Vocalisations of captive Sumatran tigers (Panthera tigris sumatrae)

Wild tigers (Panthera tigris) are endangered with populations continuing to decline primarily due to humans. Acoustic communication research is a recommended enhancement to current tiger conservation efforts. Tiger acoustic communication research is extremely limited with a solitary study quantifying a single tiger call. This study investigated the acoustic characteristics and behavioural context of tiger vocalisations. Remote audio recordings of five captive Sumatran tigers (Panthera tigris sumatrae) in two separate enclosures at Taronga Zoo, NSW Australia were obtained March-July 2014 and reviewed with sound analysis software. Tigers were most vocal between 0100-1100 hours. From peak vocalisation times, 547 high quality recordings of tiger vocalisations were separated into seven vocalisation types (‘moan’, ‘arf’, ‘mrr’, ‘chuff’, ‘growl’, ‘roar’, and ‘hiss’). Tiger experts provided suggested contexts and functions for these vocalisations. Classification of frequent laryngeal sounds including moan, arf, and mrr were verified with a multinomial logistic regression based on peak frequency (Hz), fundamental frequency (Hz) and duration (s) measurements. This research represents the first quantitative study of multiple tiger vocalisations. Descriptive literature on tiger communication lacks ‘mrr’ and ‘arf’ descriptions and acoustic characteristics of tiger vocalisations. Future research is needed to standardize vocalisation terms and further quantify the tiger vocal repertoire.