Natures wonders: the bowerbird concert hall (Introduction)

by David Turell , Monday, September 30, 2024, 16:29 (52 days ago) @ David Turell

New acoustic engineering found:

https://www.science.org/content/article/male-bowerbirds-build-acoustics-their-love-shri...

"Like architects behind the world’s great opera houses, male great bowerbirds build twiggy concert venues that amplify their raucous songs and make sure each note is pitch perfect to woo discerning females, according to a study published this month in Behavioral Ecology.

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"The mating rituals of male great bowerbirds (Chlamydera nuchalis) have long been a source of fascination. They gather materials from their wooded surroundings in northern Australia to construct tall, arching bowers. The structures consist of a thatched twig tunnel called an avenue, bracketed by courts decorated with pebbles, snail shells, bones, and colorful bits of glass or plastic.

"Males will advertise their venue with a loud, harsh call. If a female arrives for the show and enters his avenue, the showman will fly down into the court and turn on the razzle-dazzle. Singing a raspy, hissing song, he picks up various trinkets such as sticks and fruits and shows them to the female, who can only see the male’s head through the tunnel’s opening. He waves the objects and tosses them aside, turning around and flaunting the crown of pink feathers on the back of his head. If his audience is impressed, the pair mates in the avenue.

“'The females are sitting in this fixed audience position and the males are running around like crazy and throwing things in the air, making these—to our ears—horrendous screeching sounds,” Quigley says. Most research on the spectacle has focused on the visual aspects, she adds. So it’s great that the new study examines how the auditory experience factors in.

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"Male great bowerbirds, it turns out, are excellent sound engineers. The team found that the avenue’s shape amplifies the male’s song, making it louder for a female within. The court’s decorations also influence the acoustics, boosting the complexity of sound frequencies heard inside the avenue. Sound bouncing off the hard shells also cranked up the volume.

"Bowerbirds aren’t the only nonhuman animals that build sound-enhancing structures. For instance, mole crickets dig burrows that act like megaphones for their calls. Other species, such as some glass and rocket frogs, exploit features of their surroundings, bouncing their calls off leaf surfaces for extra volume. But the great bowerbirds’ engineering is unique, he says, as it tailors its sound effects to an audience inside the venue.

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"Quigley notes the males’ efforts also include dinner with their show. They paint the avenue walls with saliva and plant material, and females nibble on this while watching his performance—one more sensory experience that might sway her affections. “She’s provided with a little snack, like she’s got her popcorn in her movie seat.'”

Comment: like the weaverbirds, this is a complex behavior that strongly suggests it was supplied by design and not by a natural form of trial and error.