Basking sharks Cetorhinus maximus tend to aggregate in summer at favoured locations along Britain and Ireland's west coast. Sharks have been described approaching and close-following one another, often to one side. This has been interpreted as putative pre-mating behaviour. At aggregation sites around the Inner Hebrides we used boat-based observation and in-water and overhead drone video-photography to document behaviour and to determine the sex of individuals. It was confirmed that a shark will frequently move purposely towards another from a distance and swim to maintain a position either directly behind or closely to one side of a conspecific for short periods. Contrary to expectation, we found no relationship between the sex of a shark or its size and close-following. This suggests that following behaviours are not mainly related to courtship. Further, abrasions on the nose suspected to be related to male behaviour were found to occur on both sexes, although abrasions on pectoral fins, similarly suggestive of mating-related behaviour, were predominantly on females. Breaching by basking sharks has also been proposed as a means of attracting the opposite sex. We observed breaching by solitary sharks but commonly by sharks within aggregations, and at other times by more than one shark on the same day at the same time; but there was not any clear evidence to indicate that breaching is primarily related to mating. More likely individuals show close following chiefly for feeding-related hydrodynamic advantage. It remains plausible however that mature sharks make use of feeding aggregations to initiate pre-courtship behaviour.

The behavioural use of rock crevices by rock hyrax Procavia capensis was essential in avoiding harsh environmental conditions during summer. Foraging was the most dominant above-ground behaviour exhibited by rock hyrax during summer. Most ambient temperatures in the early morning of summer fell within the rock hyrax thermoneutral zone, which enabled the animals to forage without the need for prior heating from a solar energy source. Basking was an essential behaviour displayed by rock hyrax in winter. The low quality and scarce food source may be inadequate to meet the metabolic requirements of rock hyrax at low ambient temperatures. It therefore seems that basking is not only an energy conservation mechanism but also essential for the survival of rock hyrax during winter. Juvenile rock hyrax have a higher surface area to volume ratio and are more vulnerable to low ambient conditions than adults. As a result they displayed a different behaviour pattern to adult rock hyrax during winter. Juveniles required larger amounts of food to meet their energetic requirements, while adults spent greater amounts of time basking. The extent to which rock hyrax meet energetic requirements depends on the interaction of ambient temperature, food availability, food quality and foraging efficiency in the presence of predators. The extent to which each of these factors influenced behaviour differed on a daily and seasonal basis.

Geese have to satisfy the high energy demands of flight with a low-energy and bulky food. When feeding on food items that are concentrated and widespread, as is the case in geese, an individual's instantaneous intake rate is largely determined by its bite size. Inter-individual variation in bite size was measured in barnacle geese Branta leucopsis, with the hypotheses that bite size would scale with (sward height)a, where 0<a<1, and (bill length)b, where b=3.0, and that there would be a positive interaction between these explanatory variables. Using a generalized linear mixed modelling analysis, bite size was found not to vary over the measured sward heights, whilst bite size was found to scale with bill length to the power b=14.24 (SE=2.05). There was no significantly detectable interaction between these terms, indicating that barnacle geese with longer bills had larger bite sizes over the full range of sward heights studied. Bill length scaled with body mass to the power 0.21 (SE=0.01). Combining this with the scaling of bite size to bill length, we conclude that bite size scales with body mass to the power 2.99. Our results suggest that larger barnacle geese have a disproportionately larger bite size than smaller geese, which may explain the fitness advantages of larger geese observed in other studies. However, smaller geese may resist this selection pressure by selectively consuming more nutritious plant parts or altering their bite rates.

When prey availability depends on water depth, a diver should choose an optimal depth for foraging. A model that predicts the optimal foraging depth for a diver is presented in this paper. General predictions derived from the model are: (1) optimal foraging depth is always shallower than the depth at which prey density is the highest, even if the depth of the highest prey density is within easy reach; (2) a larger diver should make deeper and longer dives and stay longer on the surface than smaller divers for optimal foraging; (3) foraging efficiency of larger divers is not always greater than smaller divers, although the larger divers forage at the depth of higher prey density. These predictions, derived from the model, are consistent with the comparative studies of diving behaviour in marine birds.