The pressure of sexual selection made peacocks gorgeous, tree shivers loud and birds of paradise great dancers. At first glance, the white bell tower does not seem to have benefited in a similar way. Breasted with barrels and big lips, long hair hanging from the tip of his beak, this rainforest bird looks more like a muppet than a Casanova bird.
But everyone has their own thing. According to a paper released Monday in Current Biology, this goofball boasts the most powerful bird songs ever made. And he should be proud of that because he sings the most piercing note right in the faces of potential friends.
Mario Con-Haft, Curator of Birds at the National Institute for Amazonian Research in Brazil and one of the authors of the study regularly travels to poorly explored areas of tropical forests to study birds and other species. While traveling in 2017 to Serra do Apiaú, a peak in northeastern Brazil, he came across bells that tend to live at high altitudes. They are "the soundtrack of the mountain," he said. "You can hear them from a mile away."
While exploring the image of a bell during this trip, Dr. Con-Haft was struck by the thickness of his abdominal wall. There was "this really torn, steel pool," he said. He thought it might have something to do with the thunder of their song – "if they didn't have that protection," he said, maybe "their gut would explode."
He sent photos to Jeffrey Podos, professor specializing in bioacoustics at the University of Massachusetts in Amherst, who was also intrigued. A year later, the two headed a team that further studied the bird.
Until a few years ago the assessment of the amplitude or strength of a bird's song required an unusual dose of devotion and technical skill. Only a few dozen species have been properly measured, said Dr. Podos.
But new tools make it much easier to pursue. For their 2018 expedition, Dr. Podos and Dr. Con-Haft brought in sound level meters, more commonly used to monitor industrial noise, along with laser rangefinders, to determine how far the birds were.
At the top of the mountain, they measured two vocalizations made by the white bell: a longer, more complex song, and a shorter, more intense one.
The second type of white bellboy song is stronger than a jackmaker and approaches, "at its peak, the amplitude of a pile driver" – about 125 decibels, Dr. Podos said. This makes it three times more intense than the call of the screaming drones, the previous sound recorder.
The researchers also found a compromise between the length and the amplitude of the song – the more intense the peak of the song, the less time it lasted. "If sexual selection continues to push the song stronger and stronger, it will become shorter and shorter," says Dr. Podos.
This, along with the simplicity of the song, is in line with "a model of evolutionary commerce – deviations between the amplitude of the sound and the complexity of the song," says Gonzalo Cardozo, a researcher at the University of Porto who did not participate in this study.
There remains a great mystery: The white bell sings its melody when a potential mate is near, begins with a face to it, and then rolls around to blow the strongest, record-breaking note right in her face. This expert in choreography puzzles: Many other birds, including birds the rather sophisticated satin bird actually announces its displays after a female shows interest in not shaking her.
Bellbird's strategy goes against expectations "Dr. Podos." They really look socially awkward. " "I'm surprised the strongest bird makes loud noises when the female is so close," says Nicole Creanza, an assistant professor at Vanderbilt University who is not involved in the study. She said the findings were contrary to her expectations, but called them "a great base for future research."
Podos hopes to find out if this behavior actually helps male birds make friends.
"We have never seen copulation – we have never seen what a really good man does," he said. "The ones we saw may have just been the losers."