The pivotal role of rank in grooming and support behaviour in a captive group of bonobos (Pan paniscus)

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. Seyfarths 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 Seyfarths 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

An experimental evaluation of the consistency of competitive ability and agonistic dominance in different social contexts in captive bonobos

Bonobos have been described as a relatively egalitarian and female dominant species. The exact nature and quality of their dominance relationships and the existence of female dominance are current topics of dispute. We investigated the consistency across social contexts, the stability in time, and the degree of expression of the competitive feeding ability and agonistic dominance in a captive group of bonobos. First, we examined whether the competitive feeding ranks and agonistic ranks differed in different dyadic contexts, triadic contexts and the whole group context. For some pairs of animals the dominance relationships with respect to competitive feeding altered with different group compositions. The agonistic dominance relationships changed accordingly. The competitive feeding ranks and agonistic ranks in the experiments correlated strongly with each other. The alpha position was occupied by a female, but not all females outranked all males. We suggest that females can profit from each others presence to gain inter-sexual dominance. Second, although the agonistic rank order in the whole group remained the same over at least five years, some dyadic competitive feeding ranks changed over time, resulting in a stronger female intersexual dominance. Third, the degree of expression of the behaviors used to quantify dyadic competitive and agonistic dominance was not high, in line with the popular egalitarian epithet. Notwithstanding its low consistency across contexts, the dominance hierarchy in the whole group has a strong predictive value for other social relationships such as grooming. Given this strong effect of rank on other behaviours and given the strong dependency of rank on social context, the choice of the right party members may be a crucial factor in the fission-fusion processes of free-ranging bonobos

Behavior and health issues in Bengal cats as perceived by their owners : a descriptive study

The Bengal cat is a recently established hybrid cat breed that was created by crossbreeding the domestic shorthair cat (Felis silvestris catus) and the wild Asian leopard cat (Prionailurus bengalensis). In spite of its popularity, research on behavior and health issues in this breed remains limited. A questionnaire was sent to Bengal cat owners in Flanders and Wallonia (Belgium), and the Netherlands to document the suitability of the breed as a pet from the point of view of the owners by exploring the presence of behavioral and health issues that may provoke the cat?s relinquishment. It included questions about their decision to own a Bengal cat, the cat demographics and living environment, potential undesirable behaviors, and health issues. The owners of 60.5% (n = 155) of cats chose this breed due to a combination of looks and character. For most cats (99.2% n = 254), the respondents looked for information about the breed before acquiring a cat. Breed-typical health conditions, as described by International Cat Care, were reported in 9.9 % (n = 24) of cats, with being overweight as the most common one. The most frequent behaviors were climbing (89.5%, n = 229), vocalizing (88.7%, n = 227), playing with water (79.7%, n = 204), and hunting (78.9%, n = 202). These were, however, rarely considered problematic by the owners. The most frequent behaviors often classified as problematic by the owners were destructive behaviors (33.2%, n = 85), followed by pica (16.4%, n = 42), aggression toward animals (16%, n = 41), and urination outside the litter tray (13.3%, n = 34). There were no significant differences between cats from early and later generations nor between cats with and without outdoor access. The fact that most owners looked for information about the breed before acquiring the cat and that the most frequently displayed behaviors were not considered problematic by their owners could translate into a lower incidence of relinquishments. Nevertheless, some of those behaviors may still be indicative of welfare issues, independently of the owner?s perception. Further and more in-depth research is needed to understand the potential issues of keeping Bengal cats as pets

Development of hierarchy and rank effects in weaned growing rabbits (oryctolagus cuniculus)

[EN] Aggression among growing rabbits reduces production efficiency, and negatively affects the animal s welfare. Understanding hierarchy development may improve its predictive value with regard to differential access to resources and fitness. This could in turn lead to measures to reduce aggression. This study quantifies the development of a hierarchy among small groups of same-age rabbits kept in high density. We describe the development of the hierarchy in four mixed-sex groups formed after weaning at four weeks of age. The relationships between rank and aggressiveness, weight, sex and wound count were examined. To balance possible genetic effects, each group contained four full sibling dyads (N=8) with the male and female coming from the same litter (total N=32). Each group was housed in a wire mesh cage of 0.72 m² and was observed at 4, 6, 8, 10 and 12 wk of age. All activities of focal individuals were scored and antagonistic interactions among all group members were sampled continuously. For rank order analysis, submissive behaviours shown after receiving aggression were used. Females were heavier than males (3.2 kg vs 3.0 kg: wk 12); this difference was statistically significant from the sixth week onwards. Two of the four groups developed significantly linear hierarchies from the age of ten and twelve weeks onwards, respectively. In these two groups, rank order did not correlate with body weight, sex or wound count. The group with the steepest hierarchy had the highest number of wounds. The results show that growing rabbits can form linear hierarchies by 10 weeks of age, but this tendency differs strongly among groups. The male and female rabbits did not form separate hierarchies, in contrast to their natural tendencies. This may be due to the high density, and may imply a lack of interaction freedom.Vervaecke, H.; De Bonte, L.; Maertens, L.; Tuyttens, F.; Stevens, J.; Lips, D. (2010). Development of hierarchy and rank effects in weaned growing rabbits (oryctolagus cuniculus). World Rabbit Science. 18(3). doi:10.4995/wrs.2010.822918

Male Mating Tactics in Captive Rhesus Macaques (Macaca mulatta): The Influence of Dominance, Markets, and Relationship Quality

Male mating success in a multimale–multifemale group can depend on several variables: body condition, dominance, coalitions, “friendship,” or an exchange of services for mating access. Exchange patterns may also be determined by market effects or social relationships. We studied the mating tactics of males in a captive, multimale–multifemale group of rhesus macaques and the resulting patterns of mating and paternity to determine the influence of dominance rank, mating markets, and relationship quality on their mating tactics. Male rank was positively related to the total number of copulations and the number of mating partners, but did not explain male mating distribution completely. Moreover, male fertilization success was not related to male rank. Males did not exchange grooming for mating access on the same day and neither the supply nor the rank (as a proxy for quality) of receptive females affected the amount of male grooming, suggesting that market effects did not explain male mating access. However, there was a positive correlation between long-term grooming patterns of both males and females and mating access, indicating that social relationships were important for male mating access. Paternity data revealed that these social relationships were also important for male reproductive success. We conclude that both male rank and male–female “friendship” determined male mating access in these rhesus macaques, but that “friendship” was more important in determining paternity, emphasizing the importance of intersex social bonds in male mating success in multimale primate societies

Food site residence time and female competitive relationships in wild gray-cheeked mangabeys (Lophocebus albigena)

Authors of socioecological models propose that food distribution affects female social relationships in that clumped food resources, such as fruit, result in strong dominance hierarchies and favor coalition formation with female relatives. A number of Old World monkey species have been used to test predictions of the socioecological models. However, arboreal forest-living Old World monkeys have been understudied in this regard, and it is legitimate to ask whether predominantly arboreal primates living in tropical forests exhibit similar or different patterns of behavior. Therefore, the goal of our study was to investigate female dominance relationships in relation to food in gray-cheeked mangabeys (Lophocebus albigena). Since gray-cheeked mangabeys are largely frugivorous, we predicted that females would have linear dominance hierarchies and form coalitions. In addition, recent studies suggest that long food site residence time is another important factor in eliciting competitive interactions. Therefore, we also predicted that when foods had long site residence times, higher-ranking females would be able to spend longer at the resource than lower-ranking females. Analyses showed that coalitions were rare relative to some other Old World primate species, but females had linear dominance hierarchies. We found that, contrary to expectation, fruit was not associated with more agonism and did not involve long site residence times. However, bark, a food with a long site residence time and potentially high resource value, was associated with more agonism, and higher-ranking females were able to spend more time feeding on it than lower-ranking females. These results suggest that higher-ranking females may benefit from higher food and energy intake rates when food site residence times are long. These findings also add to accumulating evidence that food site residence time is a behavioral contributor to female dominance hierarchies in group-living species

Measuring and testing the steepness of dominance hierarchies

In the analysis of social dominance in groups of animals, linearity has been used by many researchers as the main structural characteristic of a dominance hierarchy. In this paper we propose, alongside linearity, a quantitative measure for another property of a dominance hierarchy, namely its steepness. Steepness of a hierarchy is defined here as the absolute slope of the straight line fitted to the normalized David’s scores (calculated on the basis of a dyadic dominance index corrected for chance) plotted against the subjects’ ranks. This correction for chance is an improvement of an earlier proposal by de Vries (appendix 2 in de Vries, Animal Behaviour, 1998, 55, 827–843). In addition, we present a randomization procedure for determining the statistical significance of a hierarchy’s steepness, which can be used to test the observed steepness against the steepness expected under the null hypothesis of random win chances for all pairs of individuals. Whereas linearity depends on the number of established binary dominance relationships and the degree of transitivity in these relationships, steepness measures the degree to which individuals differ from each other in winning dominance encounters. Linearity and steepness are complementary measures to characterize a dominance hierarchy

Dominance, fatness and fitness in female American bison, Bison bison

In females of several mammalian species, it is becoming evident that benefits related to high dominance rank can result in increased fitness, albeit to a lesser degree than in males. We examined indicators of fitness in relation to dominance rank in a group of adult female American bison in semifree-ranging conditions. A significantly linear dominance hierarchy was found. Dominance rank correlated significantly with three indicators of body condition: weight, speed of hair loss and fatness. After statistical correction for the other two factors, only the link between rank and fatness remained significant. Dominant females did not show higher fecundity, nor did their daughters. Combining the results over the study years, we found that weight of offspring at weaning correlated significantly with maternal rank. © 2005 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.status: publishe