Vocal behaviour and intraspecific call variations of Kempholey Night Frog (Nyctibatrachus kempholeyensis) in the Western Ghats, India

Abstract

Signal analyses, basic call descriptions and call variations are the basis for assessing repertoires of individuals and species and also play a role in understanding social and breeding behaviour of frogs. The primary objective of this study was to describe call structure and repertoire of Nyctibatrachus kempholeyensis and to quantify call properties. The secondary objective was to investigate potential sources of variability of these properties, and thirdly to examine individual variations in their vocalisation both within and among individuals. The study was based on a sample of 627 calls recorded and analysed from 30 individuals in Mavingundi, Uttar Kannada, Karnataka State, India. The vocal repertoire of Nyctibatrachus kempholeyensis consists of two call types: a shorter and rarer Call B type and a more common and complex Call A type with two different notes in it. Temperature did not affect any of the measured call properties, neither other environmental variables, but body weight and SVL had statistically significant influence on call duration, Note 2 duration, silent interval and call rate. Silent interval, inter-note interval and dominant frequency of Note 1 were classified as dynamic call property, while all other call traits were intermediate. The ratios of among-individual to within-individual variability were greater than 1.0 which can indicate individual recognition cue. Dynamic call properties can reveal information on mate quality, however silent interval and call rate are generally dependent on motivation and disturbance. Differences among individuals in their acoustic behaviour might be important in determining their success in attracting a mate, but correlations between male mating success and call behaviour is difficult to detect.