Home ranges of released West Indian manatees Trichechus manatus in Brazil

Sebastião Silva Dos Santos,Vanessa Araujo Rebelo,Iara Dos Santos Medeiros,José Eduardo Mantovani,Raphael Dantas Círiaco,Allan Oliveira Barreto Carvalho,Ryan Emerson Gomes Dos Santos,Jean Paul Dubut,Miriam Marmontel,Iran Campello Normande,João Carlos Gomes Borges,Thalma Maria Grisi Velôso

doi:10.1017/s003060532100079x

Abstract

AbstractThe 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.

Highlights

IntroductionThe West Indian manatee Trichechus manatus is categorized as Endangered on the Brazilian Red List (ICMBio, ) and as Vulnerable on the IUCN Red List (Deutsch et al, )
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
The West Indian manatee Trichechus manatus is categorized as Endangered on the Brazilian Red List (ICMBio, ) and as Vulnerable on the IUCN Red List (Deutsch et al, )

Summary

Introduction

The West Indian manatee Trichechus manatus is categorized as Endangered on the Brazilian Red List (ICMBio, ) and as Vulnerable on the IUCN Red List (Deutsch et al, ). Manatees prefer naturally sheltered areas such as coves, bays and estuaries and are sensitive to disturbance caused by the construction and operation of cities, ports, marinas, shipyards, salt works, shrimp farms and other anthropogenic structures and activities in these areas (Aquasis, ). Such habitat modifications are associated with an increase of manatee calf stranding events along the north-eastern Brazilian coast (Parente et al, ; Meirelles, ; Medeiros et al, ). After an initial health assessment, they are kept in individual pools for a quarantine period of c. months, and

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