John Wingfield has seen one-third of the known bird species on this planet, from the black coucal of Kenya to newly hatched longspurs in Swedish Lapland.

But Wingfield's bread-and-butter bird is a brown, sedentary, nondescript creature with little going for it besides an ability to bench-press a song like none other. It can have more than a dozen songs, actually: varied, convoluted, contorted, sweet songs, like bebop flute.

It is the song sparrow, and one could make a good case that it is the quintessential Northwest bird, a humble homebody that likes wet feet and ranges from the coast to the mountains, Oregon to British Columbia.

With spring's arrival, the song sparrow has been in fine form, earnestly staking out territory and pitching woo, singing its intentions all the while.

"You'll see when they come close, they put their whole body into it," said Wingfield. "They put an incredible amount of effort in their songs."

Songs of the song sparrow The songs are all from M. m. morphna, the local song sparrow subspecies. The songs were recorded by Todd Sperry at the University of Washington's Charles Lathrop Pack Demonstration Forest, not too far from Mt. Rainier National Park. The different songs are simply variations of the same sparrow song type. Each bird has its individual song repertoire, which usually consists of between 5 and 13 song types. This repertoire is used to establish and defend territories as well as to attract mates. • Song #1 Real Audio file (17K) MP3 file(30K) • Song #2 Real Audio file (24K) MP3 file (32K) • Song #3 Real Audio file (17K) MP3 file (29K)

Wingfield and fellow University of Washington researchers have featured the bird in dozens of papers. They have explored how it acquires its song after it is hatched, a feat that puts the sparrow on a par with parrots as one of the few bird species without hard-wired vocal patterns.

They also have observed how the male sparrow's gonads grow in spring and, come fall, shrink to about one-200th of that size. The bird's vocal organs shrink as well, making its crystalline songs shorter, noisier and less controlled.

Making the bird so easy to study is its abundance. Song sparrows are around during the day, and they're everywhere that is cool and wet, which is most everywhere here. Wingfield says it is "as close to an aquatic species as you can get." It will even stick its head underwater for food.

So what might take years to study in a rare bird can be done with a song sparrow in weeks. And there's a lot to be learned from a little brown bird, particularly from its hormones, which Wingfield, an environmental endocrinologist, has plumbed to see the powerful role they play in both the expected and unexpected changes of a song sparrow's life.

Like almost every high-latitude plant and animal, the song sparrow changes as the days get longer. The bird knows to do this through extrasensory perception, or at least with something beyond the traditional five senses.

Several decades ago, a French researcher removed the eyes from ducks and found the animals were still sensitive to changing hours of daylight. The light, it turns out, goes through the skull and much of the brain to the hypothalamus, control center for the endocrine and nerve system.

Wingfield went further, but with a kinder method. He put opaque eye patches on his birds and noticed that having eyesight can actually hinder reproduction, the way city traffic distracts a horse without blinders. Later, he removed the eye patches and released the birds to resume life in the wild.

DID YOU KNOW... The song sparrow's testosterone levels, aggression rise when its social stability is threatened

Wingfield has also used song sparrows to examine the role of testosterone on aggression. In the early 1980s, he reviewed the scientific literature on testosterone and found that researchers were divided over whether such a link truly existed. Looking more closely, he noticed that testosterone levels and aggression seemed to rise when an animal's social stability was threatened.

He developed what he calls the "challenge hypothesis." On a recent walk around campus, he demonstrated this by broadcasting a repertoire of recorded song-sparrow calls through a small speaker set near the Montlake Fill. In an instant, a nearby song sparrow turned his head, then his whole body.

"See?" Wingfield said, "He's looking down."

The bird disappeared into some brush to the side, then returned and landed right by the speaker.

"He's doing the 'tsst, tsst' call," said Wingfield in the accent of his native Derbyshire, England. "That means he's pretty ticked."

The bird's wings dropped. His tail was propped up. He looked like a rooster spoiling to fight.

"It means he's aggressive," Wingfield said. "But he's frustrated because he can't see it."

Under more controlled circumstances, Wingfield has tested his hypothesis by challenging caged male song sparrows with a decoy and recordings of another song sparrow. Thus challenged, up went the male's testosterone.

Wingfield also put testosterone implants in birds and released them. Up went their aggression. That in turn upset the social stability of their neighbors. Up went their testosterone. In the right situation, like coming to the defense of your territory, so much testosterone can be a good thing. But it can carry a price.

"When you've got a lot of testosterone, you're liable to get obnoxious," Wingfield said. "You get picked off by predators. That's the ultimate cost. You get injured. Also, they get so aggressive they can drive females away. So there's a whole host of these costs."

And that cost is not carried by little brown birds alone. Humans pay a price for not only testosterone but other hormones such as estrogen and estradiol. How we turn off these hormones may be just as important as how we turn them on, Wingfield said.

The song sparrow, clarion Lothario of the soggy Northwest spring, might be able to tell us that.

Eric Sorensen can be reached at 206-464-8253 and esorensen@seattletimes.com.