University of Massachusetts Amherst researchers found that two bird species produce calls louder than a jackhammer, challenging assumptions about which creatures make the planet’s most extreme sounds. The bare-throated bellbird and red-legged seriema both exceed 120 decibels, according to a study published Tuesday in the journal Evolution.
The findings show how incomplete our understanding of natural phenomena remains, even in relatively well-studied fields. From a standardized distance of 1 meter, researchers measured the bare-throated bellbird’s call at 122.4 decibels; one specimen reached almost 131 decibels. Two red-legged seriemas averaged almost 121 decibels.
Expanding the Decibel Rankings
The white bellbird has held the title of loudest bird call since 2019, when researchers recorded it screeching at up to 125 decibels and Guinness World Records certified the claim. Scientists had “a hunch” the bare-throated bellbird would rank highly because it’s a close relative of the white bellbird. The new research adds serious competition to that benchmark, though the measurement method determines which bird truly ranks loudest.
The gap between the loudest and quietest birds studied is staggering. The bare-throated bellbird’s call creates sound pressure 800 times that of the dusky-throated hermit, a hummingbird whose call measured only 64.1 decibels. Some of these birds outshout elephants, lions, and bison—animals much larger than they are.
Evolutionary biologist João C.T. Menezes conducted the research as part of his PhD with biology professor Jeff Podos. He explained how birds produce such extreme vocalizations. “Bigger birds have bulkier muscles, which are capable of creating greater internal pressures, which ultimately generate louder sounds,” Menezes said. “Broader mouths allow more energy to radiate into the environment.”
The Research Challenge
Field measurements pose practical problems. Exact distance matters because it affects apparent loudness, but researchers may hear birds before seeing them; the birds may fly away or “stop singing altogether out of shyness,” Menezes noted. To solve this, the team used laser range finders—tools golfers use to measure distance to a hole—and recorded distance and volume at the same time.
Between December 2018 and January 2025, researchers measured calls from 123 bird species in Massachusetts and Brazil. They had never recorded the calls of 113 species, a sign of how much basic data remains uncollected in biological research. After correcting for background noise and distance, the team compared sound readings with data on body size and open beak width. Larger species and birds with broader mouths tended to sing louder.
The data raises questions about what drives these differences through evolution. Menezes expected bellbirds to call loudly because they live in forests and are polyamorous, potentially needing to communicate through dense woodland and attract multiple mates. But red-legged seriemas are “strictly monogamous” and typically live in open habitats, where extreme volume shouldn’t offer obvious survival advantages. Researchers couldn’t conclusively identify the environmental and evolutionary factors behind the differences.
“Despite recording the amplitude of many birds’ calls, ‘it’s such a tiny fraction still,’” Menezes said. “There’s so much to answer yet.”
Catherine Sheard, an interdisciplinary fellow at the University of Aberdeen in Scotland who didn’t take part in the study, reflected on ongoing discovery. “It doesn’t surprise me that even a relatively modest survey of volume has newly identified some very loud birds,” Sheard told CNN. “As fieldworkers continue to collect more data on avian sound, I would predict that even more ‘loudest’ birds will be identified in the future.”
Why This Matters:
This research shows both the promise and the limits of scientific inquiry. Researchers are identifying biological phenomena that remained unknown despite decades of ornithological study: 113 bird species in this sample had never been acoustically recorded. The findings show that scientists need comprehensive baseline data before drawing firm conclusions about nature’s extremes. Yet researchers still can’t explain why strictly monogamous birds in open habitats produce extreme volume, suggesting that understanding of evolutionary mechanisms remains at an early stage. The study also shows how methodological innovation matters: laser range finders, readily available tools, enabled findings that earlier field techniques couldn’t achieve. Researchers measured calls from 123 bird species between December 2018 and January 2025.