First record of underwater sound produced by the Balkan crested newt (Triturus ivanbureschi)

This study presents first evidence for underwater sounds produced by adult Balkan crested newts (Triturus ivanbureschi). Recordings were made in spring of 2019 in controlled laboratory conditions using a commercially available omnidirectional hydrophone connected to a linear PCM recorder. A total of 27 animals (21 males, 6 females) were recorded under different conditions: (a) alone in an empty tank, (b) alone in a tank full of vegetation, and (c) a pair in an empty tank. Results indicated that both male and female newts produced a click-like sound with a mean duration of 34 ms (± 5.31 SD; range: 27-51) and mean peak frequency of 1887 Hz (± 405 SD; range: 1162-2770). Not all newts tested produced sounds and there were no statistically significant differences between males and females or recordings under different conditions in terms of click number, duration and frequency parameters, with the exception of the ratio of peak frequency/bandwidth at 50% peak amplitude, which was lower for clicks produced in the vegetated tank. Newt snout-vent length and body mass also had no effect on any of the studied parameters. The obtained results suggest that clicks could have a function in orientation and exploratory behaviour.