Vocal complexity in Antillean manatees (Trichechus manatus manatus)

Abstract

Vocal complexity can be expressed through variations in repertoire size, structure, and individual manatee repertoires. Here we aimed to assess the complexity of the vocal behaviour of Antillean manatees living in captivity (i.e., artificial pools) and in reintroduction enclosures (i.e., natural enclosures placed in an estuarine area). Specifically, we evaluated: (i) the structure of vocalisations to assess whether they had variants; (ii) the variation in call production (rate and pattern) between groups with different configurations; (iii) whether individuality occurred in vocalisation structure. We found four categories of vocalisations, of which two had different variants. Not all study groups produced all call categories and variants. Older and younger males in the reintroduction enclosures had the highest call rates compared to captive females and captive males. The vocal and behavioural patterns differed between groups. Squeak call structure differed between individuals. Such vocal complexity may aid manatees in adapting to their dynamic social and structural environment, facilitating communication.

Antillean manatee calves in captive rehabilitation change vocal behavior in anticipation of feeding

“…It's possible that one of the calves in our study only produced high squeaks while the older calf only produced squeaks. Alternatively, the structures and production rates of squeaks can vary across captive manatees of different groups, sexes, and age classes, as demonstrated by Umeed et al (2022).…”

“…Manatees vocalize to communicate with conspecifics and calves tend to vocalize 2–6 times more frequently than adults (O'Shea & Poché, 2006). Manatees can also alter frequency and temporal parameters of calls depending on the behavior they are engaged in (Brady et al, 2021; O'Shea & Poché, 2006) and produce calls of different structures and at different rates between sex, age groups, and individuals (Umeed et al, 2022). For example, Florida manatees produce calls that are longer in duration and more frequency modulated when animals are stressed (Brady et al, 2021).…”

Manatees display diel trends in acoustic activity at two microhabitats in Belize

“…Antillean manatees rely on sound to communicate [27][28][29]. Like most mammals, manatees vocalizations are produced by forcing air through their vocal folds [30].…”