Audible and Ultrasonic Vocalisations of Two Captive Stoats (Mustela Erminea): Structural Categorisation and an Open Annotated Dataset

Abstract

Stoat (Mustela erminea) vocalisations remain sparsely characterised, despite the species' significance as a major invasive predator in Aotearoa | New Zealand. Here, we describe the audible and ultrasonic vocalisations recorded from an adult male-female pair held in laboratory enclosures over three days, with blank-room control recordings. Audible calls attributed to the stoats were categorised into chitter, grunt, and hiss; the hiss is a narrowband c. 10 kHz tone of several seconds’ duration, consistent with early descriptive accounts. All ultrasonic calls were concentrated in the c. 22–28 kHz band. We provide a structural description of seven low-band ultrasonic call types and report their relative proportions. The annotated recordings are released as an open dataset to support downstream work on automated detection, acoustic lure development, and comparative bioacoustics. The behavioural context of the ultrasonic calls cannot be determined from the present design and warrants further investigation.