West Indian manatees in Brazil 941
FIG. 1 The study area in north-eastern Brazil (AL, Alagoas; BA, Bahia; PB, Paraíba; PE, Pernambuco; SE, Sergipe), where six released West Indian manatees Trichechus manatus were monitored during 2016– 2019. (a) Astro’s home range in the Piauí/Fundo/Real rivers estuarine complex and at the mouth of the Vaza Barris River, (b) Mel’s and (c) Puã’s home ranges at the mouths of the Mamanguape and Paraíba Rivers, (d) Tita’s home range in the Mamanguape River, (e) Yara’s and (f) Zelinha’s home ranges at the mouth of the Mamanguape River.
visually locate individuals during fieldwork, to collect data on behaviour, areas used and interactions with people. Field sur- veyswere conducted daily,with observers travelling on foot, by car or in small motorboats. Data collected included geograph- ical location, name of the site, identification of the individual, transmitter number, water depth, distance to high tide line, weather and tidal conditions, visibility, behaviour of the indi- vidual, presence of people and type of any interaction, and composition of the research team. Each hour of monitoring included 15 minutes of behaviour observation. Locations were visualized using QGIS 3.10 (QGIS Development Team, 2019), resulting in the identification of the main areas used by each individual monitored, in the dry and rainy seasons. We used the Home Range tool in QGIS to calculate the areas of use, defining an animal’s home range as the area containing 95% of the locations obtained; this excludes sporadic displacements that are not considered as part of the individual’s home range (Normande et al., 2016). We had sufficient data to calculate home ranges in the dry and rainy seasons for four individ- uals: Astro, Mel, Puã and Zelinha. We used a Kruskal–Wallis test to examine any dif- ferences in the home range (response variable) among
individuals (Astro, Mel, Puã and Zelinha; categorical vari- able), and Mann–Whitney tests to examine any differences between seasons (dry and rainy) and sexes (male and fe- male). When there were significant differences, we used Dunn’s post hoc test to identify heterogeneous groups. All tests were performed in R 3.5.0 (R Core Team, 2018). Weused the kernel estimator to calculate the home range
(95% kernel) of each animal monitored (Normande et al., 2015). Areas with greater concentration of coordinates were classified as fidelity sites (50% kernel; Castelblanco- Martínez et al., 2012); the number of coordinates that com- prised these sites was 50% of all locations recorded for each manatee (Normande et al., 2015).
Assessment of adaptation of released manatees
We evaluated the adaptation of released manatees to the wild considering a number of criteria for success: capacity to find food sources and feed in the short term, remaining in adequate habitat, use of freshwater sources, body mea- surements appropriate for the animal’s age, no evidence of disease or parasites, interaction with native and/or other re- leased manatees, evidence of reproductive behaviour, little
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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