Characterising the vocal repertoire of the Indian wolf (Canis lupus pallipes)

Abstract

Vocal communication in social animals plays a crucial role in mate choice, maintaining social structure, and foraging strategy. The Indian grey wolf, among the less studied subspecies, is a social carnivore that lives in groups called packs and has many types of vocal communication. In this study, we characterise harmonic vocalisation types in the Indian wolf using howl survey responses and opportunistic recordings from captive and nine packs (each pack contains 2-9 individuals) of free-ranging Indian wolves. Using principal component analysis, hierarchical clustering, and discriminant function analysis, we found four vocal types using 270 recorded vocalisations (Average Silhouette width Si = 0.598) which include howls and howl-bark (N=238), whimper (N=2), social squeak (N=28), and whine (N=2). Although having a smaller body size, Indian wolf howls have an average mean fundamental frequency of 0.422KHz ({+/-}0.126), which is similar to other Holarctic clade subspecies. The whimper showed the highest frequency modulation (37.296{+/-}4.601 KHz) and the highest mean fundamental frequency (1.708{+/-}0.524 KHz) compared to other call types. Less information is available on the third vocalisation type, i.e. Social squeak or talking (Mean fundamental frequency =0.461{+/-}0.083 KHz), which is highly variable (coefficient of frequency variation = 18.778{+/-}3.587 KHz). Our studys characterisation of the Indian wolfs harmonic vocal repertoire provides a first step in understanding the function and contextual use of vocalisations in this social mammal.