Occupancy dynamics of South American sea-lions in Brazilian haul-outs.
Along the Brazilian coast only two haul-outs of South American sea lions (Otaria flavescens) are known: Ilha dos Lobos and Molhe Leste, both located in the southernmost state of Brazil, Rio Grande do Sul. Most sea lions observed in these haul-outs are adult and sub-adult males. It is supposed that the species' presence in these areas is due to food supply and absence of parental assistance by males. This study analysed the use of these haul-outs by O. flavescens between 1993 and 2002 based on counting data of observed individuals. Bayesian generalised linear mixed models were used to evaluate differences in abundance between areas, long term trends and seasonal patterns. Results showed that for O. flavescens abundance had a long term trend of increased average occupancy over the study period, with seasonal variation reaching the highest within-year value in August (Ilha dos Lobos) and October (Molhe Leste). The novel application of this powerful statistical modelling approach resulted in a useful tool to quantify occupancy dynamic.
Pós-Graduação Oceanografia Biológica, Instituto de Oceanografia, Universidade Federal do Rio Grande, Rio Grande, RS, Brazil.
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H
Pavanato
Núcleo de Educação e Monitoramento Ambiental, Rio Grande, RS, Brazil.
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KG
Silva
Núcleo de Educação e Monitoramento Ambiental, Rio Grande, RS, Brazil.
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SC
Estima
Núcleo de Educação e Monitoramento Ambiental, Rio Grande, RS, Brazil.
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DS
Monteiro
Grupo de Pesquisa em Estatística Ambiental, Instituto de Matemática, Estatística e Física, Universidade Federal do Rio Grande, Rio Grande, RS, Brazil.
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PG
Kinas
D000818:Animals; D001938:Brazil; D005260:Female; D008297:Male; D011156:Population Density; D011157:Population Dynamics; D046070:Sea Lions / Q000145:classification*