940 S. S. dos Santos et al.


later moved to larger pools with other calves. They are fed soya milk formula, algae and seagrass. At 1 year of age they are moved to an oceanarium and offered a diet of sea- grass and algae supplemented with vegetables (carrots and lettuce) and vitamins (Normande et al., 2015). After rehabilitation and following the Brazilian Manatee


Reintroduction Protocol (de Lima et al., 2007), the animals are transferred to enclosures in theMamanguape River estu- ary or Tatuamunha River, within two marine protected areas (MamanguapeRiver EnvironmentalProtectionArea inParaíba and Environmental Protection Area Costa dos Corais in Alagoas, respectively). Manatees spend 15 days–12 months in these areas, adapting in captivity (i.e. enclosureswithin estuar- ies) to local environmental conditions (Normande et al., 2015). The Manatee Reintroduction Programme was created in


1994 with the purpose of re-establishing the original geo- graphical distribution of the manatee in Brazil (de Lima et al., 2007). As a result of this initiative, the number of rescued and rehabilitated manatees increased during 1994–2020,with a total of 48 manatees released (de Lima et al., 2012;Normande et al., 2016, 2019). These efforts to rehabilitate and release stranded manatees have facilitated the reconnection of iso- lated populations and the restocking of areas where manatees historically occurred (Normande et al., 2016). Upon release, manatees tend to use estuarial and coastal


areas (Normande et al., 2016). Based on their movement patterns, the area used by released individuals, expanding over time from their respective release sites, is conceptually defined as their home range, and the extreme geographical positions reached during movements constitute the limits of their territories (de Lima et al., 2012). Data on habitat use and movement patterns, gathered


as part of release and reintroduction programmes, provide insights into movements, ecological aspects and impacts of human activities, which can facilitate the conservation of species and habitats (Normande et al., 2016). Considering the ecological importance of manatees (Aquasis, 2016), their vulnerability and the threats to which they are exposed (de Lima et al., 2011), further studies on their distribution and home ranges are warranted. Mapping habitat use patterns, themost used resources, home ranges and the routes and cor- ridors used between these areas is important for manatee conservation. This information can help identify priority areas for habitat protection and assist in mitigation of an- thropogenic impacts. It may also help improve manatee re- habilitation strategies based on the influence of captive management on post-release behaviour. The aim of our study was to identify the home ranges of released manatees in Brazil and evaluate their adaptation to life in the wild.


Study area


We tracked the movements of rescued, rehabilitated and released manatees in the north-eastern Brazilian states of


Paraíba, Sergipe and Bahia (Fig. 1). In Paraíba, manatees mainly use the estuary of the Mamanguape River in the municipality of Rio Tinto and the estuary of the Paraíba do Norte River, between the municipalities of Cabedelo and Lucena, where the Cabedelo Port is located, which has con- siderable motorboat traffic. In Sergipe and Bahia, the study areas were in the estuary of the Vaza Barris River and the Piauí-Fundo-Real estuarine complex. The Piauí River is 132 km long and flows into the Atlantic ocean between the municipalities of Estância (Sergipe) and Jandaíra (Bahia). The climate in the area is characterized by a dry (September– February; mean monthly rainfall 62 mm) and rainy (March– August; mean monthly rainfall 262 mm) season.


Methods


Manatee tracking Six manatees (named Astro, Mel, Puã, Tita, Yara and Zelinha) that had been released during 1994–2012 (de Lima et al., 2012; Normande et al., 2016) were monitored by the Aquatic Mammal Foundation during 2016–2019 (Table 1). The tracking apparatus consisted of a belt attached to each animal’s caudal peduncle, a tether (flexible nylon rod attaching the belt to the transmitter housing; de Lima et al., 2007) and a radio transmitter (Nortronic/Aquatic Mammals Foundation, Natal, Brazil). The transmitting assemblage consisted of a GPS device to record geographi- cal coordinates, a satellite transmitter programmed to send signals every 3 hours through the Globalstar network (Globalstar, Covington, USA), and a conventional VHF transmitter operating continuously to transmit locations in real-time (Borges et al., 2020). An experienced team periodically captured the released


manatees during periods of low tide for clinical manage- ment and deployment of the satellite tags. The animals were captured with a custom-made 150-m long net deployed in a circle from a boat. Prior to fitting the tracking equip- ment, they were evaluated clinically, and biological samples and biometrics were collected (White & Francis-Floyd, 1990). Captures for clinical management occurred every 6 months or according to the needs of individual animals (de Lima et al., 2007). When lost transmitters needed to be replaced or adjustments made to the belts because of changes in the animal’s weight, this was done by diving or by recapturing the animal.


Data collection


We received information on the location of individuals (date, time and geographical coordinates) from the satellite system on a daily basis, and downloaded the data through the Globalstar system via e-mail, a smartphone application or the system’s digital platform. We used the VHF system to


Oryx, 2022, 56(6), 939–946 © The Author(s), 2022. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S003060532100079X


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