Home ranges of released West Indian manatees Trichechus manatus in Brazil

Abstract

The distribution of the Vulnerable West Indian manatee Trichechus manatus is influenced by physical and environmental factors such as water salinity, temperature and depth, freshwater supply and the availability of food resources. In Brazil, information on the habitat use of this species is insufficient for effective conservation. Here, we monitored manatees that had been found stranded as calves, rehabilitated in captivity and subsequently released, to identify their home ranges and examine their adaptation to life in the wild. The study, which involved monitoring six manatees using satellite and VHF telemetry systems, was conducted during 2016–2019 in the states of Paraíba, Sergipe and Bahia in north-eastern Brazil. Home range size of individuals was 2.56–42.07 km2 and all fidelity sites (areas used most frequently) were within protected areas. The longest distance travelled from the coastline upriver was 14.24 km and the longest distance offshore was 0.93 km. There were no significant differences in home range data between the dry and rainy seasons, but there was significant difference between the sexes, with males travelling across larger areas than females. All but one of the six individuals met the majority of indicators established in the Brazilian Manatee Reintroduction Protocol, and thus were considered to have successfully adapted to the wild. Our study provides information on patterns of habitat use and areas intensely used by manatees, which can assist protected area managers in defining priority areas for manatee conservation in Brazil.

Accomplishments and challenges of the research on Antillean manatee: A bibliometric analysis

“…These studies represent important baseline information for monitoring and management and are often based on simple methods to collect manatee information such as interviews of local inhabitants, detection of indirect signs of presence (feeding signs, feces), or fixed-point visual surveys from shore or floating platforms. Nevertheless, during the last decade, there has been an important increase of documents describing the utilization of more sophisticated monitoring tools, such as telemetry (e.g., Castelblanco-Martínez et al, 2013;Gonzalez-Socoloske et al, 2015;Normande et al, 2016;Attademo et al, 2022;dos Santos et al, 2022), side-scan sonars (e.g., Gonzalez-Socoloske et al, 2009;Gonzalez-Socoloske & Olivera-Gómez, 2012;Arévalo-González et al, 2014;Guzman & Condit, 2017;Castelblanco-Martínez et al, 2018;McLarty et al, 2020;Corona-Figueroa et al, 2021), drones (e.g., Ramos et al, 2018Ramos et al, , 2022Landeo-Yauri et al, 2020, and hydrophones (e.g., Kikuchi et al, 2014;Rivera-Chavarría et al, 2015;Merchan et al, 2019). Likely, in the upcoming years, the rapid evolution of detection and tracking devices -and the increase in their affordability -will have a positive impact on the amount and quality of data about Antillean manatee presence, movements, and habitat use in developing countries.…”

Behaviour and occurrence of the Antillean manatee (Trichechus manatus manatus) in relation to habitat characteristics and the influence of human activities in a protected area in north‐eastern Brazil

“…Clusters of wild and released animals have been previously reported in the area, with interaction between specimens (Luna et al, 2021). The interaction with wild manatees and/or other released manatees, as observed in the study, is considered one of the criteria for evaluating the success of the rehabilitation and release programme in Brazil (Santos et al, 2022).…”

“…The monitoring of captive and released individuals is carried out by the non‐governmental organization Aquatic Mammals Foundation (FMA), in partnership with the federal institution Aquatic Mammals Center (ICMBio/CMA) (Luna et al, 2021) and Integrated Management Center (ICMBio/NGI Mamanguape). Before release into the wild, manatees were marked by removing a tissue fragment from the caudal fin (cookie) and had a transponder (or microchip) with a unique number implanted (Normande et al, 2015; Borges et al, 2020; Santos et al, 2022). Such procedures enable individuals to be identified and their visual and remote monitoring in the wild (Luna et al, 2021).…”

“…Before release into the wild, manatees were marked by removing a tissue fragment from the caudal fin (cookie) and had a transponder (or microchip) with a unique number implanted (Normande et al, 2015;Borges et al, 2020;Santos et al, 2022). Such procedures enable individuals to be identified and their visual and remote monitoring in the wild (Luna et al, 2021).…”

“…Rehabilitated specimens have been released and monitored in the states of Alagoas, Ceará and Paraíba, for population restoration purposes (ICMBio, 2018;Luna et al, 2021). The Barra do Rio Mamanguape Environmental Protection Area (EPA), in Paraíba state, is one of the areas for manatee release (Silva et al, 2011;Luna et al, 2021;Santos et al, 2022). This EPA was considered the main stronghold and reproduction area of the Antillean manatee in northeastern Brazil (Paludo & Klonowski, 1999;Silva et al, 2011) and one of the protected areas with the highest densities of T. m. manatus in north-eastern Brazil (Alves et al, 2013;Alves et al, 2015), with up to 11 animals sighted concomitantly (Silva et al, 2011).…”