Abstract: In groups of ten, indidual starlings, Sturnus vulgaris, spent significantly less time in surveillance than did individuals in smaller groups and responded more quickly than single birds to a flying model hawk. Captive starlings in flocks reduce their individual surveillance efforts, but their combined efforts still enable them to be more effective than single birds in the detection of predators. Foraging behaviour of flocks was observed by placing single starlings with groups of tricoloured blackbirds, Agelaius tricolor; the starlings reduced the time they devoted to surveillance at the same rate as if they were with other starlings.

Abstract: When novel behaviour patterns spread through animal populations, typically one animal will initiate the diffusion. It is not known whether such 'innovators' are particularly creative individuals, individuals exposed to the appropriate environmental contingencies, or individuals in a particular motivational state. We describe three experiments that investigated the factors influencing foraging innovation in the guppy Poecilia reticulata. We exposed small laboratory populations of fish to novel foraging tasks, which involved exploration and problem solving to locate a novel food source. Experiments 1 and 2 found that (1) females were more likely to innovate than males, (2) food-deprived fish were more likely to innovate than nonfood-deprived subjects, and (3) smaller fish were more likely to innovate than larger fish. We suggest that the sex difference may reflect parental investment asymmetries in males and females. Experiment 3 found that past innovators were more likely to innovate than past noninnovators. Collectively, the results suggest that differences in foraging innovation in guppies are best accounted for by differences in motivational state, but, in addition, guppies may vary in their predisposition to innovate. Copyright 1999 The Association for the Study of Animal Behaviour.

Abstract: The arrangement of a social group of individuals into a dominance hierarchy is useful in studies of social behaviour only if a wide variety of social interactions can then be predicted. However, definitions of dominance commonly used are numerous and confused. To assess the usefulness of the concept of dominance, studies were made on six breeding groups of rhesus macaques (Macaca mulata) to determine whether different measures of dominance agreed with each other. The measures tested in this study were found to agree. It is therefore suggested that dominance is a useful intervening variable. Possible reasons for the reported lack of correlation between some measures used by other authors are discussed.

Abstract: Summary Three groups of eight female golden hamsters without prior breeding experience were presented with three newborn pups for a 15 min test period. Group V were virgin females, group P pregnant females and group L lactating females. Groups P and L were tested within 24 hr of parturition. Group V attacked and killed all pups presented. Group P showed maternal responses after initial attacks while group L accepted the pups. Groups P and L did not differ significantly on measures of maternal responsiveness but all three groups differed significantly from one another on measures of attacking behaviour and the eating of young.

Abstract: During the pre-maturation period crowded males of Schistocerca gregaria are more active than isolated ones but the greater part of their extra activity is not locomotory but consists of the kicking movements made in response to contact with other locusts. Isolated males walk less often during this period but tend to jump (or fly) more than crowded ones. Activity increases with maturity and the increase is greater in the isolated males so that in spite of the absence of mechanical stimulation by other locusts their locomotor activity is now at least as great as that of the crowded ones and their jumping activity greater. Within one batch there is a tendency for those males which are most active during the first two weeks of adult life to mature earliest. The activity of young males crowded with fledglings is at first similar to that of males crowded with older locusts, but after the first two weeks the activity of both mature and immature males is depressed by crowding with fledglings. Mature males habitually isolated become less active when temporarily crowded with fledglings, but not when crowded with mature males. Mature and immature males habitually crowded with fledglings become more active when temporarily isolated and still more active when crowded with each other, or with other mature males. The inhibiting effect of the fledglings on maturation and their depressive effect on activity should in natural conditions promote synchronization of maturation and the cohesion of the group. There was little difference in activity between young males kept in single pairs and in isolation, except that in one experiment the isolated ones jumped more often. Young males kept in pairs with mature males are more active during the first week of adult life than those kept in pairs with each other. The males paired with mature males were also seen feeding much less often than those paired with each other. This was the only treatment in which a significant effect on the frequency of feeding was recorded. The femoral vibrations made by both mature and immature males in response to stimulation by mature males, occur less often in habitually crowded males than in those temporarily crowded or kept with one mature male only. This is presumably the result of habituation to the stimulus. The behaviour of wild Schistocerca males in a large outdoor cage was very similar to that of a low density laboratory group. All results suggest that there is an association between high activity and rapid maturation. This is compatible with the conclusion from earlier work that a low level of feeding is associated with rapid maturation.