Researchers at the University of Massachusetts Amherst found that the bare-throated bellbird and red-legged seriema sing above 120 decibels, adding two contenders to the ranking of the world’s loudest birds. The study appeared Tuesday in the journal Evolution.
“The nearest comparison in everyday sounds would be a jackhammer,” study co-author and evolutionary biologist João C.T. Menezes told CNN. Menezes did the research for his PhD with his former teacher, biology professor Jeff Podos.
How the Calls Were Measured
From a standardized distance of 1 meter (3.3 feet), the bare-throated bellbird’s call measured 122.4 decibels, averaged over a 20 millisecond time block. The study says that sound pressure is 800 times that of the quietest species recorded: the dusky-throated hermit, a hummingbird whose call measured 64.1 decibels.
Which bird ranks loudest depends on the measurement. One bare-throated bellbird produced the study’s loudest individual call, reaching almost 131 decibels across 1 meter. Researchers averaged the noisiest calls of all the studied birds over a 20 millisecond time block, and the red-legged seriema came first, at almost 121 decibels among two birds. Average peak call volume put the white bellbird first, at 127 decibels across six birds.
“The world’s loudest bird depends on how one defines ‘loud,’ which shows 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.
In 2019, researchers found that the white bellbird could screech at up to 125 decibels. Guinness World Records then crowned it as having the loudest bird call. Researchers had “a hunch” the bare-throated bellbird would rank highly because it’s a close relative of the white bellbird.
A Wider Survey of Birdsong
Between December 2018 and January 2025, researchers measured vocalizations from 123 bird species in Massachusetts and Brazil. A university statement said researchers had never recorded the calls of 113 species before.
Field measurements pose practical challenges. Researchers need to know a bird’s distance because that affects its apparent loudness. But a bird may be heard before it’s seen, then fly away or “stop singing altogether out of shyness,” Menezes said. To measure distance and volume at the same time, the researchers used laser range finders, tools golfers use to measure the distance to a hole.
Researchers corrected for background noise and distance, then compared sound readings with data on the birds’ body sizes and open beak widths. 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 added that “broader mouths allow more energy to radiate into the environment.”
What Researchers Still Don’t Know
Some birds sing louder than much larger animals, including elephants, lions and bison. Researchers said that points to another, still-undiscovered mechanism that enables birds to produce loud calls.
Researchers couldn’t conclusively identify the environmental and evolutionary factors behind louder calls. Menezes said they expected bellbirds to call loudly because they live in forests and are polyamorous, and might need to communicate through dense woodland and mate with as many birds as possible. But loud red-legged seriemas are “strictly monogamous” and typically live in open habitats, Menezes said, so they don’t share those reasons to be loud.
“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 a relatively modest survey of volume had identified new very loud birds. She predicted that fieldworkers will identify more “loudest” birds as they collect more data on avian sound.