Abstract: A short-term study was made of 2 groups of Przewalski horses, a bachelor group of 4 juvenile stallions in Ooij Polder and a harem group of 1 stallion and 4 mares. All social interactions were recorded and the nearest and farthest neighbour was noted. Correspondence analysis was used to determine what parameters determined the relationships among the horses. There was a linear hierarchy among the bachelor stallions. The dominant stallion of the group was also the oldest. The hierarchy was not linear in the harem group, and the 3-year-old stallion was subordinate to the 5-year-old mares. He was also most likely to be farthest from other horses. The mares of the same age, who had also arrived in the park at the same time, tended to be one another's nearest neighbours. The frequency of aggression is higher among Przewalski horses than among domestic horses of similar ages. Correspondence analysis revealed that head-threats and other forms of aggression accounted for more of the variance in the data than any other behaviour, but submission, play and social interactions also contributed.

Abstract: Agonistic intervention behavior was observed in captive groups of chimpanzees (Pan troglodytes), rhesus monkeys (Macaca mulatta), and stumptail monkeys (M. arctoides). Reciprocity correlations of interventions were determined while removing from the data the effects of several symmetrical relationship characteristics, that is, matrillineal kinship, proximity relations, and same-sex combination. It was considered likely that if significant reciprocity persisted after controlling for these characteristics, the reciprocity was based on cognitive mechanisms. Statistical significance was tested by means of recently developed matrix permutation procedures. All three species exhibited significant reciprocity with regard to beneficial interventions, even after controlling for symmetrical traits. Harmful interventions were, however, reciprocal among chimpanzees only. This species showed a “revenge system”, that is, if A often intervened against B, B did the same to A. In contrast, both macaque species showed significantly inversed reciprocity in their harmful interventions: if A often intervened against B, B rarely intervened against A. Further analysis indicates that the strict hierarchy of macaques prevents them from achieving complete reciprocity. Compared to chimpanzees, macaques rarely intervene against higher ranking group members. The observed contrast can be partially explained on the basis of differences in available space, as indicated by a comparison of indoor and outdoor living conditions for the chimpanzee colony. Yet, even when such spatial factors are taken into account, substantial behavior differences between chimpanzees and macaques remain.

Abstract: lsquoLekrsquo breeding systems, where males defend small, clustered mating territories, are thought to occur where the distribution of females is heavily clumped but males are unable to defend resources used by females. In this paper, we describe a breeding system in fallow deer where males are able to defend resources used by females but the most successful bucks instead defend small territories on a traditional mating ground; where the lek is sited in an area not heavily used by females at other times of year and is visited primarily by females in or close to oestrus; and where mating success on the lek is related to territory position and to male phenotype but not to the resources available on different lek territories. Comparisons with other ungulates suggest that lek breeding species fall into two groups: those where leks are regularly visited by herds of females many of which are not in oestrus and those, like fallow deer, where leks are visited primarily by oestrous females. In the latter species, it is unlikely that females visit the lek for ecological reasons.