Biologists have identified two contenders for the title of the world’s loudest birds

The bare-necked bellbird and the red-legged seriem can produce calls with a peak volume exceeding 120 decibels. These figures were obtained by biologists who compiled one of the largest sets of field measurements of bird call volume.

The study by João Menezes and Jeff Podos has been published in the journal *Evolution*. The authors measured the amplitude of calls from 123 bird species in Brazil and the Amherst area in the US state of Massachusetts. For 113 of these species, such data had not previously been recorded.

Details

Measuring the volume of birds in the wild is more complicated than it seems: sound levels depend on the distance from the source. The researchers used high-precision portable sound level metres in conjunction with laser rangefinders, which allowed them to determine both the signal amplitude and the distance to the bird simultaneously.

The difference between the species studied reached approximately 58 decibels. At one end of the range were hummingbirds, with levels of around 64 dB — comparable in order of magnitude to normal conversation. At the other end were the bare-necked bellbird and the red-legged seriemas, whose peak values exceeded 120 dB.

This is a level which, in everyday terms, is usually compared to very loud machinery. However, such comparisons should be treated with caution: the perception of sound depends on distance, the duration of the signal and the method of measurement. The peak level of an individual bird’s call cannot be directly equated with prolonged exposure to industrial noise.

The results also revealed certain anatomical patterns. On average, larger birds were louder. The authors attribute this, in particular, to their massive musculature, which may enable a stronger compression of air.

Another predictor turned out to be beak opening: in loud species, it is wider on average. The researchers draw an analogy with the bell of a brass instrument — a wider opening may facilitate the effective projection of sound.

However, the study did not identify a single reason why certain species have evolved to produce extremely loud calls. The authors tested several hypotheses: that particularly loud birds are poorer flyers and compensate for their limited mobility with their voice; that they live in dense woodland, where it is harder to spot a mate; or that they are more likely to have a polygamous breeding system.

The data did not provide overall support for these assumptions. The example of the red-legged seriem is particularly telling: it inhabits open landscapes and forms monogamous pairs, even though it is one of the loudest species in the sample.

Why this is important

The authors cautiously name the collared bellbird and the red-legged seriemas as contenders for the title of loudest birds, rather than declaring a new, definitive record-holder. Previously, Jeff Podos and his colleagues measured a call of around 125 dB from the white-throated bellbird, which Guinness World Records recognised as the loudest recorded bird call.

Comparing records depends on which metric is used: the maximum call of a single bird or the typical values of several individuals of the same species. Therefore, the results of the new study are more significant as a comparative database than as a contest for the absolute record.

The main finding of the study is a significant expansion of data on the amplitude of bird calls and the identification of physical characteristics associated with loudness. Body size and the width of the beak opening help to explain how some birds produce such a powerful sound.

However, the question of why such extremely loud calls evolved remains open. The authors emphasise that data on a significantly larger number of species are needed to test ecological and evolutionary explanations.

Source

Phys.org: ‘Biologists may have discovered two of the world’s loudest birds’, 29 September 2026.

João C. T. Menezes, Jeffrey Podos. Study in the journal Evolution, 2026. DOI: 10.1093/evolut/qpag153.