Researchers at the University of Massachusetts Amherst measured the bare-throated bellbird’s call at 122.4 decibels from one meter away, adding another contender to the human-made ranking of the world’s loudest birds. The red-legged seriema also sings above 120 decibels, according to a study published Tuesday in the journal Evolution. Neither bird claims a clear-cut champion’s slot. The answer shifts with the method used to measure loudness.
“The nearest comparison in everyday sounds would be a jackhammer,” study co-author and evolutionary biologist João C.T. Menezes told CNN. He carried out the research for his PhD alongside his former teacher, biology professor Jeff Podos.
Who Gets to Be “Loudest”
Researchers averaged the bare-throated bellbird’s 122.4-decibel reading over a 20 millisecond time block at a standardized distance of one meter, or 3.3 feet. Its sound pressure measures 800 times that of the quietest species recorded, the dusky-throated hermit, a hummingbird whose call reached 64.1 decibels.
One bare-throated bellbird, though, delivered the study’s loudest individual call, reaching almost 131 decibels across one meter. Average the noisiest calls from all birds over a 20 millisecond block, and the red-legged seriema ranks first, at almost 121 decibels among two birds. Across calls, the white bellbird leads in average peak volume, at 127 decibels among six birds.
“The world’s loudest bird depends on how one defines ‘loud,’ underscoring the difficulties in measuring loudness,” evolutionary biologist Catherine Sheard, an interdisciplinary fellow at the University of Aberdeen in Scotland who wasn’t involved in the study, told CNN. The ranking depends on the measurement and the birds included; no single title stands uncontested.
The Instruments Behind the Ranking
From December 2018 to January 2025, researchers measured vocalizations from 123 bird species in Massachusetts and Brazil. A university statement said they had never recorded the calls of 113 of those species before. Field measurements pose a challenge: readings depend on a bird’s distance, and a bird may be heard before it’s seen, fly away, or “stop singing altogether out of shyness,” Menezes said.
Researchers used laser range finders—the tools golfers use to measure distance to a hole—to record distance and song volume at the same time. They corrected for background noise and distance, then compared sound readings with data on body size and open beak width. Larger species and birds with broader mouth openings tended to sing louder.
“Bigger birds have bulkier muscles, which are capable of creating greater internal pressures, which ultimately generate louder sounds,” Menezes said. He also said “broader mouths allow more energy to radiate into the environment.” Still, some birds sing louder than far larger animals, including elephants, lions and bison. Another mechanism behind birds’ volume remains undiscovered.
What the Study Can’t Settle
Researchers couldn’t conclusively identify the environmental and evolutionary factors that led some birds to call more loudly. Menezes said they expected bellbirds to be loud because they live in forests and are polyamorous, and might need to communicate through dense woodland and mate with as many birds as possible. Red-legged seriemas challenge that explanation. Menezes described them as “strictly monogamous” and said they typically live in open habitats.
“Despite recording the amplitude of many birds’ calls, ‘it’s such a tiny fraction still,’” Menezes said, adding, “there’s so much to answer yet.” Sheard said even a relatively modest survey of volume had identified very loud birds for the first time, and predicted that fieldworkers will identify more “loudest” birds as they gather more data on avian sound.