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Bottlenose dolphin photo‐identification data were compiled from western Scotland to identify individuals and ultimately investigate population size, demographic parameters, spatio‐temporal distribution, and movement patterns.Opportunistic citizen science photographs revealed what appeared to be an adult bottlenose × Risso's dolphin hybrid along with an apparent second‐generation hybrid or back‐cross calf. Both had atypically short rostra and the dorsal fin of the adult was noticeably taller than is normal for bottlenose dolphins.Based on these characteristics, this case may represent a congenital rostral abnormality or the first intergeneric calf reported for this species combination, either in captivity or in the wild.The previously reported presence of several putative hybrids and mixed‐species sightings in the area, in combination with the tall dorsal fin, provide support for the second possibility, i.e. intergeneric hybrids.Although rare, hybridization may have disproportionate conservation consequences, with population‐level impacts in very small coastal populations of long‐lived, slow‐breeding animals. [ABSTRACT FROM AUTHOR]

The grouping behaviour of animals is governed by intrinsic and extrinsic factors which play an important role in shaping their social organization. We investigated the influence of ocean climate variation on the grouping behaviour of two widely separated populations of cetaceans, inhabiting north Atlantic and north Pacific coastal waters. The group size of both bottlenose dolphins in the Moray Firth, UK, and killer whales in Johnstone Strait, Canada, varied from year to year in relation to large-scale ocean climate variation. Local indices of prey abundance were also related both to climate indices and predator group sizes. The cetaceans tended to live in smaller groups when there was less salmon available in both areas which seem to occur 2 years after a lower phase of the North Atlantic and Pacific Decadal Oscillations. These findings suggest that, even in highly social mammals, climate variation may influence social organization through changes in prey availability. [ABSTRACT FROM AUTHOR]

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Describes the development of a video technique to study the spatial distribution and relative abundance of bottlenosed dolphins. Features of the technique; Relationship between topography and the distribution of dolphins.

We conducted a mark-recapture survey of bottlenose dolphins Tursiops truncatus in the bays, sounds, and estuaries of North Carolina during July 2000, using photographic identification techniques. During this survey we took 7,682 photographs of dolphins and, of these, 3,457 images were of sufficient quality for analysis. We identified 306 dolphins from distinctive nicks and notches on their dorsal fins. Eighty-six dolphins were photographed on more than one occasion during the course of the survey; one dolphin was photographed on four separate days. We then applied the results of our photographic analyses to several mark-recapture models and examined potential violations of the assumptions of these models, including an unexpected correlation between photo quality and mark distinctiveness. Our analysis suggests that our results are robust to possible violations of these assumptions. The resulting estimates were then scaled to account for the proportion (0.46) of unmarked dolphins in the population. Our best estimate of the number of dolphins present in the inshore waters of North Carolina during July 2000 is 1,033 with a 95% Confidence Interval of 860-1,266 (CV = 0.099). Most dolphins were found in the northern part of the study area, which includes the second largest estuarine system in the United States. [ABSTRACT FROM AUTHOR]