ECHOLOCATION CALLS OF Myotis alticraniatus (CHIRROPTERA: VESPERTILIONIDAE) IN VIETNAM

Myotis alticraniatus is a small mammal species with widespread distribution in Vietnam and other Asian countries. However, prior to the present study, its echolocation calls were poorly documented. Between 2018 and 2020, we conducted bat surveys in Cat Ba National Park and other areas of Vietnam. Echolocation calls of the species were obtained in different recording situations: handheld, flying inside a fight tent and foraging in natural habitats. The average initial frequency (iFM) and terminal frequency (tFM) of this species’ echolocation calls are in ranges of 113.2-140 kHz and 57.8-68.6 kHz, respectively. Its call duration is in a range of 1.6-3.9 ms. When detecting an object or prey in natural habitats, the species emitted echolocation calls in groups of up to 10 signals with the iFM and tFM values in ranges of 60.6-64.3 kHz and 28.2-31.0 kHz, respectively. Results from the present study exhibited a wide variation in frequencies and signal shapes of the species echolocation calls.