Abstract: Group living can confer advantages to individuals, but it can also impose severe costs through resource competition. Kleptoparasitism is one example in which some individuals (joiners) can exploit the food discovered by other animals (finders). This type of social foraging has been modelled either as an information-sharing model or as a producer-scrounger game. An important variable in these models is the finder's advantage: the number of items obtained by the finder before the arrival of other individuals. In this study we describe how the spatial position and rank of individuals in a group of wild tufted capuchin monkeys affect their ability to discover and exploit new food sources. We also analyse the factors that affect the finder's share and the total amount of food obtained by the finder from a newly discovered resource. By placing platforms filled with bananas at novel locations in their home range, we show that animals in the leading edge of a foraging group have a higher probability of discovering new food sources than animals occupying other spatial positions. The alpha male and the alpha female, which tended to occupy central-forward positions, were able to monopolize newly discovered food sources and thus obtain a major share of them. The finder's share at the feeding platforms was smaller when there was more food on a platform, but increased with longer delays before the arrival of other individuals. The total amount of food obtained by the finder from the feeding platforms was larger when there was more food on the platform, when the finder was of higher social status, and when it took longer for other individuals to arrive. Animals can increase their finder's share and total amount consumed from a newly discovered resource by keeping large interindividual distances and by avoiding giving cues about the presence of food (such as food-associated vocalizations) to other animals.

Abstract: The social behaviour of adult female mountain goats, Oreamnos americanus, was studied for 2 years in an unhunted population in west-central Alberta, Canada. Compared with other female ungulates, mountain goat females interacted aggressively much more frequently and their dominance ranks were less stable in time and less age-related. Goats were organized in a non-linear but non-random dominance hierarchy, with many reversals in rank. The best morphological predictor of dominance rank was horn length one year and body mass in the following year. Age was a weaker predictor of dominance status than what has been reported for other female ungulates. The ranks of individual goats changed between years and dominance rank one year was not a good predictor of rank the following year. These results suggest that linearity may only be possible when a contested resource can be defended. Dominant female goats did not forage more efficiently than subordinate goats, and dominant status did not affect the amount of time devoted to alert behaviour.

Abstract: Individuals in a foraging group of wild bronwn capuchin monkeys choose different spatial positions relative to the rest of the group. Markov analysis of sequencess of individual spatial positions demonstrated significant differnces between individuals, which coul be categorized a posteriori into four homogenous subgroups. An individual's spatial position was related primarily to the amount of aggression it received from the group's dominant male, but also varied with its sex. Spatial choice varied with changes in an individual's social status, but did not vary consistently with seasonal differences in food availability. These results support the hypothesis that individuals compete for preferred spatial positions within a foraging group.

Abstract: previous termSocial cognition,next term in particular the derivation of previous termsocialnext term information from observation of interactions between members of a previous termsocialnext term group, has been widely investigated in primates, but it has received little attention in other previous termsocialnext term mammals, although it has been anecdotally reported in the previous termdomestic dog,next term Canis familiaris. We recorded the behaviour of previous termdogsnext term (“spectators”) that had observed controlled interactions between a human and a previous termdognext term (the “demonstrator”) competing for an object, and that were subsequently allowed to interact freely with both participants. When the competitions were playful, as indicated by signals performed by the human, the spectator was more likely to approach the winner first and/or more rapidly, suggesting that winners of games are perceived as desirable previous termsocialnext term partners. When the human did not perform play signals, changing the previous termsocialnext term context from play to contest over a resource, spectators were slower to approach either of the participants, suggesting that participants in contests were less desirable as previous termsocialnext term partners than participants in games. If the previous termdognext term was prevented from seeing the game, it still reacted differently to the winner and the loser, but its behaviour was not the same as after games that it had seen. We conclude that spectator previous termdogsnext term gain information from the players' subsequent behaviour as well as from direct observation of the game.

Abstract: Theory predicts that individuals living in fission-fusion societies, in which group members frequently change subgroups, should modify grouping patterns in response to varying social and environmental conditions. Spotted hyaenas, Crocuta crocuta, are long-lived carnivores that reside in permanent social groups called clans. Clans are complex, fission-fusion societies in which individual members travel, rest and forage in subgroups that frequently change composition. We studied two clans in Kenya to provide the first detailed description of fission-fusion dynamics in this species. Because social and ecological circumstances can influence the cohesiveness of animal societies, we evaluated the extent to which specific circumstances promote the formation of subgroups of various sizes. We found that cooperative defence of shared resources during interclan competition and protection from lions were cohesive forces that promoted formation of large subgroups. We also tested hypotheses suggesting factors limiting subgroup size. Mothers with small cubs avoided conspecifics, thereby reducing infanticide risk. Victims of aggression either reconciled fights or separated from former opponents to reduce the immediate costs of escalated aggression in the absence of food. As predicted by the ecological constraints hypothesis, hyaenas adjusted their grouping patterns over both short and long time scales in response to feeding competition. Crocuta were most gregarious during periods of abundant prey, joined clanmates at ephemeral kills in numbers that correlated with the energetic value of the prey and gained the most energy when foraging alone because cooperative hunting attracted numerous competitors. Overall, our findings indicate that resource limitation constrains grouping in this species.