Water limitation modifies vocal performance in California mice: implications for acoustic communication under environmental stress.

In arid environments or during prolonged drought periods, maintaining hydration becomes increasingly challenging, often requiring organisms to reduce investment in costly behaviors. Vocal performance is sensitive to hydration status because systemic dehydration can alter vocal fold mechanics and reduce vocal efficiency. In many mammals, vocalizations are produced when expiratory airflow induces self-sustained vibration of the vocal folds, making this mechanism vulnerable to systemic water imbalance. This study tested whether dehydration alters singing rate and acoustic song parameters in adult California mice (Peromyscus californicus). Mice were recorded over three days of water deprivation. Baseline variation was first assessed in a control group of ten animals with unrestricted water access; vocal activity and seven acoustic parameters showed no consistent daily trends. Vocal activity and acoustic parameters were then evaluated in 14 mice subjected to 72 h of water deprivation. Vocal activity did not decline during dehydration. Fundamental frequency, sound intensity, and syllable repetition rate decreased significantly during late-stage dehydration but recovered toward baseline after water restoration. Changes in fundamental frequency and sound intensity are consistent with altered vocal fold biomechanics associated with reduced tissue hydration, whereas reduced syllable repetition rate without changes in syllable duration suggests an additional effect on temporal control of vocal output. These findings demonstrate that systemic dehydration affects multiple components of vocal production and that vocal performance recovers following rehydration.