Percorrer por autor "Raffaelli, Claire"
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- Site fidelity and residency patterns of rough toothed dolphins ( Steno bredanensis ) in Madeira Island, using photo identification dataPublication . Raffaelli, Claire; Marçalo, Ana; Sambolino, AnnalisaThe rough toothed dolphin Steno bredanensis ) is a poorly understood odontocete species with a scattered global distribution, particularly in oceanic and insular habitats. In the Eastern North Atlantic, including the waters surrounding Madeira, their habitat use and movement patterns remain largely unknown. This study presents the first long term assessment of site fidelity and residency of rough toothed dolphins in Madeira using photo identification data . A total of 63 7 distinct individuals were identified during 160 days of sampling occasions between 2016 and 2024 , based on distinctive dorsal fin markings (3 4) and high image quality (2 4)4). Using Lagged Identification Rates, residency modeling, and site fidelity indices, temporal patterns of occurrence and return were analyzed . The discovery curve did not reach an asymptote, and 6 2 5 % of individuals were seen only once, suggesting an open population. The best fit residency model estimated that at any given time, ~28 individuals are present, with an average stay of 6.7 days and absence of ~1700 days, indicating transient usage of the a rea. However, a subset of individuals exhibited recurrent visitation patterns. The c luster analysis of site fidelity indices revealed two distinct patterns: a larger group with intra and interannual fidelity chara cterized by short term, periodic visits; and a smaller group with inter annual fidelity and longer presence spans. These findings point to ecological heterogeneity within the population, potentially driven by individual preferences, social structure, or en vironmental factors. Despite these variations, the overall metrics point to a limited and discontinuous use of the region. In conclusion, rough toothed dolphins show generally low site fidelity to Madeira, as evidenced by short residence durations, long ab sences, and low re sighting rates. These results align with their presumed ecological preference for wide ranging movements in oceanic habitats. Understanding this spatio temporal variability is crucial to inform conservation efforts, particularly in dynam ic and low density contexts typical of pelagic cetaceans.