puget lowlands ditch us to head to warmer climes for the winter months, the winter wren, true to its name, lives here year-round. And sings.

It's no easy feat: The wren puts its whole body into the effort, breast heaving and tail trembling as arpeggios of notes pour out of its open beak.

It tips its head back, the better to let the music fly, and breathes circularly, like a woodwind musician, producing continuous song for eight seconds and more. The birds have two voice boxes, the better to sing with.

But why sing at all? To establish and defend territory, for one. And to attract — and keep — mates, for another.

Only the males sing. But it's the females that actually shape the birds' repertoire, by choosing the mates whose music they find most pleasing, said Donald E. Kroodsma, professor emeritus of biology at the University of Massachusetts Amherst, an expert on bird song.

"We can assume they sing really long and complex songs because the females demand it," Kroodsma said.

If so, the lady wrens in these parts are sophisticates, urging their partners to ever more virtuosic heights of performance. Winter wrens in the West sing more than twice as many notes per second (36) as their counterparts in the eastern United States (16).

Kroodsma learned that the songs consist of highly organized and repeatable sequences of different notes.

While two males on the East Coast he studied sang only two song types, one wren he studied intensively in Oregon sang at least 30.

"A male requires several hours and perhaps a couple of days to present even his more commonly used song types," Kroodsma noted. And each song may consist of more than 300 notes.

All the more impressive given that winter wrens aren't born with their songs. They have to learn them.

By August, the woods are full of the arias of adult and young wrens, practicing away.

"You listen to the adults sing and they are sharp and crisp and clear," Kroodsma said. "And when you listen to the young ones, you can tell they are muddling through; they really have to learn; it takes an enormous amount of practice."

By the end of their first year, most winter wrens have mastered a very stable repertoire of songs they will sing for life. The music is a songprint of the bird's neighborhood, with pieces of music learned from the adults around them. (And not usually their fathers, by the way, whom they ignore.)

"They sing in dialects; you can tell where the bird has been, and which songs he's learned," Kroodsma said.

Birds don't hear song the same way we do; they hear tones we do not, and an intricacy to the song that eludes human ears, Kroodsma said.

Yet these are not fussy, $100-a-ticket artists, they are the people's performers: flexible, adaptable and abundant birds, happy in a tangle of blackberries, sword fern and even the remnants of forest left in Seattle neighborhoods.

"That's a lot of bravado!" said Adam Sedgley of Seattle Audubon as a winter wren kept right on singing, center stage atop a sunlit branch, even as the No. 33 Metro bus ground up a nearby hill, and a noisy troupe of school kids romped along a trail on a recent morning at Discovery Park.

No performance anxiety here. Helicopters flew overhead. Dogs barked. A garbage truck banged away at the visitor's center. A train rumbled through Interbay. Didn't matter.

The wren swept his glinting gaze back and forth across his small kingdom and just kept singing and singing, tiny claws clinging to his branch, breast pumping with the effort.

"He has a lot to prove, apparently," said Sedgley.

"That's one boisterous bird."

Lynda V. Mapes: 206-464-2736 or lmapes@seattletimes.com