[CLIP: Loud bird call]

That incredibly loud song soaring over the quieter birds in the Amazon rain forest belongs to the male white bellbird. At 125 decibels, his short but startling songs are louder than a jackhammer.

“The white bellbird may be the loudest bird in the world. These birds are making extraordinarily loud noises. Noises that are so loud, they would be harmful to our hearing if you had to hear them up close.”

Mario Cohn-Haft, curator of birds at Instituto Nacional de Pesquisas da Amazônia. He and his colleague Jeffrey Podos recorded the birds in their natural habitat. Their findings are in the journal Current Biology. [Jeffrey Podos and Mario Cohn-Haft, Extremely loud mating songs at close range in white bellbirds]

Birds like the kakapo and the Moluccan cockatoo have also laid claim to the loudness title. But the researchers think the new study has better instrumentation and data than anything previously published in the scientific literature.

“Loud sounds are usually for long-distance communication. And then, when the listener is up close, the volume is dropped way back down. But in the case of the white bellbird, the opposite seems to be true. The loudest sound they make is actually reserved for courting a female. When the female comes in close, they just switch to their loudest sound and do it right in her face.”

The male displays another feature—an extendable wattle. It looks like a worm hanging from above the bird’s beak. 

“When they do their loudest song, which is this fast, two-note ‘bong bong’ that they do, the first bong looking away from the female with their back to her. And then swing around right into her face with that second note. And that wattle whips around, and I suspect that if she were too close, she would get it in the face.”

Most birds have paper-thin abdominal muscles. But the half-pound bellbird, roughly the size of a common city pigeon ...

“... had a washboard stomach—this incredible thick set of muscles rippling all along its abdomen.”

The powerful muscles provide lots of singing power. But the mating song is short and sweet ...

[Clip: Bong bong]

... because:

“A very loud sound like that has to be really short for the bird to be able to do it at all.”

—Eliene Augenbraun

[The above text is a transcript of this podcast.]