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Female Dolphins (female + dolphin)
Selected AbstractsA Sex-Specific Affiliative Contact Behavior in Indian Ocean Bottlenose Dolphins, Tursiops sp.ETHOLOGY, Issue 7 2006Richard Connor A variety of signals are employed by animals to establish, mediate and advertise social bonds. Gentle contact behaviors, such as grooming in primates, are an important class of affiliative signals that may provide direct benefits (e.g. stress reduction, parasite removal) in addition to their signal information. Unlike other kinds of signals (e.g. male displays) examples of affiliative contact behaviors restricted to one sex are rare. Here we describe a strongly sex-biased affiliative behavior ,contact swimming', in female bottlenose dolphins in Shark Bay, Western Australia. Females were more likely to be observed contact swimming than males and the presence of males likely influenced this behavior. This is surprising given that female relationships have been characterized as weak. Female dolphins are sometimes herded and harassed by males and contact swimming occurs most often between females in male-biased groups. Contact swimming may serve as a signal of cooperation between females. Possible direct benefits include stress reduction and assisted locomotion. [source] Morphometry and sexual dimorphism of the coastal spotted dolphin, Stenella attenuata graffmani, from Bahía de Banderas, MexicoACTA ZOOLOGICA, Issue 4 2004Laura Sanvicente-Añorve Abstract External measurements and size differences between the sexes were examined in the coastal spotted dolphin, Stenella attenuata graffmani, in Bahía de Banderas, on the Mexican Pacific coast. The dolphins were collected by local fishermen and 29 external characteristics were measured by members of the Marine Mammals Laboratory, University of Mexico. The length of each characteristic with respect to total length was analysed through adjustment of the data to a power equation. A stepwise discriminant analysis was applied to the absolute values and to those expressed as proportions to analyse the differences between the sexes. Results indicate that growth in these dolphins is generally negatively allometric, and most of the characteristics measured were, in both absolute and proportional terms, greater in male dolphins than in female dolphins. As found in many species of odontocetes, the discriminant analysis showed that the main differences between the sexes for this coastal subspecies include the relative positions of the umbilicus, the genital aperture and the anus. The morphometric data provided by this study, corresponding to 29 specimens of S. a. graffmani collected in a restricted locality of the Mexican Pacific coast, are particularly interesting to studies documenting latitudinal morphological differences in the coastal spotted dolphin. [source] Probabilistic risk assessment of reproductive effects of polychlorinated biphenyls on bottlenose dolphins (Tursiops truncatus) from the Southeast United States coastENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2002Lori H. Schwacke Abstract High levels of polychlorinated biphenyls (PCBs) have been reported in the tissues of some species of marine mammals. The high concentrations are of concern because a growing body of experimental evidence links PCBs to deleterious effects on reproduction, endocrine homeostasis, and immune system function. Much of the recent research has focused on determining the exposure of marine mammal populations to PCBs, but very little effort has been devoted to the actual risk assessments that are needed to determine the expected impacts of the documented exposures. We describe a novel risk assessment approach that integrates measured tissue concentrations of PCBs with a surrogate dose-response relationship and leads to predictions of health risks for marine mammals as well as to the uncertainties associated with these predictions. Specifically, we use PCB tissue residue data from three populations of bottlenose dolphins (Tursiops truncatus), study the feasibility of published dose-response data from a surrogate species, and combine this information to estimate the risk of detrimental reproductive effects in female dolphins. Our risk analyses for dolphin populations near Beaufort (NC, USA), Sarasota (FL, USA), and Matagorda Bay (TX, USA) indicate a high likelihood that reproductive success, primarily in primiparous females, is being severely impaired by chronic exposure to PCBs. Excess risk of reproductive failure, measured in terms of stillbirth or neonatal mortality, for primiparous females was estimated as 60% (Beaufort), 79% (Sarasota), and 78% (Matagorda Bay). Females of higher parity, which have previously off-loaded a majority of their PCB burden, exhibit a much lower risk. [source] BUBBLESTREAM WHISTLES ARE NOT REPRESENTATIVE OF A BOTTLENOSE DOLPHIN'S VOCAL REPERTOIREMARINE MAMMAL SCIENCE, Issue 1 2005Deborah Fripp Abstract Whistling bottlenose dolphins sometimes identify themselves with a concurrent bubblestream, and some researchers use these bubblestream whistles as their sole whistle sample. However, bubblestream whistles are not known to be representative of the entire repertoire. Bubblestreams and whistles were recorded from three captive female dolphins and their newborn calves. Bubblestreams were rare (0.13/min), with calves producing ten times as many as adults. Overall, 79% of bubblestreams were associated with whistles, but only 1 % of whistles were associated with bubblestreams. Bubblestream whistles were not independent: 49% occurred within 1 sec of another bubblestream, and 72% of these had the same contour as other bubblestream whistles in the bout. Bubblestream use was context-dependent: adults were more likely to bubblestream when caring for a calf (P < 0.001), and calves were more likely to bubblestream when other calves were present (P < 0.001). Bubblestreams were not associated with all whistle types. Bubblestream whistles were not evenly distributed across the clusters of a hierarchical cluster analysis of contour parameters using 300 randomly selected non-bubblestream whistles and 92 independent bubblestream whistles (10 clusters, P= 0.003). In conclusion, bubblestreams are rare visual cues that dolphins produce in association with certain whistles in certain contexts and are not representative of the dolphin's repertoire. [source] POPULATION STRUCTURE IN AN INSHORE CETACEAN REVEALED BY MICROSATELLITE AND mtDNA ANALYSIS: BOTTLENOSE DOLPHINS (TURSIOPS SP.) IN SHARK BAY, WESTERN AUSTRALIAMARINE MAMMAL SCIENCE, Issue 1 2004Michael Krützen Abstract We examined population substructure of bottlenose dolphins (Tursiops sp). in Shark Bay, Western Australia, using 10 highly polymorphic microsatellite loci, and mitochondrial DNA (mtDNA). For microsatellite analysis, 302 different animals were sampled from seven localities throughout the bay. Analysis of genetic differentiation between sampling localities showed a significant correlation between the number of migrants (Nm) calculated from FST, RST and private alleles, and distance between localities,a pattern of isolation-by-distance. For mtDNA, 220 individuals from all seven localities were sequenced for a 351 base pair fragment of the control region, resulting in eight haplotypes, with two distinct clusters of haplotypes. Values of FST and (,)ST for mtDNA yielded statistically significant differences, mostly between localities that were not adjacent to each other, suggesting female gene flow over a scale larger than the sampled localities. We also observed a significant correlation between the number of female migrants calculated from FST and ,ST and the distance of sampling localities. Our results indicate that dispersal in female dolphins in Shark Bay is more restricted than that of males. [source] | ||||||||||