West Indian manatees in Brazil 943 Zelinha’s home range, including five fidelity sites, was
2.83 km2. This manatee mainly visited Coqueirinho Beach to the north, the mouth of the Camurupim River, and Croa do Meio, reaching 4.85 km upstream and 0.54 km from the coast (Fig. 1f). Males Astro and Puã had the largest home ranges, and
females Tita and Zelinha had the largest number of fidelity sites. All fidelity sites were within protected areas (in estu- aries, bays or upstream on the river). Integrating data from all manatees monitored, we
mapped the main areas used by the animals. In Paraíba, they mainly used two rivers: Mamanguape and Paraíba. In the estuary of the Mamanguape River, the manatees trav- elled up to c. 10 km upstream from the mouth. Two of the five animals monitored in Paraíba (Mel and Puã) made trips from the Mamanguape River to the beaches of the Cabedelo municipality, c. 28 km away. There, the animals used the es- tuary of the Paraíba River and one of its tributaries (Guia River), reaching up to 7.71 km upstream, and frequently used the coastal areas. Reefs, which reduce the effects of waves and currents (Barbier et al., 2011), are found at both locations. The animals ventured up to 0.68 km offshore, but did not use the open sea beyond these reef formations. In Sergipe and Bahia, Astro mainly used the estuaries of the Vaza Barris River in Sergipe and the Piauí/Fundo/Real estuarine complex, on the border between the two states, travelling c. 37.23 km between these two areas. There were no significant differences between the dry
and rainy season ranges of four manatees (Astro, Mel, Puã and Zelinha; Mann–Whitney: U= 67;P = 0.57) throughout the monitoring period (Table 2). There was, however, a significant difference in the home range size of individual manatees (Kruskal–Wallis: H(3) = 9.86;P = 0.01), and males had significantly larger home ranges than females (Mann– Whitney: U= 19;P = 0.01). During the study period, some individuals exhibited
symptoms of illness or injury (Table 3). Three (Mel, Puã and Zelinha) had a mild nasal secretion that did not re- quire medicinal intervention and resolved before the end of the study period. Puã also exhibited gastrointestinal pro- blems, which regressed spontaneously. Astro,Mel and Puã had injuries caused by trauma (some sustained in colli- sions with motorized watercraft) and were submitted to an individual evaluation and therapeutic protocol. Tita, who had a similar haematological pattern as the other an- imals,was found dead at BoaVista Port in February 2018 in a tributary of the Mamanguape River. The necropsy re- vealed faecaloma, pulmonary embolism and cardiopul- monary arrest. Manatees used freshwater sources 1–11 times per month
in the dry season and 1–12 times per month in the rainy season. There were no significant differences among indi- viduals (Kruskal–Wallis: H(2) = 1.201;P = 0.54) or between seasons (Mann–Whitney: U= 718.5;P = 0.06; Table 4).
Discussion
The manatees monitored in this study used estuarine areas more intensely than the open sea. The same pattern was reported for 20 manatees released along the coast of north- eastern Brazil (Normande et al., 2016), which used the estuarine environment with greatest intensity, followed by mixed habitats and the marine environment, suggesting that this preference may be linked to sources of freshwater in estuaries. The use of upstream areas of rivers varied by individual,
with some travelling up to 14 km upstream. These move- ments are believed to be motivated by the search for sources of freshwater, as reported in previous studies (Ross, 2007; Castelblanco-Martínez et al., 2012; Normande et al., 2016). Astro, Mel and Puã travelled the longest distances, and
these travels were always between two estuaries. Some of the individuals we monitored had been studied previously. De Lima & de Passavante (2013) reported three fidelity sites used by Astro during 1994–2004: Maré Mansa beach in Alagoas during the early post-release period, and the estuar- ies of the Vaza Barris River and Piauí/Real/Fundo complex, both in Sergipe. Sixteen years later (our study), he still used the estuary of the Vaza Barris River, but his fidelity sites were in the Piauí/Real/Fundo estuarine complex. Normande et al. (2016) analysed the home range of four
individuals monitored in this study (Mel, Puã, Tita and Zelinha) during November 2008–June 2013. Compared to this earlier period, the home ranges of Mel, Tita and Zelinha decreased by 0.42, 2.09 and 3.82 km2, respectively, whereas Puã’s home range increased by 2.02 km2. The re- ductions in home range size may indicate that the animals identified the best feeding sites after 2013 and subsequently did not need to travel as far in search of food. Tita, Yara and Zelinha have remained within the limits of the Mamanguape River estuary since their release. De Lima et al. (2012) observed similar behaviour, with released mana- tees staying near their release site. We did not record any of the individuals studied in areas
beyond the reef barrier, but it is believed that manatees use these areas as corridors for movements between estuaries (de Lima et al., 2012; Normande et al., 2016). Paludo & Langguth (2002) reported similar findings from a study of native manatees in the state of Rio Grande do Norte. The fact that there are few GPS locations recorded from these areas may also be linked to water depth and animal move- ments, as manatees use open waters for fast movements between estuaries, during which the transmitter remains mostly submerged and thus no signal is transmitted (Edwards et al., 2016). The fidelity sites identified in this study were in sheltered
areas with low incidence of waves and currents (estuaries, bays and areas protected by reefs), which demonstrates the importance of such areas to manatees. Similar findings
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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