Datasets for "Greater Japanese horseshoe bats (Rhinolophus nippon) gradually converge their echolocation call frequency to colony members"

Datasets for "Greater Japanese horseshoe bats (Rhinolophus nippon) gradually converge their echolocation call frequency to colony members"

In bats using constant-frequency (CF) echolocation calls, it is known that call frequencies vary among colonies and across geographic regions, and between sexes. In this study, we investigated frequency changes of second harmonic of CF component (CF2) following the mixing of resident and wild-caught populations of greater Japanese horseshoe bats (Rhinolophus nippon). By focusing on individual-level frequency adjustments in the context of colony mixing, we tracked CF2 frequencies in a total of 101 individuals across 15 capture events over a one-month period after mixing event, based on long-term husbandry records. When CF2 frequencies initially differed between the two populations, intergroup frequency differences gradually decreased after mixing, accompanied by a reduction in overall variability within the colony. This convergence was achieved asymmetrically, with lower-frequency individuals primarily adjusting their frequencies upward, while higher-frequency individuals showed little or no change. No systematic changes were observed when initial frequencies did not differ between two groups. Echolocation in group contexts would be expected to suffer from severe acoustic interference caused by overlapping calls from conspecifics; however, CF bats instead tend to converge on a shared CF frequency. Because this convergence was primarily driven by individuals using lower frequencies, it may be interpreted as a strategy to allow individuals to share a “silent spectral window” above the CF2 frequency, which is critical for Doppler-based detection. In other words, for CF bats, in which the use of Doppler information is fundamentally important, frequency convergence may function as a strategy for avoiding acoustic interference.