Temporal and Spectral Variation in Advertisement Call of Males Microhyla achatina (Tschudi, 1838) are Sufficient For Individual Discrimination

Animals that live in the socially complex environment would inevitably interact either with other conspecific and/or heterospecific animals. For some beneficial purposes, animals inhabit such environment should be able to recognize or distinguish their surrounding individuals based on particular properties of signals in order to minimize the risk of aggressive response especially to any organism who do not pose a major threat. A signal property emitted by frogs in a population could be used as a recognition cue if the values of the property exhibit greater variation among individuals than within individual. The objective of this research was to examine the individual variation in advertisement call and to investigate the contribution of some acoustic properties to the individuality of Microhyla achatina (Tschudi, 1838). All acoustic properties analyzed in this study exhibit a high level of within and among individuals variation except for dominant frequency. Variations among individuals for all properties were more variable than within individuals. This result demonstrated that the acoustic properties examined here could be used to evaluate individuality in M. achatina. Our Discriminant Function Analysis (DFA) showed that individual male M. achatina could be distinguished statistically by their advertisement calls in which 88% of calls were assigned to the correct individual. The acoustic properties that contributed most toward individual discrimination were call duration, pulse duration and dominant frequency. In conservation point of view, the differences of acoustic properties among frogs could be used as an alternative method of recognizing a single individual. The use of bio-acoustics tool for monitoring the population of certain species is certainly not dangerous due to it is a non-invasive method, hence the application of this method is strongly suggested especially for some species that are threatened and endangered.