From a modest chirp to an ear-splitting call: in 123 bird species, body size and bill width together prove to be the main factors associated with how loud they can be.
Larger birds and species with a wider bill gape can generally call more loudly than smaller birds. This emerges from sound measurements taken on 123 bird species, in which maximum sound levels ranged from 64.1 decibels in a hummingbird to 122.4 decibels in the bare-throated bellbird (Evolution, 29 September). The latter and the red-legged seriema join the white bellbird as candidates for the title of loudest bird in the world.
Two American researchers measured bird sounds between 2018 and 2025 in the United States and Brazil, using sound level meters to determine sound pressure and laser rangefinders to measure the distance to the calling bird. The values were corrected for background noise and converted to a standard distance of 1 metre.
Between the quietest and loudest species there was a difference of 58.3 decibels; in terms of sound pressure, the maximum of the loudest species was more than eight hundred times as high. Body size and bill gape width in particular were associated with a higher maximum sound level. A wider bill may allow more sound energy to escape, whilst larger birds may have more powerful respiratory muscles, among other advantages. For flight mobility, habitat and mating system, the researchers found no clear association with maximum sound level.
How large the differences sound can be heard below for four species from the study.
Bare-throated bellbird (Procnias nudicollis)
At 122.4 decibels at 1 metre, this species produced the highest measurement in the study. Together with the white bellbird and the red-legged seriema, it is a candidate for the title of loudest bird in the world.
Red-legged seriema (Cariama cristata)
This large South American bird also exceeded 120 decibels. Averaged across the measured individuals, it actually achieved the highest maximum sound level: 120.9 decibels. The species is monogamous and lives in open terrain – amusingly, precisely two characteristics for which the researchers found no clear association with maximum sound level.
Carolina wren (Thryothorus ludovicianus)
The call of this North American wren is, according to the researchers, roughly as loud as a human shout. That places it well below the extreme bellbirds and red-legged seriema, yet it still sounds remarkably powerful for such a small bird.
Black-capped chickadee (Poecile atricapillus)
This small North American songbird was among the quieter species measured by the researchers. Even so, its call is, according to the researchers, roughly as loud as a blender.
