Abstract: Third-party interventions are defined as the interruption of dyadic interactions by third animals through direct physical contact, interposing or threats. Previous studies focused on the analysis of interventions against agonistic encounters. However, there have been no evaluations of interventions against affiliative behaviours, particularly in relation to the intervening animal�s social relationships and its social and spatial position. Horses, Equus caballus, are an interesting model species, as interventions against affiliative interactions occur more frequently than against agonistic interactions. In this study, 64 feral horses displayed 67 interventions in affiliative interactions and eight interventions in agonistic interactions within the observation period. We analysed the interventions in affiliative encounters, and found that it was mainly higher-ranking females that intervened in the affiliative interactions of group mates in the stable horse harems. The intervening animals took an active part in affiliative and agonistic encounters within the group, but did not occupy particular social roles or spatial positions. They intervened in affiliative interactions in which group mates with which they had social bonds interacted with other members of the group. They targeted the nonbonded animal and approached the one with which they were socially bonded. We suggest some species use third-party interventions in affiliative interactions to prevent competition for preferred social interaction partners from escalating into more costly agonistic encounters.

Abstract: Darwin’s claim of differences in mental abilities between man and other animals is a matter of degree rather than of kind and appears to apply nicely to a comparison of choice behaviour in humans and equine. Humans and horses make two kinds of decisions, fast reflexive decisions based on heuristics, and slower more considered decisions that require more complex cognitive processing. Heuristic use is adaptive in that decisions based on them are most often useful in helping an organism to survive while requiring little time and cognitive effort. There is considerable evidence that there is an innate basis to many heuristics in humans as well as horses. A case will be made that the investigation of heuristics specific to horses will lead to an understanding of equine behaviour that has not been possible using traditional learning theories alone. Traditional learning theories are restricted in explaining behaviour to appeals to reinforcement regimes or to the formation of associations between novel stimuli and stimuli that cause innate reflexes, but they are of no use when behaviour is controlled by stimuli that have never been reinforced or been systematically paired with other stimuli that cause reflexive responses. For example, a horse in a two-choice discrimination task may choose a familiar stimulus which has never been reinforced over a new stimulus added to the discrimination task, simply due to the use of an heuristic that usually works -- when in doubt, choose a more familiar object over an unfamiliar one. Conflict resolution strategies provide another good example of heuristic vs. slow decision making. In both humans and horses, conflict resolution strategies are used within, but not typically between social groups. Such groups can be defined as community of interest. Depending on the resource that has to be defended, groups may well be small identities, such as human families or horse harems, or large aggregations such as herds in horses, or religious groups or nations in humans. Fast and simple resolution is possible with stable social identities in simple environments, but more complicated and time consuming deliberative processes are required to resolve conflict over long-term resource acquisition, for decisions in complex conflicts situations and complex social settings.

Abstract: Like many other herbivores equids feed on rather evenly distributed resources. Especially in ruminants several studies have proved the influence of social organisations, rank, sex and the depletion of feeding sites on the feeding behaviour of individuals. However, it is not yet understood whether social aspects affect horses´ feeding decisions. Horses roam on vast habitats with constantly changing vegetation. In non-competitive situations domestic horses tend to return to the same feeding site until it is overgrazed. Whereas, for competition over limited food the social status of the individuals appears to be important. Curiosity about the influence of social rank and different social feeding conditions on the horses´ feeding decisions between two buckets, equally filled with high-quality surplus food, led us to create the test situation described here. The observer horses were alternately tested with a dominant and a subordinate demonstrator placed in one of three different positions. We conclude that domestic horses use cognitive strategic decision making in order to decide where to feed in a social feeding situation. When possible they tend to return to the same, continuously supplied feeding site and switch to an “avoidance tendency” when another horse is already feeding from it or in the presence of a dominant horse. Thus the position and the social rank of conspecifics affect the feeding strategy of horses.