He sings Dad's songs; she sings Mom's.

Like some mammalian musicians, stripe-backed wrens pass down song repertoires within families. Among these tropical wrens, the brothers sing like their father, as distinct from unrelated neighborhood guys, while the sisters sound just like Mom.

These calls are somewhat like human name systems that give clues to paternal and maternal lines of descent, says J. Jordan Price of the University of North Carolina at Chapel Hill. His wren study is the first to document his-and-hers vocal traditions within a family, he adds, but as researchers trace song styles in more tropical bird species, the system may turn out not to be unique.

In many birds of the temperate zones, a young male picks up songs from his new neighbors when he leaves home and establishes a territory, Price says. Among these species, most females don't sing. Females of tropical species are likely to sing, but research on song origins there has lagged behind work on temperate species.

Price's investigation of song patterns grew out of a long-running study that had already documented the genealogy of stripe-backed wrens on a cattle ranch in the llanos, or seasonally flooded savanna, of northern Venezuela. The birds breed cooperatively in groups of up to 14, with adult offspring helping to raise later years' broods. Only the principal female of a group lays eggs, but the whole gang pitches in to build the nest, defend the boundaries, and collect insects for the hungry babies.

One of the males eventually inherits the territory from his father, and most of the brothers in the line of descent stay in the territory, as if waiting for a chance to take over. "It's like the British royal family," Price says.

The sisters are more likely to leave, rushing to a neighboring territory when its reigning female dies or disappears. Claw-to-claw combat determines which female becomes the new top bird. The losers go home to mother and wait for the next vacancy.

Price admits that the calls of these wrens are "not pretty." The main breeding male and female in a territory sing a duet that he calls a "harsh, raspy thing." For the vocal traditions study, he analyzed another call--twisty sounds nicknamed WAYs because they reminded early observers of a distorted human voice whining, "Where are you?" One of their functions, Price speculates, is to help birds keep in touch in dense foliage.

Price taped a total of about 10,000 of these WAY calls from 46 principal males, 22 male helpers, and 14 females. The calls clearly descended along family lines, passed from male to male and female to female, Price reports in the March 22 Proceedings of the Royal Society of London B. In two cases, he found nearly identical calls in males whose territories lay about a kilometer apart and then discovered that they had shared a great-grandfather 15 years ago.

"I'd be very surprised if the songs weren't learned," Price says. He bases his idea on the complexity of the wren's repertoire. Studies of birds raised in laboratories with different song environments have demonstrated that other species with complicated songs learn their repertoires.

Price's research seems "an important first step" to Rachel Levin of Pomona College in Claremont, Calif. What's needed now, she says, is more analyses of tropical birds.

Levin studies song in the bay wren, another tropical species whose males and females sing duets. "I'm working with extremely precise `whopdiddly whopdiddly whopdiddly [calls], where one sex is whopping and the other is diddlying," she explains. Such two-sex song patterns pose complex questions about learning and about how males and females end up with the right parts of the song.