Abstract: The purpose of the following study was to determine if head partitions would facilitate feeding by subordinate horses in the presence of dominant pen-mates. Six pairs of mares, each with established dominant-subordinate relationships, were allowed to compete for feed in a 112-cm trough following 24 h of deprivation. Time spent feeding by each mare in each pair was recorded with a wire-mesh partition, a solid plywood partition or no partition dividing the trough. Differences in feeding times between dominant and subordinate mares were greatest in the absence of a partition and least (P<0.05) with the wire barrier in place. Differences in feeding times with the solid plywood barrier were not significantly different from either of the other treatment conditions. It was concluded that head partitions on a trough facilitate feeding by subordinate horses in the presence of dominant pen-mates and thus provide a more equitable distribution of food resources.

Abstract: Diplôme de recherche universitaire: neurosciences comportementales: Université d'Aix-Marseille II. Faculté des sciences de Luminy Marseille (FRA)* 117p

Abstract: Interventions in aggressive disputes were investigated in a free-living troop of vervets (Cercopithecus aethiops sabaeus) in Barbados. Interventions on behalf of kin were more frequent than on behalf of non-kin. Both types of interventions were more likely when the intervening animal outranked the opponent; presumably because retaliation probability, and hence cost of intervening, is low against low ranking opponents. The number of interventions given on behalf of both kin and non-kin increased with the number of disputes in which they were involved. In contrast to kin interventions, the number of interventions given on behalf of non-kin was correlated with that received by non-kin, suggesting that reciprocation is a necessary component of non-kin interventions. Non-kin interventions were more likely when the recipient outranked the opponent, presumably because reciprocation probability is high. Pairs of non-kin form structured reciprocal relationships based on the proportion of interventions allocated to each other, and most non-kin interventions flowed through these relationships. Males intervened on behalf of non-kin more frequently than did females. The implications of the results for the evolution of kin and reciprocal altruism were discussed.

Abstract: Abstract Horse flies (Tabanidae) on and around feral ponies in harem groups were counted at Assateague Island National Seashore, Maryland, U.S.A., between June and August 1985. Harem stallions attracted the most flies; adult mares showed intermediate fly numbers, while few flies landed on foals under any circumstances. The use of thermal and chemical cues by flies selecting a host may have helped create this disparity. When flies were abundant, ponies reduced spacing within the group. Ponies in larger groups suffered from fewer flies than ponies in smaller groups. There was, however, no evidence that ponies merged into larger groups in response to fly harassment, suggesting that biting flies play little role in structuring pony social organization.