Birds
Wren Duets
Rufous-and-white wrens use duets to find each other—and ward off intruders.
By Alisa Opar

Rufous-and-white wrens’ duets can be so closely matched that people often mistake them for solos.

Dale Morris, © Dan Mennill

When birds sing duets it can mean war. Or simply that the mates are trying to find each other in dense vegetation. For the first time biologists have shown that rufous-and-white wrens’ matched melodies serve these dual functions—a mystery that eluded researchers for decades, largely because Costa Rica’s thick forests make it difficult to observe the bird’s behavior. Dan Mennill, a biologist at Ontario’s University of Windsor, got around this obstacle by triangulating the birds’ positions with microphones. He found that the small brown birds locate each other with song—from as far as a football field apart—much as children do playing Marco Polo: One calls out, the other answers, and the first bird moves toward the second, repeating their song until they meet.

Mennill’s team triangulated the wrens’ positions in Costa Rica’s dense tropical forests by strategically placing eight microphones that recorded to a single laptop computer.

Dale Morris, © Dan Mennill

To see if wrens also use melodies to ward off rivals, Mennill played recordings of another pair, eliciting “an aggressive duet showdown.” The turf owners belted out duets at five times the normal rate. Such forceful protection of their habitat makes sense for the non-migrating birds, Mennill says. While their northern counterparts typically make new homes each year, for resident tropical songbirds, “There may be increased pressure to defend their territory.” Click the links below to listen to the wrens’ duets.

Wren duet 1
Wren duet 2

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