Short-finned pilot whales (Globicephala macrorhynchus) are the most frequently sighted odontocete in a long-term study in Hawaiʹi (representing 23.8% of all odontocete sightings from directed research efforts), yet little has been published on this species in Hawaiian waters. Studies elsewhere have suggested that short-finned pilot whales travel in stable mixed-sex groups composed of strongly associated individuals; however temporal analyses of social structure are lacking. To examine site fidelity, association patterns and temporal relationships, I analyzed data from 267 directed research and opportunistic encounters of short-finned pilot whales off the island of Hawai`i from 2003 through 2007. Sightings occurred year-round. Analysis of sighting depths in relation to effort indicated short-finned pilot whales are strongly associated with the island slope, with no sightings in water >2,700m deep despite effort to ~5,000m. Using only good quality photos, I identified 448 distinctive individuals; of these, 305 (68.1%) were seen more than once and 250 (55.8%) were seen in >1 year. Sighting histories varied from 1-29 sightings per individual (median=3) over the course of the study, suggesting only some individuals exhibit high site-fidelity. Degree of residency was assessed using multi-year site fidelity to the study area; individuals seen ≥5 times in ≥3 years were considered core residents (154 individuals) while individuals who fell below these criteria but that were seen more than once were termed residents (150 individuals) and those seen on a single occasion were termed visitors (142 individuals). Only 71.9% of the whales were linked by association into a single social network, suggesting the possibility of multiple populations using the study area. Individuals demonstrated preferential associations and community division was strongly supported by average-linkage hierarchical cluster analysis of the association data. Nine longitudinally-stable social units composed of key individuals (seen together ≥8 times in ≥4 years) and their constant companions (seen together ≥5 times in ≥3 years) were identified (unit membership 5-16, median=10.5; mean unit association index: 0.62-0.90). Qualitative assignment of age and sex classes to unit members indicated some segregation between adult males and female/calf pairs may occur. Temporal analysis using standardized lagged association rates of individuals grouped in the same encounter produced a best-fit model where dyads gradually disassociated over time while individuals grouped in the same day produced a model where dyads remained in association, suggesting companions not documented during an encounter are likely still present in the study area. Differential patterns of residency and site fidelity were unexpected and may be indicative of multiple populations around the main Hawaiian Islands. Additionally, the presence of a core resident population demonstrating strong, long-term site-fidelity and associations off the island of Hawaiʹi may warrant special management considerations. Evidence of fisheries-related injuries in addition to anthropogenic threats such as high levels of commercial and recreational vessel traffic, targeted tourist activities, and commercial and sports troll fisheries indicate that additional research is needed to evaluate potential threats to this island-associated population.

Made available in DSpace on 2014-12-17T15:37:22Z (GMT). No. of bitstreams: 1 SandraMAA.pdf: 1203751 bytes, checksum: dde7c569f3d043e9bcc9909cdb14baec (MD5) Previous issue date: 2006-10-30 / The behavioral patterns follow to environmental changes, including area fidelity and individuals association patterns. Several techniques are used to record these behavioral patterns and the photo-identification has been suggested as a proper tool because of its various advantages. Based on this technique, this research verified, between August of 2005 and January of 2006, area fidelity and association patterns of Sotalia guianensis, at Distrito de Pipa s bays, Rio Grande do Norte State south coast. Besides, we measured the association patterns by using the Jaccard index or Half-Weight Index (HWI). According the observation, 22 individuals were not resighted, 11 were resighted, and 36 new individuals were recorded. Nowadays, 69 individuals are cataloged. The residency rate indicated heterogeneity on studied area permanence and the association patterns between photo-identified seem to be context-specific. In addiction, the comparison of associations between two different age classes showed some individuals more frequently interacting with immature individuals. We also observed fluidity on association patterns among our individuals. We suggest that S. guianensis population from Pipa shows plasticity / Os padr?es comportamentais acompanham as mudan?as ambientais, incluindo fidelidade ? ?rea e associa??o entre indiv?duos. Dentre as diversas t?cnicas utilizadas para o registro desses padr?es comportamentais, a foto-identifica??o tem sido sugerida como ferramenta adequada por apresentar in?meras vantagens. Baseada nessa t?cnica, esta pesquisa verificou, entre agosto de 2005 e janeiro de 2006, fidelidade ? ?rea e padr?es de associa??o utilizados por indiv?duos da esp?cie Sotalia guianensis, nas enseadas do Distrito de Pipa, litoral sul do Estado do Rio Grande do Norte. Al?m disso, para mensurar os padr?es de associa??o utilizou-se do ?ndice de similaridade de Jaccard ou Half-Weight Index (HWI). Durante o per?odo de observa??o, 22 indiv?duos n?o foram reavistados, 11 recapturados e 36 novos registros foram obtidos. Atualmente, est?o catalogados 69 indiv?duos. A taxa de resid?ncia apontou heterogeneidade de perman?ncia na ?rea estudada e os padr?es de associa??o entre os indiv?duos foto-identificados parecem ser espec?ficos de determinados contextos comportamentais. Enquanto que a compara??o das associa??es entre as diferentes faixas et?rias mostrou que determinados indiv?duos interagiram em maior freq??ncia com indiv?duos imaturos. Observou-se, ainda, fluidez no padr?o de associa??es entre os indiv?duos amostrados. Sugere-se que a popula??o de S. guianensis que utilizam a regi?o de Pipa apresenta elevada plasticidade