Comportamento social de botos-cinza, sotalia guianensis, na praia de Pipa, RN, Brasil: dinâmica, sequência, sincronia e respostas ao turismo de observação
Social behavior of Guiana dolphins, Sotalia guianensis, at Pipa Beach, RN, Brazil: dynamics, sequence, breathing synchrony, and responses to dolphin watching. Social animals form groups that can range from temporary to permanent. Depending on the nature of the social relationships developed betwe...
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| Formato: | Dissertação |
| Idioma: | por |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/17312 |
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| Resumo: | Social behavior of Guiana dolphins, Sotalia guianensis, at Pipa Beach, RN, Brazil:
dynamics, sequence, breathing synchrony, and responses to dolphin watching.
Social animals form groups that can range from temporary to permanent. Depending on
the nature of the social relationships developed between individuals, groups present a
particular social organization and the effect of these interactions shapes the activity
patterns of these animals. This study investigates: (i) fission-fusion dynamics of Guiana
dolphins, through the analysis of three dimensions of the social system (variation in
spatial cohesion, variation in size and composition of groups), (ii) sequence, routine and
behavioral stability, (iii) breathing intervals in synchronized groups and (iv) behavioral
responses of the animals to dolphin watching. Systematic observations of Guiana
dolphins were made from a platform located in cliffs about 25 m above sea level that
surround Madeiro Bay, Pipa Beach. Sampling occurred from December 2007 to
February 2009 between 0600 h and 1600 h, and the groups of Guiana dolphins were
investigated according to their size (alone and group) and composition (adults, adults
and juveniles, and adults and calves). According to the analysis of fission-fusion
dynamics, Guiana dolphin groups frequently changed their composition, modifying
their patterns of spatial grouping and cohesion every 20 minutes on average. More than
50% of the individuals maintained a distance of up to 2 m from other group members
and new individuals were attracted to the group, especially during feeding, leaving it for
foraging. Large groups were more unstable than small, while groups containing only
adults were more stable than groups of adults and juveniles. According to the Z-score
analysis to investigate the sequence and behavioral routine, lone individuals were more
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involved in foraging and feeding, while resting was more common in groups. Foraging
and feeding were more common in homogeneous groups (individuals of the same age
class), while heterogeneous groups (different age classes) were often involved in
socialization, displaying a broader behavioral repertoire. Foraging and resting behavior
presented higher stability (continuous duration in minutes) than the other behaviors. The
analysis of breathing intervals in synchronized groups showed significant differences
depending on type of behavior, composition and area preference. During resting,
breathing intervals were of longer duration, and groups with calves showed shorter
breathing intervals than groups without calves. Lone individuals also preferred areas
called corral , often used for the entrapment of fishes. The Markov chain analysis
revealed behavioral changes in the presence of boats, according to the type of group
composition. Groups composed of adults presented decreased resting and increased in
traveling during the presence of boats. Groups of adults and juveniles showed a massive
reduction of socialization, while the behavior transition probability traveling-traveling
was higher in groups of adults and calves. In the presence of the boats, stability of
resting was reduced by one third of its original duration and traveling more than
doubled. The behavioral patterns analyzed are discussed in light of socio-ecological
models concerning costs and benefits of proximity between individuals and behavioral
optimization. Furthermore, significant changes in behavioral patterns indicate that
Guiana dolphins, at Pipa Beach, have suffered the effects of tourism as a result of
violation of rules of conduct established for the study area |
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