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(1) Radio-telemetry was used to study common seal activity patterns around Orkney, and to assess the degree of individual, seasonal and sex-related variation in haul-out behaviour in 1984-86. (2) During the summer, both males and females hauled-out regularly, in a marked diurnal pattern, but there were differences in other aspects of their haul-out behaviour. (3) Males showed a marked change in their haul-out behaviour at the beginning of moult. At this time, they hauled-out every day and, consequently, male behaviour became more synchronous. The change in behaviour of the male followed in 1985 was closely related to changes in abundance at the haul-out site that he used over this period (4) In contrast, females showed no sign of a similar change in behaviour at the beginning of moult, but appeared to spend more of their time at sea after lactation. (5) During the winter, seals appeared to spend more time in offshore waters, although they regularly returned to the inshore study area to haul-out. At this time of year there was no marked diurnal haul-out pattern. (6) There was a high degree of individual variation in the effect of the tidal cycle on activity patterns, which appeared to be related to tide-related changes in food and habitat availability. Overall, however, the tidal cycle had less effect on haul-out behaviour in summer, when strong circadian patterns were more important. (7) The variations in activity patterns found in this study are discussed in relation to seasonal changes in feeding activity and the demands of breeding and moult. [ABSTRACT FROM AUTHOR]

This study investigated the distribution of a population of bottlenose dolphins Tursiops truncatus resident in the Moray Firth off north-eastern Scotland. Results add to existing information from studies in tropical areas to provide a better understanding of area use in this species. Boat-based surveys and photo-identification techniques were used to study the distribution and movements of individually recognizable dolphins over a 3-year per-Dolphins were seen in all months of the year, but there were consistent seasonal fluctuations in the number of individuals present. Numbers were low in winter and spring and peaked in summer and autumn. Dolphins were seen throughout the survey area but were concentrated in three regions. Each had similar topographic features being centred on deep, narrow channels subject to strong tidal flows. Area use by dolphins changed with season. The outer part of the inner Moray Firth study area was used for most of the year and areas closer to the head of the firth were used seasonally. The summer increase in numbers of dolphins in the inner Moray Firth was not simply due to incomers diluting an already resident population. Instead, there was a stratified movement of all individuals. This persistent geographical stratification suggests that competition between individuals or social groupings may shape spatial distribution in this population. Individuals exhibited rapid movements across the population‘s range. For instance, one individual was sighted at locations 190 km apart within a 5-day period. In terms of conservation, the high use of areas at the mouths of the inner firths warrants special attention. Furthermore, the stratification patterns amongst dolphins suggest that individuals do not move freely within the inner Moray Firth and therefore may be unable to move away from localized disturbance or pollution. [ABSTRACT FROM AUTHOR]