Abstract: Abstract  Based on previous research in captivity, bonobos, Pan paniscus, have been called a female-bonded species. However, genetic and behavioural data indicate that wild females migrate. Bonding between these unrelated females would then be in contradiction with socio-ecological models. It has been argued that female bonding has been overemphasized in captive bonobos. We examine patterns of proximity, grooming and support behaviour in six well established captive groups of bonobos. We find that female bonding was not a typical characteristic of all captive bonobo groups. In only two groups there was a trend for females to prefer proximity with other females over association with males. We found no evidence that following or grooming between females was more frequent than between males and unrelated females or between males. Only in coalitions, females supported each other more than male-female or male-male dyads. We also investigated five mother-son pairs. Grooming was more frequent among mothers and sons than in any other dyad, but sons did not groom their mothers more than males groomed unrelated females. Mothers groomed their sons, or provided more support to them than females groomed or supported unrelated males. Thus, while bonds between females were clearly present, intersexual relations between males and either unrelated females or their mothers are of more, or equal importance.

Abstract: We investigated dyadic grooming relationships in a captive group of bonobos (Pan paniscus) and questioned what social function grooming fulfils in the 'market of services and favors'. Hereto we examined which of two theoretical models – grooming for support (Seyfarth, 1977, 1980) or grooming according to the similarity principle (de Waal & Luttrell, 1986) – best accounted for the observed grooming distribution. Similarity in traits did not correlate with increased grooming or close proximity among the individuals. Therefore, the similarity hypothesis was rejected. Seyfarth's model of rank-related grooming was largely confirmed. The animals distributed their grooming according to the rank of the receivers. We found an exchange between grooming and receipt of support. There was more grooming up than down the hierarchy. However, not all predictions about rank-related competition over grooming were confirmed. We found that dyadic grooming reciprocity indeed increased with decreasing rank distance. Yet, there was no increase of grooming within the dyad with decreasing rank distance and high ranking individuals were not competed over at the highest rates. The observed correlation between grooming and support received represents an important fit with Seyfarth's prediction, but does not allow for conclusions about underlying causal processes. Other causal explanations, besides the 'groom to receive support' hypothesis, that could explain a similar correlation are discussed.

Abstract: Feral horses are social animals, which have to rely on survival strategies centered on the formation of cohesive social bonds within their bands. Many problems in the husbandry of social animals such as horses, are due to the fact that the limits of their adaptive abilities are exceeded. Evidence suggests that the fundamental social characteristics of domestic horses have remained relatively unchanged. The social structure, social strategies and social interactions were investigated (3 non-consecutive years, 24 hr per day for several weeks) in long term established groups of domestic horses (mares and geldings of all ages) and a few small introduced groups, kept in (semi)natural environments. The general aim was to investigate the social needs of domestic horses. The social life of domestic horses was characterised by long lasting bonds with preferred partners which were established and maintained by allogrooming, play, proximity and dominance behaviours. Bonding partners were mainly found within the same sex-age group, but adult geldings also bonded with sub-adult mares and geldings. Adult mares were clustered in a group, while the other animals formed a second group. Among the adult mares, subgroups according to reproductive state were formed. Individuals regulated their social network by interfering with interactions between other members of the herd, which in itself is complex. An intervention is a behavioural action of one animal that actively interferes with an ongoing interaction between a dyad with the apparent aim of altering that interaction. This was verified by post-hoc analyses of disturbed and undisturbed interactions. Interventions in allogrooming or play were performed significantly more often when at least one member of the initial dyad was a preferred partner of, or familiar to (within the small introduced bands) the intervener. The stronger the preferred association in allogrooming between the intervener and member(s) of the initial dyad, the higher the probability the intervener would displace one initial member and continue allogrooming with the other. Just five behaviours were extracted which reliably reflected the dominance relations among horses. Aggression with the hind quarters was used both offensively and defensively and therefore not suitable as a reliable parameter. Individual dominance relationships were related to social experience. The implications of these findings for horse husbandry were assessed. It is argued that the execution of affiliative behaviours may be rewarding in itself, and therefore always will be a highly motivated behaviour. It is shown that social positive physical interactions (allogrooming, play) with other horses is an ethological need and therefore indispensable in modern husbandry systems. Ethological needs are so important for the animal that husbandry systems that lack the possibilities to execute such behaviours will cause chronic stress. It is concluded that all horses need physical social contact, and that horses, which lack appropriate social learning experiences during ontogeny, may be hampered in their social functioning later in life. Solutions for problems, including dominance problems, in individual social housing and group housing are presented.

Abstract: Appleby (1983, Anim. Behav., 31, 600-608) described a statistical test, based on the work of Kendall (1962, Rank Correlation Methods), for the significance of linearity in dominance hierarchies. He suggested that unknown relationships should be assigned the value 1/2 and that subsequently the same test procedure can be used. In this paper it is shown that incorrect results are obtained by this method whenever there are unknown relationships. Values of the linearity index are systematically too low. P-values can be too high (underestimating the significance) or too low (overestimating), and seem to differ by not much more than a factor two (respectively a half) from the correct P-value. An improved method is developed for testing linearity in a set of dominance relationships containing unknown relationships. Furthermore, it is argued that, if one admits the possibility of tied dominance relationships, which should indeed be assigned the value 1/2, Landau's linearity index is to be preferred to Kendall's index. A randomization test is developed for assessing the significance of linearity or non-linearity in a set of dominance relationships containing unknown or tied relationships. The test statistic employed in this testing procedure is based on Landau's linearity index, but takes the unknown and tied relationships into account.

Abstract: We observed the activity and movements of Konik horses (Equus caballus) in order to determine the initiators of movements and the individuals taking the lead in movements of the main groups. We conducted our observations between March-June 2010 along the shores of the Rhine river, in the Blauwe Kamer reserve, in the Netherlands. The horses were introduced to the reserve alongside with cattle to prevent the growth of the forest and maintain the grass habitat. We videotaped all observations on two digital video cameras, one providing the general view of the group and the other scanning and focusing on the individuals, to aid with identification. Horses were recognized based on individual profiles that were created for each one, consisting of photos of both sides and notes of the main characters, such as orientation and coloration of the mane, prominent scars and markings, etc. Twenty three horses (not counting foals) were organized in two harem groups with 11 individuals (two of which were dominant stallions) in the large group and six individuals (one of which was a stallion) in the second group. These two main groups were always within sight of each other, and two bachelor males moved usually in their vicinity. An additional group of three young bachelor males roamed elsewhere in the reserve. We divided the movements of the horses to local movements while grazing and to long-distance movements, in which the horses moved to a different grazing location, to a pond of water, resting area or groups of trees that were used by the horses for scratching themselves. During the local movements, any two of the three oldest females in the large harem group were enough to cause the whole group to follow them and gradually change position within the pasture. The smaller harem always followed the large harem’s movements. The long-distance movements of the large harem were sometimes initiated by one of the harem stallions that herded their group and at other times – by the oldest females. Soon after the movement was clearly initiated, the dominant stallions positioned themselves in the back of the group or in the center and had no influence on the direction of move that was only determined by the leading females. In the long-distance movements too, the small harem followed the large harem group, and the two bachelor males usually followed behind them. Social interactions included aggressive interactions between the two dominant males within the large harem or between dominant stallions and the two bachelor males accompanying the two harems. In addition, dominant males courting or attempting to mate with mares sometimes caused a turmoil that eventually initiated movement of the harems. KW -