Male Painted Turtles Call More Variably Than Females, Study Finds

Turtles, long thought of as silent animals that rely on visual and chemical signals, may be doing more talking than scientists realized. A new study of the Midland Painted Turtle (Chrysemys picta marginata) documents five distinct call types in adult turtles and reveals that males and females use these sounds differently depending on who else is nearby.

Researchers recorded turtle behavior and vocalizations during 35 hours of one-hour trials. The experimental setup included solitary individuals as well as paired interactions between two males, two females, and mixed-sex pairs.

Acoustic traits varied across social contexts, meaning that the same turtle did not sound the same in every situation. Most striking was the discovery of one call type produced exclusively by males, a pattern that hints at a sex-specific signaling function. Males also showed greater within-individual variance in their acoustic traits than females did, meaning a given male’s calls were less consistent from one instance to the next than a female’s.

That variability matters because signaling theory offers a specific prediction about it. Under intrasexual selection, in which members of one sex compete with each other for access to mates, signals can evolve to be condition-dependent: their expression flexes with the signaler’s physical state, fighting ability, or motivation. The authors caution that they cannot definitively identify the function of turtle vocalizations, but they note that the greater within-male variation they observed is consistent with this condition-dependent signaling hypothesis.

The study also comes with an important caveat about its own design. Some of the males in the experiment experienced different pre-treatment conditions before the trials began, and the researchers acknowledge that these differences may have affected the vocalization patterns they recorded.

Perhaps the most unexpected finding came from counting interactions. Vocalization rates were negatively correlated with the number of close social interactions between turtles. In other words, the more time animals spent in tight, close-range contact, the less they vocalized. The researchers interpret this as evidence that vocalizations are used at a distance, while visual, tactile, or potentially chemical cues take over when turtles are within touching range.

The findings add to a growing recognition that acoustic communication is far more widespread in animals than classic textbooks once suggested. Although turtle signaling has been considered primarily visual and chemical, many species are now known to vocalize across multiple life stages, from embryos inside eggs to hatchlings and adults.

Why does this matter beyond turtles? Understanding how acoustic traits vary with context is a first step toward decoding function.

The researchers frame their results as an opening move rather than a conclusion. Because the study could not definitively establish function, the authors are careful to present their interpretations as theory-guided possibilities rather than proven mechanisms.

Each of these findings gives researchers a testable target in a group where vocal behavior has been largely overlooked, and each brings the field a step closer to understanding what turtles are actually saying to one another beneath the water’s surface.

Subject of Research: Sex differences and social context effects in the vocalizations of adult Midland Painted Turtles

Article Title: Sex differences in turtle vocalizations: social context and behavioural roles

Article References: Voss, C., Rollinson, N., & Lacroix, C. (2026). Sex differences in turtle vocalizations: social context and behavioural roles. BMC Ecology and Evolution. https://doi.org/10.1186/s12862-026-02602-z

Image Credits: AI Generated

DOI: 10.1186/s12862-026-02602-z

Keywords: turtle vocalizations, acoustic communication, Midland Painted Turtle, social context, condition-dependent signaling, intrasexual selection, animal behavior, Chrysemys picta, sex differences, freshwater turtles, call types, behavioral ecology