Azevedo, José Manuel Viegas de Oliveira NetoHoelzel, A. RusHartman, Karin Louise2017-04-072017-04-072015-06-01Hartman, Karin Louise. "Patterns of social ecology of Risso's dolphins (Grampus griseus) off Pico Island, Azores". 2015. 171 p.. (Tese de Doutoramento em Biologia). Ponta Delgada: Universidade dos Açores, 2014. [Consult. Dia Mês Ano]. Disponível em www:<http://hdl.handle.net/10400.3/4074>.http://hdl.handle.net/10400.3/4074Tese de Doutoramento, Biologia, 1 de junho de 2015, Universidade dos Açores.This PhD thesis is focusing on the ecology of a medium sized and poorly studied oceanic dolphin species: The Risso’s dolphin (Grampus griseus). […]. In this study, we present for the first time a model for the social structure of Risso’s dolphin (Grampus griseus Cuvier 1812). Over the period 2004-2006, 1028 Risso’s dolphins were identified at Pico Island, Azores. Individuals sighted on 10 or more occasions were included in analysis of social structure (n = 183). High resighting rates indicate strong site-fidelity of at least part of the population. We found that individuals form stable long-term bonds, organised in pairs, or in clusters of 3-12 individuals. Social structure is stratified based on age and sex classes, with strong associations between adult males and adult females. We suggest that clusters form the basic units of Risso’s dolphin society. Thirteen pods consisting solely of adults, likely males, and 3 pods consisting of mother-calf pairs were identified. Males are organised in stable, long-term associations of varying size that occur throughout the complete range of behavioural states observed. For females, associations can be of similar strength, but the time-scale may vary depending on the presence of nursing calves. As subadults, associations also occur (pair-formation), but are less stable than those observed for adults. We propose a new model for Risso’s dolphin societies known as a stratified social organisation, which differs from the fission-fusion and matrilineal society models. […].engBiologia MarinhaEcologia MarinhaGolfinho de RissoEcologia Social (Animal)Ilha do PicoAçores(Grampus griseus)Dolphin SocietyRisso's Dolphindoctoral thesis101545576