Why Do Some Birds Sing Louder Than Others? A Global Study Has Answers
Global comparative analysis finds song amplitude varies between and within species, shedding light on avian communication and evolutionary trade-offs
Volume matters in the world of birdsong
A comprehensive new study has revealed that birds differ not only in what they sing but also in how loudly they sing – with significant variation in song amplitude observed both across species and within species. Published in Philosophical Transactions of the Royal Society B, the study analysed data from over 170 bird species worldwide to understand the evolutionary, ecological and morphological factors influencing birdsong loudness.
The research, led by Henrik Brumm and colleagues, marks the first large-scale comparative analysis of birdsong amplitude. It demonstrates that song loudness is not random but instead shaped by a combination of physical constraints, behavioural adaptations and environmental pressures. While many studies have focused on pitch, tempo and complexity in birdsong, this study turns the spotlight to a less-examined but ecologically vital parameter: how loud birds actually sing.
Who sings loudest – and why
Among the loudest singers were members of the Thraupidae (tanagers), Icteridae (New World blackbirds), and some suboscine lineages, with certain species exceeding 100 dB SPL at close range – comparable to a chainsaw. Meanwhile, many small passerines produced songs at much lower intensities, typically below 80 dB SPL. Crucially, the study found that song amplitude was not solely determined by body size.
While larger birds tended to produce louder songs, this relationship was modest, and several small-bodied species defied expectations with unexpectedly high amplitudes. Vocal loudness was also found to correlate with beak morphology, song type and social ecology, with birds that use their songs for long-range communication or territorial advertisement often singing louder than those relying on close-range cues.
Birds balance sound with trade-offs
Producing loud sounds carries costs. The researchers note that high-amplitude vocalisations may increase predation risk, require more energy, or reduce vocal control. Some species appear to compensate through vocal learning or changes in posture and respiratory support when singing.
Intra-specific variation was also explored. Within species, individuals often modulate their song amplitude in different contexts, such as singing more loudly in noisy urban environments – a phenomenon known as the Lombard effect. Yet, the study found that baseline amplitude also varies between individuals, suggesting a mix of innate, physiological and behavioural factors at play.
Implications for understanding avian communication
The findings underscore the importance of including amplitude in analyses of bird communication. Louder songs are likely to travel further and be more effective in attracting mates or repelling rivals – but they may also be more conspicuous to predators. This trade-off may help explain why birds evolve different ‘volume strategies’ in different ecological contexts.
Furthermore, by highlighting the limitations of using relative amplitude or uncalibrated recordings in bioacoustic studies, the authors call for more widespread use of calibrated amplitude measurements. They also advocate for integrating amplitude into models of signal evolution and acoustic niche partitioning.
New frontiers in birdsong research
This study opens the door to future investigations into how environmental noise, habitat structure and social behaviour influence vocal output. It also raises intriguing questions about the role of sexual selection in favouring louder – or more controlled – song, and how this intersects with energy budgets and life history strategies.
As Brumm and his co-authors conclude, amplitude is a fundamental but underexplored aspect of birdsong. By bringing volume into focus, this work helps build a more complete picture of how birds communicate – and how their messages are shaped by the pressures of ecology, evolution and physiology.
August 2025
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