Western Gorilla Vocal Repertoire and Contextual Use of Vocalizations

Abstract

Despite considerable interest in the vocal communication of non‐human primates and its possible relevance to theories of language evolution, we know surprisingly little about how vocal communication varies between closely related species inhabiting differing environments. Here, we provide the first quantitative description of the vocal repertoire, calling rates, and call usage in wild western gorillas and compare it to the previous work on mountain gorilla vocal behavior. During 1572 h of focal follows (n = 533), we collected behavioral data on and recorded vocalizations (n = 2163) of eight individuals in one group at Mondika Research Center (Republic of Congo). We supplemented these data with opportunistic recordings of an additional adult male in a second group. We used discriminant function analysis to test how well calls can be categorized by their acoustic structure and used behavioral data to determine the typical usage of western gorilla call types. The vocal repertoire comprised of 17 call types. Twelve of 17 call types were given primarily in a single context. Our results were similar to previous studies of mountain gorillas in that grunts, and grumbles were used most frequently and the silverback male vocalized more frequently than other group members. However, compared to mountain gorillas, western gorillas used an additional call type (sex‐whinny), used a second call type (hoot series) in a completely different context and by all age–sex classes, and used many more call types in a more context‐specific fashion. Our study suggests that although vocal production is highly constrained by morphology and phylogeny, differing social and ecological conditions can yield differences in the use and function of calls, even between two closely related species such as western and mountain gorillas.

Learned vocal and breathing behavior in an enculturated gorilla

“…Salmi et al 2013) and the context in which they were performed (e.g., directed into a telephone or combined with particular learned manual gestures). In general, the behaviors appeared to be performed intentionally, but they were not necessarily communicative, nor were they necessarily associated with a salient sound.…”

Where Apes and Songbirds are Left Behind: A Comparative Assessment of the Requisites for Speech

“…Linguists estimate that while the Oxford English Dictionary defines over 600,000 separate words, the average native English-speaking university graduate's repertoire contains around 20,000 word families (i.e., excluding archaic words, proper names, compound words, abbreviations, alternative spellings, and dialect forms; Goulden, Nation, & Read, 1990;Nation & Waring, 1997). By comparison, great apes, parrots, and a representative songbird, black-capped chickadees (Parus atricapillus) are estimated to have repertoire sizes of under 100 distinct vocal types, where a "type" could be a call or song (e.g., bonobos, Bermejo & Omedes, 1999;mountain gorillas, Fossey, 1972;chimpanzees, Goodall, 1986;lowland gorillas, Harcourt, Stewart, & Hauser, 1993;Salmi et al, 2013;parrots, Bradbury, 2003;black-capped chickadee, Ficken, Ficken, & Witkin, 1978). With the exception of more prolific oscine songbirds like the nightingale (Luscinia megarhynchos), with a repertoire containing over 200 elements due to song syllables (Kipper, Mundry, Sommer, Hultsch, & Todt, 2006), typical ape, songbird, and parrot distinct vocalization repertoires are within the same order of magnitude as that of the European badger (Meles meles), a vocal non-learning social mammal (Wong, Stewart, & MacDonald, 1999), and two orders of magnitude smaller than the repertoire size (synonymous with vocabulary) of humans.…”

Acoustical Variation and Contextual Specificity of a Gorilla Vocalization: A Case Study

“…For instance, the vocal types which are produced by western lowland gorillas are similar to those of mountain gorillas [3,4], and a great degree of vocal uniformity is also characteristic for different sub-species of chimpanzees [5][6][7] and orang-utans [8]. Species with vocal learning abilities, on the other hand, such as song birds, can add new and drop old vocal types, rendering their vocal repertoire particularly flexible [as, for instance, sedge warblers, see 9].…”