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Residence and site fidelity of Sotalia guianensis in the Caravelas River Estuary, eastern Brazil

Published online by Cambridge University Press:  26 February 2007

Marcos R. Rossi-Santos
Affiliation:
Instituto Baleia Jubarte, Rua Barão do Rio Branco, 26, Caravelas-Bahia, Brazil Pós-Graduação em Zoologia, Universidade Federal do Paraná, Centro Politécnico, Curitiba—Paraná, Brazil
Leonardo L. Wedekin
Affiliation:
Instituto Baleia Jubarte, Rua Barão do Rio Branco, 26, Caravelas-Bahia, Brazil Pós-Graduação em Zoologia, Universidade Federal do Paraná, Centro Politécnico, Curitiba—Paraná, Brazil
Emygdio L.A. Monteiro-Filho
Affiliation:
Pós-Graduação em Zoologia, Universidade Federal do Paraná, Centro Politécnico, Curitiba—Paraná, Brazil Instituto de Pesquisas Cananéia, Rua Tristão Lobo, 199. Centro, Cananéia—São Paulo, Brazil

Abstract

Between April 2002 and April 2005, 210 estuarine dolphin groups were sighted, with 58 animals individually identified. Fifteen dolphins were photo-identified just once, while only two animals were sighted in 15 different months. Some individuals showed long-term residence (more than 3 y). Residence rates showed heterogeneity in the dolphin's permanence of the estuary, with 60% of the individuals with low numbers (<10) and only 7% showing high values for residence (maximum=45.9). Continued resightings of some dolphins support the regular use of the study area by the animals, despite some individuals that, after a long time without resightings were registered again. Individual range analysis showed that dolphins shared the same common area, the Caravelas River Estuary. A marked fluctuation in the number of photo-identified dolphins was observed in the study area, revealed by the high number of individuals with just a few resightings. The majority of the dolphins (60%) present a yearly residence pattern, as observed in other areas, suggesting that a few individuals show high fidelity for the area, while many other dolphins move constantly between different areas for unknown reasons.

Type
Research Article
Copyright
2007 Marine Biological Association of the United Kingdom

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