Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 115-117). Also available via the Internet.

Bottlenose dolphins (Tursiops truncatus) produce a wide variety of sounds but little is known about the function and organization of their vocal repertoires. This thesis investigates several aspects of call usage and compares the biological validity of classification methods for dolphin whistles. Passive acoustic localisation methods were used to identify which animal produced a sound. Observations of captive dolphins in the Zoo Duisburg, Germany, showed that signature whistles are almost only used when the group was split up, but not if all animals swam in together in the same pool. This finding supported the hypothesis that signature whistles are cohesion calls. Whistles from these observations were used to compare whistle classification conducted by eye with three computer methods using different similarity measures. Only the human observer classification was able to recognize whistle types that were used in a context- specific way by the animals confirming the power of this common classification method. Copying of signature whistles and whistle matching between animals was rare in captivity. However, observations of whistle interactions in the Moray Firth, Scotland, showed that wild dolphins do not tend to interact vocally in general, but that whistle matching was more frequent than expected by chance. Whistle matching in captivity was rare. Sound pressure measurements of dolphin whistles in the wild showed that source levels can reach up to 169 dB re 1 ?Pa and that the active space of a dolphin whistle can range up to 38 km. Finally, observations of foraging in wild dolphins revealed that they produce low frequency braying sounds in this context. Other dolphins would rapidly approach the caller in response to a bray. However, it is not clear whether brays function to attract conspecifics or manipulate prey behaviour.

Thesis (M.S.)--University of North Carolina at Wilmington, 2004. / Includes bibliographical references.

Thesis (Ph.D.)--Murdoch University, 2005. / Thesis submitted to the Division of Science and Engineering. Includes bibliography.

Thesis (Ph.D.)--Murdoch University, 2005. / Thesis submitted to the Division of Science and Engineering. Bibliography: leaves [168-198].

Thesis (M.S.)--University of North Carolina at Wilmington, 2005. / Includes bibliographical references (leaves: 65-59)

Long-term individual-based studies can be central to collecting data on aspects of individual and population biology and ecology. Photo-identification often underpins longterm individual based studies, particularly for cetaceans. Bottlenose dolphins (Tursiops truncatus) are long-lived with low reproductive rates and complex social structures, while showing plasticity in their behaviour, biology and ecology. As such long-term individual based studies are key to investigating the complexities of their population dynamics. My aim for this thesis was to synthesise over two decades of photo-identification data with the intention of exploring the value and contribution of a long-term individual based photo-identification study and answer key questions about the ecology and biology of bottlenose dolphins in Scottish waters. This thesis provides the first data on distribution and status of bottlenose dolphins around Scotland. Results highlighted the smaller population on the west coast split into two discrete communities with different ranging patterns and provided the first evidence that the highly mobile east coast population may be increasing. For the east coast of Scotland bottlenose dolphin population, laser photogrammetry identified morphological differences (larger size, no sexual dimorphism, no sex differences in growth) and highlighted fitness consequences to variation in early calf growth (calves that died over their first winter were significantly shorter). This thesis also identified differences in social structure over two decades at the two extremes of the population's range, potentially caused by or a consequence of, range expansion. Finally, this study provided empirical evidence of increasing trends in population abundance, reproductive rate and calf survival. This is a rare example of empirical evidence of a positive trend in demographic parameters of a cetacean population using a marine protected area. This work highlights the need for long-term individual based data to detect biologically meaningful change and suggests this small bottlenose dolphin population is a conservation success story.

Knowledge of the structuring of natural populations is important for understanding both evolutionary processes and population ecology, and for supporting management decisions. Conventional methods of direct observation often suffer from a lack of resolution, particularly when studying mobile animals in a marine environment. In this study, I combined direct observation with indirect molecular genetic approaches to infer the social and population structure of coastal (inshore) bottlenose dolphins, Tursiops truncatus. Genetic diversity and structure of bottlenose dolphins around the UK and Ireland was examined using tissue samples from stranded dolphins and incidental fisheries by-catch. Mitochondrial DNA (mtDNA) sequence data indicated significant subdivision among four main sample regions (NE Scotland, Wales, NW Scotland and Ireland). Genetic divergence between NE and NW Scotland populations, and low genetic diversity within the NE Scotland population, provide further support for the precautionary approach currently applied to the management of this population. Inference from both mtDNA and nuclear microsatellite genetic markers, and direct observational data were used to examine the social and population structure of bottlenose dolphins in the NE Bahamas. Novel strategies for collecting genetic samples (remote biopsy and faecal sampling) from free-ranging dolphins were developed and validated, enabling an individual-based analysis of population subdivision. Patterns of individual associations in two contrasting habitats indicated that environmental pressures affect dolphin grouping patterns; with a genetic basis for social affiliations occurring only where predation pressures are low. Nonetheless, a particularly notable feature of the social structure in both habitats was the persistence of stable alliances among maternally related males. At the population level, the significant degree of genetic structuring revealed among three sampled regions on Little Bahama Bank, supported the high degree of site fidelity suggested by individual-based photo-identification data. Contrary to the patterns of male dispersal and female philopatry common among both mammals and bottlenose dolphins, sex-specific patterns of genetic differentiation inferred from both mtDNA and microsatellite markers were indicative of female-mediated gene flow. This study provides novel insight into the factors governing the patterns of structuring within populations of highly mobile small cetaceans, and demonstrates the value of integrating both direct (field-based) and indirect (molecular genetic) data in the study of free-ranging animals.

No description available.

Thesis (M.S.)--University of North Carolina Wilmington, 2007. / Includes bibliographical references (leaves: 64-66)