Song structure and sex-specific features in the indris

Abstract

In the dense tropical rainforests of Madagascar, visual communication is impeded by obstacles. Lemurs use scent marking to communicate at a short distance and loud calls to communicate at a long range. The Indri (Indri indri) is a diurnal primate that emits choruses of three distinct types. The song types are essential in advertising position within the group territory, in deciding the sorts of aggressive group encounters, and in maintaining cohesion between animals dispersed during feeding. A detailed examination of the advertisement songs showed that three main parts constitute them. The last, most consistent of these parts, showed phrases consisting of units emitted with a descending frequency. The rhythm of these units changed significantly between phrases of different durations and the sexes. We also found that the unit structure may provide conspecifics with information on the individual identity of the emitter and that male songs, but not female's, are more similar to those of their parent of the same sex than to other indris. The song of the indris is an effective way to transfer information at a long distance and may transmit sex and individual identity information.

The Natural History of Musical Rhythm: Functional and Mechanistic Theories on the Evolution of Human Rhythm Cognition and the Relevance of Rhythmic Animal Behaviors

“…In chimpanzees, both males and females engaged in such rhythmic behaviors, whereas for the great majority of other species where rhythmic output has been described-almost exclusively in the form of vocalizations-this phenomenon is typically restricted to males (as reviewed in sections 2.1. and 4.1). Based on extant data, the vocalizations of some primate species-such as titi monkeys, tarsiers, and indris-could be an exception to this male bias (Caselli et al, 2014;Clink et al, 2020;de Gregorio et al, 2021;Gamba et al, 2019). Although we found that male chimpanzees performed rhythmic behaviors more often than female chimpanzees, the social efficacy of these behaviors did not seem to differ between sexes, displaying similar levels of social influence on conspecifics .…”

“…Acoustic analyses of rhythmic features have recently been conducted on the calls of several marine mammal species (humpback whales : Schneider & Mercado, 2019;killer whales: Kello et al, 2017; Northern elephant seals: Mathevon et al, 2017;harbor seal: Ravignani, Kello, et al, 2019), birds (e.g., Kello et al, 2017;Roeske et al, 2020), andprimates (e.g., de Gregorio et al, 2021;Gamba et al, 2019;Schruth et al, 2021;Terleph et al, 2017). Comparative studies that include multiple species are also underway.…”