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In dynamic fission-fusion societies, following specific individuals consistently would not be expected in the absence of benefits to followers. Followers in groups may benefit if leaders have greater knowledge about habitats that are available for foraging and how to access these areas efficiently. A small residential population of bottlenose dolphins (Tursiops truncatus) in the Lower Florida Keys (LFK) demonstrates such specific individual leadership, but why others choose to follow is unknown. To determine whether consistent leaders demonstrated greater knowledge of resources and habitat we (1) compared habitat use patterns across areas that varied in prey abundance for groups led by consistent leaders and groups led by individuals that did not consistently lead, (2) compared directness of travel along with number of lead animal switches when traveling for these same two group types and (3) compared home range size and home range complexity between animals that consistently led and those that did not. Foraging groups led by consistent leaders were sighted more frequently over habitat with higher fish biomass, while those led by non-consistent leaders were sighted most often over habitat with lower fish biomass. Groups with consistent leaders had less frequent lead animal switches and took more direct paths when traveling than groups led by those that did not consistently lead. Home ranges of consistent leaders did not differ in size from other individuals, but were more complex. Our results indicate that followers in LFK dolphin groups could potentially benefit from those that consistently lead due to use of profitable habitat, ability to navigate efficiently and potentially the number of areas consistent leaders are familiar with. [ABSTRACT FROM AUTHOR]

Foraging animals must often balance the conflicting demands of finding food and avoiding predators. Temporal variation in predation risk is expected to influence how animals allocate time to these behaviours. Counterintuitively, the proportion of time spent foraging during both high- and low-risk periods should increase with increasing time exposed to high risk. We tested this prediction using intertidal marine snails (Littorina spp.) that were exposed to temporal variation in perceived predation risk from crabs (Cancer productus and Cancer magister). Our results were consistent with those predicted for high-risk, but not low-risk, periods. During high-risk periods, a greater number of snails foraged (versus those that left the water or remained in their shells) as time at high perceived risk increased. For low-risk periods, there was no relationship between the number of snails foraging and time at high risk. This might be due to snails in all treatments foraging maximally in the low-risk periods. As a consequence, the difference in the number of snails foraging between high- and low-risk periods decreased with increasing time subject to high risk. These results indicate that the commonly used protocol of exposing foragers to a single pulse of heightened risk might tend to overestimate their typical investment in anti-predator behaviour.

Large brain size in mammals has been related to the number and complexity of social relationships, particularly social alliances within groups. The largest within-group male alliance known outside of humans is found in a social network (> 400) of Indian Ocean bottlenose dolphins (Tursiops aduncus) in Shark Bay Western Australia. Members of this dolphin 'super-alliance' cooperate against other alliances over access to females. Males within the super-alliance form temporary trios and occasionally pairs in order to consort with individual females. The frequent switching of alliance partners suggests that social relationships among males within the super-alliance might be relatively simple and based on an equivalence rule', thereby allowing dolphins to form large alliances without taxing their 'social intelligence'. The equivalence model predicts that the 14 males in the super-alliance should not exhibit differences in alliance stability or partner preferences. However, data from 100 consortships do not support the equivalence hypothesis. The 14 males exhibited striking differences in alliance stability and partner preferences suggesting that the super-alliance has a complex internal structure. Further, within the super-alliance, alliance stability correlates with consortship rate, suggesting that differentiated relationships within the super-alliance are based on competition for access to females.