[MARMAM] social organization of marine tucuxi dolphins

Marcos Santos sotalia at gmail.com
Wed Apr 30 05:25:08 PDT 2008

Dear Marmamers:

The following manuscript was recently published. The pdf file is available
on request to sotalia at gmail.com
Marcos C.

Santos, M.C. de O. and Rosso, S. 2008. Social organization of marine tucuxi
dolphins, Sotalia guianensis, in he Cananéia estuary of southeastern Brazil.
Journal of Mammalogy, 89(2):347-355.

Abstract: Social organization is an important component of the population
biology of a species that influences gene flow, the spatial pattern and
scale of movements, and the effects of predation or exploitation by humans.
An important element of social structure in mammals is group fidelity, which
can be quantified through association indices. To describe the social
organization of marine tucuxi dolphins (Sotalia guianensis) found in the
Cananéia estuary, southeastern Brazil, association indices were applied to
photo-ID data to characterize the temporal stability of relationships among
members of this population. Eighty-seven days of fieldwork were conducted
from May 2000 to July 2003, resulting in direct observations of 374 distinct
groups. A total of 138 dolphins were identified on 1-38 distinct field days.
Lone dolphins were rarely seen, while groups were composed of up to 60
individuals (mean + 1SD  = 12.4 ± 11.4 individuals per group). A total of
29,327 photographs were analyzed, of which 6,312 (21.5%) were considered
useful for identifying individuals. Half-weight (HW) and simple ratio (SR)
indices were used to investigate associations among S. guianensis as
revealed by the entire dataset, data from the core study site, and data from
groups composed of < 10 individuals. Monte Carlo methods indicated that only
3 (9.3%) of 32 association matrices differed significantly from expectations
based on random association. Thus, our study suggests that stable
associations are not characteristic of S. guianensis in the Cananéia

Dr Marcos César de Oliveira Santos
Projeto Atlantis, Laboratório de Biologia da Conservação de Cetáceos
Departamento de Zoologia, Instituto de Biociências,
Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP), Campus Rio
Av 24-A, 1515, Bela Vista, Rio Claro, SP, Brasil, 13506-900.
Telefone/Phone: 55-19-3526-4294
Fax: 55-19-3526-4300
E-mail: sotalia at gmail.com

Endereço Residencial/Home Address:
Avenida 8, Número 1837, Apto 63
Jardim Claret, Rio Claro, SP, Brasil
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