Researchers at the University of Massachusetts Amherst measured the bare-throated bellbird’s call at 122.4 decibels from one meter, while the red-legged seriema ranked first under another measure of loudness. Published Tuesday in the journal Evolution, the findings add two contenders to the ranking of the world’s loudest birds.
“The nearest comparison in everyday sounds would be a jackhammer,” study co-author and evolutionary biologist João C.T. Menezes told CNN. He conducted the research for his PhD with his former teacher, biology professor Jeff Podos.
How the calls were measured
The study recorded vocalizations from 123 bird species in Massachusetts and Brazil between December 2018 and January 2025. A university statement said researchers had never recorded calls from 113 of those species before.
Field measurements can be tricky. Researchers need to know how far away a bird is because distance affects how loud its call seems. But a bird may call before it’s seen, fly off, or “stop singing altogether out of shyness,” Menezes said.
To measure distance and song volume at once, researchers used laser range finders—the tools golfers use to measure the distance to a hole. They corrected readings for background noise and distance, then compared the results with data on body size and open beak width.
The researchers averaged the bare-throated bellbird’s 122.4-decibel measurement over a 20-millisecond time block. Its sound pressure was 800 times that of the quietest species recorded, the dusky-throated hermit, a hummingbird whose call measured 64.1 decibels, the study said.
Different measures, different winners
One bare-throated bellbird produced the loudest individual call, reaching almost 131 decibels across one meter. But when researchers averaged the noisiest calls of all studied birds over a 20-millisecond time block, the red-legged seriema ranked first, at almost 121 decibels among two birds.
The white bellbird took the top spot when researchers averaged the peak volume reached by calls. Across six birds, it measured 127 decibels. Researchers found in 2019 that the white bellbird screeched at up to 125 decibels, and Guinness World Records named it as having the loudest bird call.
“The world’s loudest bird depends on how one defines ‘loud,’ which highlights the difficulties in measuring loudness,” evolutionary biologist Catherine Sheard told CNN. She’s an interdisciplinary fellow at the University of Aberdeen in Scotland and wasn’t involved in the study.
What the study can and can’t explain
Larger species and birds with broader mouth openings tended to sing louder, researchers found. “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,” he added.
Some birds can sing louder than much larger animals, including elephants, lions and bison, researchers noted. They said scientists still haven’t discovered another mechanism that enables birds to produce such loud calls.
Researchers couldn’t conclusively identify the environmental and evolutionary factors behind louder calls. Menezes said they expected bellbirds to be loud because they live in forests and are polyamorous, potentially needing to communicate through dense woodland and mate with as many birds as possible.
The red-legged seriema complicates that explanation. It’s “strictly monogamous” and typically lives in open habitats, Menezes said, so it doesn’t share those proposed reasons for calling loudly. “Despite recording the amplitude of many birds’ calls, ‘it’s such a tiny fraction still,’” Menezes said. “There’s so much to answer yet.” Sheard expects fieldworkers to identify additional loud birds as they collect more data on avian sound.