Johnnie Johnson, a current student on the Postgraduate Certificate in Ecological Survey Techniques, has contributed new observations that challenge long-held assumptions about the behaviour of one of Britain’s most familiar reptiles.
Britain’s reptiles are often thought of as silent creatures, relying on camouflage and stillness rather than sound. While vocal communication is well known in some lizard groups, such as geckos, it has rarely been associated with the UK’s native species. New observations, however, suggest that one of our most familiar reptiles may not be as quiet as we once believed. This observation forms part of Johnnie’s wider research interest in overlooked behavioural traits of Britain’s reptiles, particularly where applied ecological work intersects with fundamental natural history.
In August 2023, during a reptile translocation linked to a housing development in Brightlingsea, Essex, Johnnie observed several common lizards (Zootoca vivipara) producing short, chirp-like sounds when disturbed. The sounds were heard immediately before handling, as lizards became aware of human presence, and again following release at the receptor site. Notably, no vocalisations were heard during direct handling itself.
The calls were brief, lasting less than half a second, and had a high-pitched, chirping quality, reminiscent of a small bird or shrew. At the same time, the lizards showed clear changes in behaviour, including body stiffening, increased alertness, and rapid movement. Both males and females were present, although it was not possible to determine which individuals were producing the sounds.
These observations are significant because vocalisation has not previously been documented in Zootoca vivipara. Communication in lizards is usually associated with visual displays, such as posture or colouration, and chemical cues. The apparent use of sound, even subtly, suggests that acoustic signals may play a role alongside these better-known forms of communication.
The timing of the calls points towards a possible alarm function. Short, sharp sounds produced during moments of perceived danger could help alert nearby individuals to a threat. This idea fits with what we know about the social behaviour of common lizards, which can occur in relatively dense colonies and have recently been shown to construct communal hibernation cells.
Although the vocalisations were not recorded, these observations highlight how much remains to be discovered about even well-studied British species. In an increasingly noisy human world, it is easy for such faint sounds to go unnoticed, raising the possibility that acoustic behaviours in small, familiar species have simply been overlooked rather than absent. Importantly, they also demonstrate the scientific value of careful observation during applied ecological work, such as mitigation and translocation.
This finding has since been published in The Herpetological Bulletin, but it also raises broader questions. How common is vocalisation in Britain’s reptiles? What role does sound play in their social lives? And how many other behaviours are waiting to be discovered simply by paying closer attention? If vocal behaviour proves more widespread, it raises the intriguing possibility that bioacoustic surveys, already widely used for bats, birds, amphibians, and even some moth species, could one day help detect the presence, or cautiously infer the absence, of reptile species.
As with much of natural history, the answers may begin with listening more carefully, even to species we think we already know.
Learn more: 2025 Autumn issue (174) of The Herpetological Bulletin
