Vocalization Development in the Ussurian Tube-Nosed Bat Murina ussuriensis during Postnatal Growth, Including Calls for Responses between Mothers

Postnatal growth and vocalization development in the Ussurian tube-nosed bat Murina ussuriensis were investigated under captive conditions. Response calls between mothers and their young were also analyzed. Parturition occurred in early June. At birth, forearm length averaged 12.7 mm, and body weight averaged 1.43 g. The newborn young opened their eyes around five days after birth. From days five to 20, their forearm length and body weight grew noticeably. The calls of newborns had a peak frequency (PF) of 42 kHz and lasted 14 ms, while nursing females had a lower PF of 27 kHz. The females also used these calls to respond to their young. As the young grew, the PF of their short calls increased rapidly from 12 to 23 days of age and reached 68 kHz at 31 days of age. The duration of these calls decreased rapidly from three to 23 days of age and then gradually decreased to 2.5 ms, similar to adult echolocation calls. When the mother bat made echolocation calls, the young quickly responded by emitting isolation calls. As the young grew, the PF of their calls changed to around 35 kHz, which was lower than that in short calls. Published online 5 August, 2024; Print publication 31 October, 2024