Amazon's male white bellbird dethrones the screaming piha as the loudest bird in the world
Amazon's screaming pihas are not the world's loudest birds anymore. They have been dethroned by another creature from Amazon: the dove-sized male white bellbird. Living in the mountains of northern Amazon, scientists from the University of Massachusetts Amherst and the Instituto Nacional de Pesquisas da Amazônia, Brazil, have recorded the birds during mating rituals, which, they claim is the loudest call ever documented.
According to lead author Jeff Podos, the songs from the male birds are so deafening that they reach decibel levels equal to the loudest human instruments.
The call is at least nine decibels (dB) louder than that of the piha, reaching volumes of 125 dB— a normal human voice is about 60 dB.
For their study, these researchers measured the bird's sound pressure using a new generation sound level meter and shot high-speed videos of the birds. They also factored in other adaptations such as breathing musculature, head and beak size, the shape of the throat and how these may influence the unusual aptitude the birds have for long-distance song transmission.
Studying anatomical features helped these researchers speculate the reason behind the birds' deafening calls. According to Vice, the bird’s unique anatomy, which developed as a result of its fruit-based diet, may be the key to their loud calls.
"These birds swallow large fruits whole and then just kind of sits there chewing until it regurgitates the seeds. This feeding strategy requires a large beak and tough digestive muscles, which are traits that may also lend themselves to producing the strange calls," reports Vice.
Their fieldwork in Amazon also paved way for observations that these researchers don't fully understand yet. While observing the female birds, they noticed that they willingly stayed close to males as they sang loudly. This got the scientists thinking as to how the females stayed at close-range without damaging their hearing.
Hazarding a guess, Podos says,"Maybe they are trying to assess males up close, though at the risk of some damage to their hearing systems."
Further, they stumbled upon something curious: they saw that as bellbird and piha songs were getting louder, they were also getting shorter.
"We don't know how small animals manage to get so loud. We are truly at the early stages of understanding this biodiversity," says Podos.
But they think this may be because the birds' respiratory systems have a finite ability to control airflow and generate sound.
Podos says their studies help us develop a better sense of bird communication and song. They also help us understand how structural divergence by natural selection in birds drives changes in the kind of songs they can sing and their social interactions.
In the future, Mario Cohn-Haft, the co-author of the study, wants to explore how the physical and anatomical structures and behaviors allow bellbirds to produce such loud sounds and how they endure them without hearing damage.
The study was published in Current Biology.