Behaviour and vocalization of Mongolian gazelle (Procapra gutturosa) in rutting harems considering the sex-specific vocal anatomy.

We investigated behaviour and vocalization of wild-living male and female Mongolian gazelles during the winter rutting period, occurring at low temperatures, on average − 21.7˚C. We used both manual and automated audio recordings and manual video recordings of calling animals in rutting harems. Recording vocalizations with automated devices placed within harems documented a high vocal activity during the rut in both sexes. Harem males produced their series of rutting barks day and night. Video recordings revealed larynx retraction at each bark resulting in substantial vocal tract elongation. Harem females produced various contact calls but did not produce barks. Both sexes produced nasal alarm snorts and oral running calls, with widely open mouth during galloping. Mating behaviour and fights between rival males were not accompanied by any calls. Both male rutting barks and female contact calls were unusually high-frequency for animals of such size. We integrated data on behavioural postures and acoustic variables with data on sex-specific vocal anatomy, obtained during dissections of male and female specimens. We showed that Mongolian gazelle is the only studied ruminant, in which flexible vocal folds were evolutionarily lost. For both male and female larynges, we report the lack of any thin and flexible, rostrally directed mucosal parts in the glottal region suggesting that Mongolian gazelle, contrary to most other mammals, do not produce their calls by expiratory airflow-induced vocal fold vibration. The production mechanism of the high-frequency calls in Mongolian gazelle remains unclear. We discuss the evolution of vocal rutting behaviour in polygynous Mongolian gazelles.