2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
New Zealand scientists studied the communication of male bats of the species Mystacina tuberculata and came to the conclusion that individual differences in the characteristics of their "singing" serve as a way of self-identification. An article in Behavioral Ecology and Sociobiology reports that the length of individual syllables, for example, was negatively correlated with arm length, an objective measure of individual size.
In addition to primates (especially humans), birds are considered the most "talkative" higher animals: they use vocalization in order to warn of danger, tell about the whereabouts of food, or attract a female. Among representatives of some species, singing is also common among females: gray junco, for example, sing "out of jealousy" to designate territory in front of an enemy female.
Vocalization of other animals has been studied relatively rarely. For bats, which live mainly in the dark, however, sounds are the main method of transmitting information: they use them both to communicate with relatives and to orientate in space using echolocation. Bats also use "singing" during the mating season, but little is known about the characteristics and features of such communication.
Cory Toth and Stuart Parsons from the University of Auckland decided to study the features of vocalization of male New Zealand bats. To do this, they recorded the "conversations" of 16 males and classified the resulting recordings according to the types of sounds depending on the frequency characteristics: trills (frequency change within 20 kilohertz), tones (constant frequency), down-frequency signals and up-frequency signals. The combinations of these sounds were singled out in 51 syllables.
Frequencies (over time) of different sounds: trill, tones, rise and fall
Having analyzed both the frequency and temporal characteristics of the syllables used by each individual, the scientists calculated the coefficients of the deviation of the sound characteristics of one individual (SDi) and among all individuals (SDb). The SDb to SDi ratio turned out to be more than one: this means that the individuals differed in vocalization more than within one individual. According to scientists, this result can be used as a potential way to distinguish each individual "by voice".
Further, the scientists traced the relationship between the sound characteristics of the vocalization of males and their physical parameters, namely, the size of the wing (it positively correlates with the overall size of the individual). It turned out that males with a smaller wing differ in much (p <0.042) longer syllables, consisting of a combination of trill and uplift.
The authors of the work concluded that the individual characteristics of vocal communication in male New Zealand bats are an honest and objective indicator of their merits over the female during the mating season. In addition, males themselves can identify each other with the help of singing.
It is curious that the identification of individuals by voice is not the only feature of the communication of bats, similar to the communication of other higher animals, including humans. For example, Israeli scientists recently discovered that Egyptian flying dogs (Rousettus aegyptiacus) can learn language from unrelated flock members.
