The influence of age and sex on the vocal repertoire of the Antillean manatee (Trichechus manatus manatus) and their responses to call playback

Abstract

Limited information is available regarding the acoustic communication of Antillean manatees, however, studies have shown that other manatee taxa produce vocalizations as a method of individual recognition and communication. Here, the acoustic signals of 15 Antillean manatees in captivity were recorded, aiming to (1) describe their acoustic repertoire, (2) investigate the influence of sex and age on vocalization, and (3) examine manatee responses to call playback. Six acoustic signals ranging in mean fundamental frequencies from 0.64 kHz to 5.23 kHz were identified: squeaks and screeches were common to adult males, adult females, and juveniles; trills were common to adult males and females; whines were specific to males; creaks were specific to females; and rubbing was specific to juveniles. The structure of squeak vocalizations was significantly different between age and sex classes and screech structure was significantly different between age classes. Squeaks and screeches produced by juveniles had higher frequencies of maximum energy when compared to those produced by adult males and females. A significant increase in the vocalization rate following vocalization playbacks was found for all three age/sex groups. Our results introduce the potential of using acoustic signals in identifying and noninvasively monitoring manatees in the wild in Brazil.

Behavior related vocalizations of the Florida manatee (Trichechus manatus latirostris)

“…Vocal repertoires are limited for rhinos and calls were observed in fewer social contexts such as mating, aggression, and during play (Policht et al, 2008). In addition to information related to age (Sousa‐Lima et al, 2002, 2008; Umeed et al, 2017), sex (Sousa‐Lima et al, 2008; Steel, 1982; Umeed et al, 2017), and individuality (Sousa‐Lima et al, 2008), manatee vocalizations contain motivational information in their calls. Results in this study are also similar to what has been reported for phylogenetically related species such as the African elephant.…”

“…Manatee vocalizations exhibit frequency modulations that can occur in the beginning, middle or end of the call (Nowacek et a l., 2003; O'Shea & Poché, 2006). Differences in structure in manatee vocalizations have been attributed to age (Sousa‐Lima et al, 2002, 2008; Umeed et al, 2017), sex (Sousa‐Lima et al, 2008; Steel, 1982; Umeed et al, 2017), and individuality (Sousa‐Lima et al, 2008). However, it has also been hypothesized that frequency modulations observed in manatee calls could be related to motivational state (O'Shea & Poché, 2006).…”

Elephants and Sirenians: A Comparative Review across Related Taxa in Regard to Learned Vocal Behavior

“…The vocal repertoire of Sirenians varies between three and six call types depending on the mode of classification (Anderson & Barclay, 1995;Brady et al, 2020;Steel, 1982;Umeed et al, 2018). However, for most species, we lack sufficient data to adequately characterize the breadth and function of their vocal repertoire.…”

Estado, desarrollo y tendencias de los estudios en acústica de la fauna en Colombia

“…Los resultados que encontramos para los órdenes Carnívora, Sirenia, Artiodactyla y Rodentia fueron muy escasos; esto evidencia un fuerte vacío en el conocimiento en órdenes con un gran potencial de trabajo (Lozano-Flórez et al, 2021). El comportamiento acústico puede proporcionar señales filogenéticas (Peters & Tonking-Leyhausen, 1999;Cap et al, 2008), estimar abundancias (Thompson et al, 2010), apoyar herramientas de reconocimiento individual Della Libera et al, 2015;Carlson et al, 2020), y por ende, brindar información sobre las poblaciones (Umeed et al, 2018) en especies difíciles de capturar o en categoría de peligro (p. ej., manatíes) en las que las herramientas acústicas tienen una ventaja más, al ser métodos no invasivos.…”