Bioacoustics of Microhyla berdmorei

Natural history notes. Microhyla berdmorei sensu stricto inhabits various types of moist evergreen forests, including monsoon and perennial rainforest types. It is generally associated with hilly regions and is often found near streams; it also occurs in secondary forests. Specimens of this species are active day and night, often hiding in the leaf litter on the forest floor. When disturbed, they make extraordinary long and vigorous jumps to escape. In Assam State , India , breeding activity typically occurs in still pools between October and November ( Garg et al. 2019 ; IUCN 2022). The noisy rasping call of M. berdmorei sensu stricto can be heard at night from beside forest pools; we have observed specimens of this species displaying cephalic amplexus (Fig. 7 A ). In India , Garg et al. (2019) recorded specimens from thickly vegetated swampy areas near the water bodies, either inside secondary forests or adjacent to human settlements. In Lawachara N. P., Bangladesh , Hakim et al. (2020) found M. berdmorei on trails, roads, and leaf litter in mature forests, degraded forests, tea plantations, and village habitats. Microhyla berdmorei coexists with M. mymensinghensis Hasan et al., 2014 in the northeastern (Dinajpur, Parbatipur) region of Bangladesh ( Hasan et al. 2014 ). This species was found either in the grass below large trees, referred to as “ Lendi Korui ” by the locals, or in expansive fields with some vegetation and somewhat damp and loose soil. Indigenous to the region, this species is commonly referred to as “ Boro Laubichi Bang ”, and its diet mostly includes ants and other small insects ( Hasan et al. 2014 ). In Mizoram , India , the species prefers waterbodies with sandy to gravel bottoms for breeding ( Raj et al. 2023 ).

Advertisement call. The male advertisement call of M. berdmorei represents a series of short rasping sounds resembling the sound of a ratchet. In an unpublished doctoral thesis, Lalremsanga (2011: 102) provided a description of the advertisement call for the M. berdmorei population from Mizoram , Northeast India . The call series consisted of one to seven calls emitted at a 3 s interval; a single call series lasted for 1.4– 1.6 s . Each call consisted of 7–12 pulses and lasted for 0.2 s at an interval of 0.06 s . The amplitude of the call increased slowly and reached a peak in the middle, which then decreased slowly until the end. The frequency spectra ranged between 1484 and 2046 Hz, with the dominant frequency being 1677 Hz. Our recording of male advertisement call series of M. berdmorei from Aizawl, Mizoram State , India , consisted of several calls (2–5; average 3.6 ± 1.2) emitted at a 2.5 ± 0.2 s (1.47– 3.20 s ) interval. A single call lasted for 0.20 ± 0.07 s (0.12–0.33) on average. Each call consisted of 11 ± 2.0 (9–13) pulses emitted at an interval of 0.06 s . The call’s amplitude increased slowly and reached a peak in the middle of the call, after which it gradually decreased; thus, each call’s relative amplitude profile has a symmetrical shape (Fig. 10 A ). The peak frequency of a call comprised 1892 ± 82 Hz (1781–1969 Hz), which is notably higher than the earlier estimates of Lalremsanga (2011) .