Two bird species produce calls exceeding 120 decibels, louder than a jackhammer and comparable to sounds made by some of the planet’s largest animals. Researchers at the University of Massachusetts Amherst identified the bare-throated bellbird and red-legged seriema as the second- and third-loudest birds ever recorded, according to a study published Tuesday in the journal Evolution.
From a standardized distance of 1 meter, the bare-throated bellbird’s call measured 122.4 decibels, averaged over a 20 millisecond time block. One specimen hit almost 131 decibels. The two red-legged seriemas in the study averaged almost 121 decibels. Their calls produced sound pressure 800 times greater than that of the dusky-throated hermit, a hummingbird whose call measured just 64.1 decibels—the quietest species in the research.
“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 during his PhD with biology professor Jeff Podos, his former teacher.
The Ranking Shift
Seven years ago, Guinness World Records named the white bellbird the bird with the loudest call, at up to 125 decibels. It now shares the podium. Which bird counts as “loudest” depends entirely on how researchers define the measurement. Average the noisiest calls from all studied birds, and the red-legged seriema ranks first at almost 121 decibels. Compare peak volume instead, and the white bellbird leads at 127 decibels across six birds.
Evolutionary biologist Catherine Sheard, an interdisciplinary fellow at the University of Aberdeen in Scotland who wasn’t involved in the study, acknowledged the difficulty. “The world’s loudest bird depends on how one defines ‘loud,’ underscoring the difficulties in measuring loudness,” she told CNN.
A Decade of Field Research
Between December 2018 and January 2025, the research team measured vocalizations from 123 bird species across Massachusetts and Brazil. Researchers had never recorded the calls of 113 species—a significant gap in scientific knowledge about avian biology. Measuring bird-call volume in the field has always posed practical obstacles. Scientists need a bird’s exact distance to determine its apparent loudness, but a bird may call before it’s seen, fly away, or “stop singing altogether out of shyness,” Menezes explained.
The team used laser range finders—devices golfers use to measure distance to a hole—to track distance and bird-song volume at the same time. Researchers corrected for background noise and distance, then compared sound readings with data on body sizes and open beak widths. The pattern was clear: larger species and birds with broader mouth openings sang louder.
“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.” Yet some birds sing louder than much larger animals, including elephants, lions and bison. Another, still-undiscovered mechanism may enable these vocal feats.
The Evolutionary Mystery
Why some birds evolved such extraordinary vocal capacity remains largely unexplained. Researchers expected bellbirds to call loudly because they inhabit forests and are polyamorous, potentially needing to communicate through dense woodland and reach multiple potential mates. The red-legged seriema, though, presents a puzzle: they’re strictly monogamous and typically live in open habitats, so they lack the same apparent evolutionary incentive to be loud.
“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 predicted that as fieldworkers continue collecting data on avian sound, “even more ‘loudest’ birds will be identified in the future.” The research reveals how much remains unknown about animal biology, even in well-studied groups.
Why This Matters:
This research exposes a significant knowledge gap in our understanding of animal biology and evolution. Scientists studied birds for centuries without systematically measuring acoustic output across species—a foundational metric for understanding communication, mating behavior, and ecological adaptation. The fact that researchers had never recorded the calls of 113 of the 123 species studied shows how incomplete our baseline scientific knowledge remains.
For conservation and environmental protection, understanding how species communicate and adapt to their habitats is essential. The research also demonstrates the value of sustained, well-funded fieldwork and interdisciplinary approaches to answering fundamental questions about the natural world. When public investment in science is limited, entire dimensions of ecological knowledge go unmeasured, with implications we may not fully appreciate until gaps in that knowledge affect species survival or ecosystem health.