The male white bellbird (Procnias albus), which lives atop mountains in the Amazon region of northern Brazil, is – for now at least – the loudest known bird in the world.
Its mating call recently was found to have a sound pressure more than three times that of the previous champion – its Amazonian colleague the screaming piha (Lipaugus vociferans) – and is much louder than a chainsaw or a rock concert.
It’s so loud, in fact, that researchers led by Jeff Podos from the University of Massachusetts Amherst, US, and Mario Cohn-Haft, from the Instituto Nacional de Pesquisas da Amazônia, Brazil, wonder how the “audience” can stand it.
“We were lucky enough to see females join males on their display perches,” says Podos. “In these cases, we saw that the males sing only their loudest songs.
“Not only that, they swivel dramatically during these songs, as to blast the song’s final note directly at the females. We would love to know why females willingly stay so close to males as they sing so loudly.”
There is some relief in the form of a trade-off, however. The louder the singing, the less time the singers can keep going.
Research into why these small birds can make such a loud noise is continuing.
Mario Cohn-Haft, the curator of birds at the National Institute of Amazonian Research in Brazil and one of the authors of the study, regularly travels to understudied rainforest areas to survey birds and other species. On a 2017 trip to the Serra do Apiaú, a peak in north Brazil, he encountered bellbirds, which tend to live at high altitudes. They are “the soundtrack of the mountain,” he said. “You can hear them from a mile away.”
While examining a bellbird specimen during that trip, Dr. Cohn-Haft was struck by the thickness of its abdominal wall. It had “this really ripped, washboard stomach,” he said. He thought it might have something to do with the loudness of their song — “if they didn’t have that kind of protection,” he said, perhaps “their guts would blow out.”
He sent photos to , a professor specializing in bioacoustics at the University of Massachusetts at Amherst, who was similarly intrigued. A year later, the two led a team that further studied the bird.
Until a few years ago, assessing the amplitude, or loudness, of birdsong required an unusual amount of devotion and tech-savvy. Only a couple of dozen species have been properly measured, said Dr. Podos.
But new tools are making the pursuit much easier. For their expedition in 2018, Dr. Podos and Dr. Cohn-Haft brought sound level meters more commonly used for industrial-noise monitoring, along with laser range-finders to pinpoint how far away the birds were.
