Abstract: Male horses (Equus caballus) defend harems of females (bands) year-round and throughout their lifetimes. A male's lifetime reproductive success depends upon the number of females in his harem. Although harems have previously been reported as remaining stable over many years, during the two years of this study 30 % of the adult females in an island population of feral horses changed harems during late winter. The seasonal differences in harem stability resulted from seasonal differences in the abundance and distribution of food. The spacing between band members was greater and the frequency of social interactions between them was lower in winter than in summer. In addition, the amount of time devoted to grazing increased in winter. These differences are attributed to the lower availability of suitable vegetation duirng winter. Harem stability did not depend on the age of females, the size of the harem, nor the age of the harem stallion, but did depend on the presence of subordinate stallions attached to the band. All of the females that changed bands left single-male bands; multi-male bands were stable throughout the study.

Abstract: Monkeys recognize the social relations that exist among others in their group. They know who associates with whom, for example, and other animals' relative dominance ranks. In addition, monkeys appear to compare types of social relations and make same/different judgments about them. In captivity, longtailed macaques (Macaca fascicularis) trained to recognize the relation between one adult female and her offspring can identify the same relation among other mother-offspring pairs, and distinguish this relation from bonds between individuals who are related in a different way. In the wild, if a vervet monkey (Cercopithecus aethiops) has seen a fight between a member of its own family and a member of Family X, this increases the likelihood that it will act aggressively toward another member of Family X. Vervets act as if they recognize some similarity between their own close associates and the close associates of others. To make such comparisons the monkeys must have some way of representing the properties of social relationships. We discuss the adaptive value of such representations, the information they contain, their structure, and their limitations.

Abstract: n a herd of semi-captive plains zebras interventions, which occurred within the harems, were investigated in order to answer the question why zebras interfered. These interventions are of interest because they regulate the contacts between companions and because, as corrective and preventive measures, they reveal the normative principles underlying the behaviours by which animals structure their social environment. An attempt was made to deduce 1) the internal norms of the interferer; 2) his short term aims; 3) his tactis and 4) his perception of the social environment. The analysis revealed that in the case of an affiliative interaction foals, yearlings and adult mares started to interfere if a friend had an affiliative contact with another zebra. In view of the interferer's behaviours it was concluded that their aim was to break off the ongoing interaction and that zebras tended to protect friendship bonds. Foals and yearlings further interfered if their mother was being threatened, attacked or sexually approached by a stallion. In view of the interferer's behaviours its aim was to prevent iminent interactions or to break off ongoing interactions. This suggests that these interventions were of a protective nature. The interferer's behaviours in both contexts ware very much alike. Mares tended to interfere if their foal/yearling or adult daughter was threathened or aggressed or if a mare friend was being sexually approached by a stallion. This type of intervention was of a protective nature. Stallions in a multi male harem showed a high tendency to interfere in courtship interactions. From the resemblance between interventions in courtship and in aggressive interactions it is concluded that, at leat in a number of cases, the individuals have perceived courtship behaviour by the stallion as a threat towards the mare involved.

Abstract: Research on reciprocity is impaired by confusing definitions and often wrongly used statistical tests. Here, two models of the mechanism on which reciprocity may be based are discussed and an initial step towards a new fremework for its analysis is presented. A distinction is made between reciprocity and interchange. In the case of reciprocity, for one kind of act the same kind is received in return. In interchange, however, two different kinds of acts are bartered. Three types of reciprocity/interchange in social actions among all pairs of group-members are distinguished ([`]qualitative', [`]relative' and [`]absolute') on the basis of the precision of the reciprocity/interchange. Permutation procedures for association between matrices (such as the Mantel Z and two other newly derived tests) are used as a statistical test for detecting reciprocity/interchange. A rough comparison of the power of the two new tests is included. The tests can be applied to all kinds of group-living animals and to all sorts of social behaviour. The distinction between the three types of reciprocity/interchange and the matching statistical methods are also useful for defining and detecting other patterns in social interactions, like unidirectionality and associations between different kinds of social behaviour. The influence on social interactions of variables like dominance rank, age and sex can be analysed in the three forms by testing correlations between invented matrices which represent the influence of these variables (the so-called hypothesis matrices) and social interaction matrices. These methods are extended for two categories of individuals, thus allowing the investigation of, for example, reciprocity between males and females. The methods are illustrated with examples of coalition formation and grooming behaviour among captive chimpanzees, Pan troglodytes.

Abstract: The ability of ponies to learn to avoid a relatively novel food associated with illness was tested in three situations: when illness occurred immediately after consuming a feed; when illness occurred 30 min after consuming a feed; and when illness was contingent upon eating one of three feeds offered simultaneously. Apomorphine was used to produce illness. The feeds associated with illness were corn, alfalfa pellets, sweet feed and a complete pelleted feed. The ponies learned to avoid all the fees except the complete feed when apomorphine injection immediately followed consumption of the feed. However, the ponies did not learn to avoid a feed if apomorphine was delayed 30 min after feed consumption. They could learn to avoid alfalfa pellets, but not corn, when these feeds were presented with the familiar “safe foods,” oats and soybean meal. Ponies apparently are able to learn a taste aversion, but there were constraints on this learning ability. Under the conditions of this study, they did not learn to avoid a food that made them sick long after consumption of the food, and they had more difficulty learning to avoid highly palatable feeds.