Social relations in a mixed group of mules, ponies and donkeys reflect differences in equid type

Donkeys and mules are frequently kept as companion animals for horses and ponies, with these different equids often being considered a homogenous group. However, the extent to which domestic equids form inter-specific bonds and display similar social behaviour when living in a mixed herd has not previously been studied. Here we compare the social organization of these three (sub)species when housed together, providing the first systematic analysis of how genetic hybridization is expressed in the social behaviour of mules. A group of 16 mules, donkeys and ponies was observed for 70h and preferred associates, dominance rank and the linearity of the group's hierarchy was determined. The different equids formed distinct affiliative groups that were ordered in a linear hierarchy with ponies as the most dominant, mules in the middle ranks and donkeys in the lowest ranks. Within each equid subgroup, the strength of the hierarchy also varied. Thus in the present study, the three (sub)species displayed different social organization and levels of dominance and preferred to associate with animals of the same equid type, given the opportunity. These results suggest that different domestic equid (sub)species display variations in social behaviour that are likely to have a strong genetic basis.     

Male and female agonistic and affiliative relationships in a social group of farm cats (Felis catus L.)

A dominance hierarchy based on the outcome of agonistic encounters was found among male and female domestic cats. A female dominated over some males. The dominance concept is also discussed in terms of social bonding. The relationships among adult females were amicable, whereas adult males showed reciprocal tolerance. The flow of affiliative behaviour was directed mainly from females to one male of the group. The analysis of marking behaviour showed that this male sprayed urine and rubbed the perioral and cheek regions of the face on the objects of the environment at a higher rate than the other members of the group. Nevertheless, rubbing the perioral and cheek regions of the face on objects was not correlated to dominance rank, possibly because it has some function in social communication other than territorial defence against strangers. No relationships have been found between claw scratching, rolling on the ground and social rank, or between the former and other marking behaviour. It is concluded that claw scratching and rolling were not utilised to mark territory.     

The reproductive correlates of social hierarchy in laboratory male mice

In laboratory male mice the effects of social hierarchy on hormonal and spermatogenic testicular function, accessory organs and testicular weights, sexual behaviour have been investigated using an experimental model of social hierarchy, which is characterised by a minimal size (two male mice) and 5 days period of social interactions. The social rank of the partners was detected by asymmetry in aggressive behaviour. Using the experimental condition, when the both partners have no preferences for exclusive use of area we demonstrated that there were no rank differences in the number of mounts and testicular testosterone content. Nevertheless a rank asymmetry in the male sniffing behaviour towards a receptive female, weights of the testes, seminal vesicles, epididymes and the number of epididymal sperm was kept up in a stable social group. Social dominance was found to affect negatively on testicular testosterone increase in response to introduction of a receptive female and sexual attractiveness of male to a receptive female in both dominant and subordinate males. The results obtained demonstrate the impact of social hierarchy on reproduction in laboratory male mice, particular in respect of spermatogenesis and the testicular testosterone in response to a receptive female.     

An individual-oriented model on the emergence of support in fights, its reciprocation and exchange

Complex social behaviour of primates has usually been attributed to the operation of complex cognition. Recently, models have shown that constraints imposed by the socio-spatial structuring of individuals in a group may result in an unexpectedly high number of patterns of complex social behaviour, resembling the dominance styles of egalitarian and despotic species of macaques and the differences between them. This includes affiliative patterns, such as reciprocation of grooming, grooming up the hierarchy, and reconciliation. In the present study, we show that the distribution of support in fights, which is the social behaviour that is potentially most sophisticated in terms of cognitive processes, may emerge in the same way. The model represents the spatial grouping of individuals and their social behaviour, such as their avoidance of risks during attacks, the self-reinforcing effects of winning and losing their fights, their tendency to join in fights of others that are close by (social facilitation), their tendency to groom when they are anxious, the reduction of their anxiety by grooming, and the increase of anxiety when involved in aggression. Further, we represent the difference in intensity of aggression apparent in egalitarian and despotic macaques. The model reproduces many aspects of support in fights, such as its different types, namely, conservative, bridging and revolutionary, patterns of choice of coalition partners attributed to triadic awareness, those of reciprocation of support and 'spiteful acts' and of exchange between support and grooming. This work is important because it suggests that behaviour that seems to result from sophisticated cognition may be a side-effect of spatial structure and dominance interactions and it shows that partial correlations fail to completely omit these effects of spatial structure. Further, the model is falsifiable, since it results in many patterns that can easily be tested in real primates by means of existing data.     

Hierarchy and social status in Budongo chimpanzees

The status hierarchy is fundamental in the lives of male chimpanzees. This study describes the dominance interactions and social status among adult male chimpanzees of the Sonso community in the Budongo Forest Reserve, Uganda, during the period that they were first studied (1994 and 1995). Social dominance is typically measured using the behaviour of either the subordinate or the dominant individual, but a relationship is dependent on the behaviour of both parties and this study explicitly used both subordinate and dominant behaviours to investigate the status hierarchy. Among adult males of the Sonso community, agonistic interactions occurred at a low rate and pant-grunts were rare, but males could be ranked into separate hierarchies of agonistic dominance and pant-grunting (labelled respect) using ratios of behaviour performed/behaviour received. These hierarchies were combined to form a single hierarchy of social status that divided the males among five distinct status levels. The highest status level was held by an alliance between two males who replaced the previous alpha male during the first part of the study. Neither male in this alliance partnership pant-grunted to the other, although the reason for cooperative behaviour was unclear. Although the nominally beta male was treated as such by other adult males, he achieved surprisingly little mating success. Budongo Forest chimpanzees do not warrant the sometimes-expressed view that they are non-aggressive and peaceable and the broad pattern of their status interactions matches with that seen in other chimpanzee populations.     

Honest signalling,dominance hierarchies and body condition in House Sparrows Passer domesticus (Aves: Passeriformes) during acute coccidiosis

Parasitic infections may change the equilibrium between the costs and benefits of an animal for maintaining its status in a social group. Consequently, parasites may influence the social status of an animal in a group. The present study investigated whether acute infection with Isospora spp. has any effect on the social relationships (e.g. dominance hierarchy) of male house sparrows and how the infection influences their behaviour, immune status, and body condition. Furthermore, the study allowed us to examine how important the ‘badge of dominance’ is with respect to maintaining social status even when the actual condition is changing as a result of infection. The results obtained showed that an acute infection leads to changes in the dominance hierarchy of a social group and that body mass losses of birds depend on the achieved hierarchy status. A positive correlation between the badge size and male aggressiveness was only found during acute infection. In addition, we also found a relationship between cell‐mediated immune response and male aggressiveness during acute infection. This suggests that male badge size is not sufficient to maintain a given dominance position. On the other hand, badge size, a signal developed during the moult, appears to remain an informative and ‘honest’ signal several months later, reflecting the energy reserves of a bird faced with a demanding stressful situation such as acute infection. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 718–726.     

A fresh look at the wolf-pack theory of companion-animal dog social behavior

A popular perspective on the social behavior of dogs in multiple-dog households sees the dogs' behavior as reflecting the sociobiological laws of the rigidly structured dominance hierarchy that has been described for wolf packs. This view suggests that aggression problems among dogs are natural expressions of conflict that arise whenever dominance status is in contention. One recommended solution has been for the owner to endorse and enforce a particular dominance hierarchy because, on the wolf pack model, aggression is minimized when the structure of the hierarchy is clear, strong, and stable. This article questions the validity of this perspective on 2 principal grounds. First, because it does not seem to occur in the wild, this article suggests the strong dominance hierarchy that has been described for wolves may be a by-product of captivity. If true, it implies that social behavior—even in wolves—may be a product more of environmental circumstances and contingencies than an instinctive directive. Second, because feral dogs do not exhibit the classic wolf-pack structure, the validity of the canid, social dominance hierarchy again comes into question. This article suggests that behavioral learning theory offers another perspective regarding the behavior of dogs and wolves in the wild or in captivity and offers an effective intervention for aggression problems.     

Social hierarchy in the domestic goat: effect on food habits and production

Outside the scientific world, the effect of social behaviour on production is little taken into account, but the importance of this relationship has been sufficiently proven in some animal species. Nevertheless, there are scarce works that emphasise the importance of behaviour in the production of the goat. The main objective of this paper is to determine if there is a stable hierarchy of dominance in a flock of goats fed in pasture, and if this hierarchy influences somehow the diet selected in the pasture and in its production of milk and meat. The study was carried out in a flock of goats in semi-extensive grazing management. The interactions observed in the pasture during the supplementary feeding and during the milking were written down. This allowed us to determine the dominance rank. The diet was determined in the pasture by the direct observation method. The production of milk was measured daily. The meat production consisted on the weight of the kids in their first day of life and after a month. Among the most prominent results, the following should be indicated: (a) Within the herd, a clearly established, quite stable and linear hierarchic order exists. (b) The most aggressive animals are those that occupy the highest positions within the social hierarchy. (c) Age, large size and horns seem to be the physical factors that most favor dominance. (d) When more forage becomes available, differences appear in the diet chosen by dominant and subordinate animals, that is, they become more selective. In the months of greater shortage, these differences in feeding disappear, and they become more generalist. (e) The production of animals is affected by dominance. However, contrary to what might otherwise be thought, it is the middle range of goats that are the most productive.     

Dominance in Domestic Dogs: A Quantitative Analysis of Its Behavioural Measures

A dominance hierarchy is an important feature of the social organisation of group living animals. Although formal and/or agonistic dominance has been found in captive wolves and free-ranging dogs, applicability of the dominance concept in domestic dogs is highly debated, and quantitative data are scarce. Therefore, we investigated 7 body postures and 24 behaviours in a group of domestic dogs for their suitability as formal status indicators. The results showed that high posture, displayed in most dyadic relationships, and muzzle bite, displayed exclusively by the highest ranking dogs, qualified best as formal dominance indicators. The best formal submission indicator was body tail wag, covering most relationships, and two low postures, covering two-thirds of the relationships. In addition, both mouth lick, as included in Schenkel’s active submission, and pass under head qualified as formal submission indicators but were shown almost exclusively towards the highest ranking dogs. Furthermore, a status assessment based on changes in posture displays, i.e., lowering of posture (LoP) into half-low, low, low-on-back or on-back, was the best status indicator for most relationships as it showed good coverage (91% of the dyads), a nearly linear hierarchy (h’ = 0.94, p<0.003) and strong unidirectionality (DCI = 0.97). The associated steepness of 0.79 (p<0.0001) indicated a tolerant dominance style for this dog group. No significant correlations of rank with age or weight were found. Strong co-variation between LoP, high posture, and body tail wag justified the use of dominance as an intervening variable. Our results are in line with previous findings for captive wolves and free-ranging dogs, for formal dominance with strong linearity based on submission but not aggression. They indicate that the ethogram for dogs is best redefined by distinguishing body postures from behavioural activities. A good insight into dominance hierarchies and its indicators will be helpful in properly interpreting dog-dog relationships and diagnosing problem behaviour in dogs.     

黄山短尾猴不同顺位等级雄性个体友好行为的比较研究

社会顺位等级制度在灵长类动物中普遍存在,它对动物个体的繁殖和社会行为有广泛的影响.本研究对黄山短尾猴鱼鳞坑YA2群6个不同顺位成年雄性个体,根据顺位高低,将它们分成3组:高顺位组(2只个体)、中等顺位组(2只个体)、低顺位组(2只个体),采用目标动物取样法对它们的社会行为进行研究,结果表明,3组之间(1)接收和发出架桥行为频次差异显著,高顺位组接收架桥次数最多;(2)接收和发出爬跨行为频次差异显著;低顺位组接收爬跨次数最多;(3)发出呈臀行为频次差异显著,但接收呈臀行为频次差异不显著;高顺位组是接收呈臀次数最多,低顺位组发出呈臀次数最多;(4)摇树行为频次差异显著,高顺位组发出摇树行为最多.因此雄性黄山短尾猴友好行为可以体现出社群顺位等级关系,这种社群顺位等级关系和这些友好行为在维持社群稳定上有重要作用.     

The effects of dominance on leadership and energetic gain: a dynamic game between pairs of social foragers

Although social behaviour can bring many benefits to an individual, there are also costs that may be incurred whenever the members of a social group interact. The formation of dominance hierarchies could offer a means of reducing some of the costs of social interaction, but individuals within the hierarchy may end up paying differing costs dependent upon their position within the hierarchy. These differing interaction costs may therefore influence the behaviour of the group, as subordinate individuals may experience very different benefits and costs to dominants when the group is conducting a given behaviour. Here, a state-dependent dynamic game is described which considers a pair of social foragers where there is a set dominance relationship within the pair. The model considers the case where the subordinate member of the pair pays an interference cost when it and the dominant individual conduct specific pairs of behaviours together. The model demonstrates that if the subordinate individual pays these energetic costs when it interacts with the dominant individual, this has effects upon the behaviour of both subordinate and the dominant individuals. Including interaction costs increases the amount of foraging behaviour both individuals conduct, with the behaviour of the pair being driven by the subordinate individual. The subordinate will tend to be the lighter individual for longer periods of time when interaction costs are imposed. This supports earlier suggestions that lighter individuals should act as the decision-maker within the pair, giving leadership-like behaviours that are based upon energetic state. Pre-existing properties of individuals such as their dominance will be less important for determining which individual makes the decisions for the pair. This suggests that, even with strict behavioural hierarchies, identifying which individual is the dominant one is not sufficient for identifying which one is the leader.     

Dominance hierarchy among workers changes with colony development in Polistes japonicus (Hymenoptera, Vespidae) paper wasp colonies with a small number of workers

Dominance hierarchy in the primitively eusocial wasp Polistes japonicus was analysed in four colonies for two periods: (1) the first-brood period, when only early emerging workers are present on the nest, and (2) the mixed-brood period, when the first and second (last) broods are present on the nest. The rank in the dominance hierarchy was determined based on a sociogram showing a dominance–subordinance relationship for all pairs of workers. During the first-brood period, older workers were likely to be more dominant (older dominance hierarchy), while the rank of workers was reversed during the mixed-brood period, with younger workers being likely to be more dominant (younger dominance hierarchy). However, the oldest and youngest workers were not always the top-ranked workers in the dominance hierarchy during the first- and mixed-brood periods, respectively, and during the mixed-brood period no younger dominance hierarchy was evident when the first or second brood was analysed separately. Higher ranked workers displayed dominance behaviour more frequently, and the lowest ranked worker hardly displayed dominance behaviour. Most workers displayed dominance behaviours primarily towards the worker ranked immediately below in the dominance hierarchy during the mixed-brood period but not during the first-brood period. The bodies of younger workers were larger for the mixed brood, but not for the first brood in some colonies or the second brood in all colonies. The association between body size and rank in the dominance hierarchy was negative during the first-brood period and positive during the mixed-brood period, with a nearly significant trend also seen even when the analysis was limited to the second brood. To explain the above temporal change from an older dominance hierarchy to a younger dominance hierarchy, we propose the hypothesis that the probability of a worker inheriting the colony increases rapidly with colony development, and consequently younger larger workers attempt to move up the dominance hierarchy in order to produce their own offspring by becoming the superseder late in colony development, rather than working harmoniously so as to boost the overall production of reproductive progeny for a colony, which is the strategy adopted early in colony development.     

成年黄山短尾猴雌性等级结构稳定性

等级结构稳定性是衡量群体凝聚力的重要指标,雌性等级结构稳定对于母系社会群体具有重要的生物学意义。本文采用目标动物取样和全事件记录相结合的方法,研究黄山短尾猴鱼鳞坑A1 群(YA1 群)和鱼鳞坑A2 群(YA2 群)的成年雌性分别在交配季节(2011 年9 ～ 12 月)和非交配季节(2012 年2 ～ 5 月)内的攻击-屈服行为。采用等级结构中雌性间攻击- 屈服频率、社会顺位和等级梯度3 个量化指标,首次定量探讨了短尾猴雌性等级结构及其稳定性。研究期间,YA1 群和YA2 群雌性间攻击- 屈服频率、社会顺位和等级梯度均无季节性变化(P >0. 05)。结果表征短尾猴雌性等级结构趋于稳定,该结果支持了短尾猴雌性等级结构稳定性的定性判断。     

A Novel Method of Assessing Dominance Hierarchies Shows Nuance,Linearity and Stability in the Dinosaur Ant Dinoponera quadriceps

Many social species with relatively simple societies have dominance hierarchies of individuals, with dominant individuals achieving fitness and subordinate individuals either queuing to obtain fitness or achieving only indirect fitness by helping relatives. Assessing the dominance hierarchy in a social group is generally based upon observing dyadic interactions as and when they occur spontaneously within the whole‐group setting. However, this method can be very time‐consuming because many dyads interact only very rarely, necessitating either extremely long observation periods or many dyadic relationships being unresolved. Here, we report an alternative method using the queenless dinosaur ant Dinoponera quadriceps, which lives in colonies containing tens of individuals. We removed all individuals from their nest and observed the dominance behaviours expressed in isolated dyadic interactions for every pairwise combination of individuals. Individuals showed a classic dominance behaviour in this setting, and the rapid nature of the assay allowed us to observe every dyadic relationship on a weekly basis over 4 weeks. The dominance hierarchies based on these isolated dyadic interactions correlated well with those produced by the conventional method of colony observations. They showed the hierarchies to be highly linear and stable, and also revealed that dominance relationships may extend further down the hierarchy than previously thought. Although highly manipulative, the isolated dyadic interaction method works well and will likely make more feasible the study of other social species in which pairs of individuals can be isolated together.     

Behaviour of the Indian social wasp Ropalidia cyathiformis on a nest of separate combs (Hymenoptera: Vespidae)

Observations were made on a nest of Ropalidia cyathiformis consisting of three combs. The number of eggs, larvae, pupae and adults were monitored at about 3-day intervals for a 2-month period. The behaviour of the adults was observed with special reference to the proportion of time spent on each of the three combs, the proportion of time spent away from the nest site and the frequencies of dominance interactions and egg laying. The adults moved freely between the three combs suggesting that all of them and all the three combs belonged to one nest. However, most of the adults preferred combs 2 and 3 over comb 1. Of the 10 animals chosen for a detailed analysis of behaviour, seven spent varying periods of time away from the nest site and oRen brought back food or building material. Five of the 10 animals laid at least one egg each but two adults monopolized most of the egg-laying. The animals showed a variety of dominance interactions on the basis of which they have been arranged in a dominance hierarchy. The dominant individuals laid most of the eggs and spent little or no time foraging, while the subordinate individuals spent more time foraging and laid few eggs or none. It is argued that R. cyathiformis is different from R. marginata , the only other Indian social wasp whose behaviour has been studied, in being at a more primitive stage of social organization.     

Testosterone and Linear Social Dominance Status in Captive Male Dabbling Ducks in Winter

Dominance hierarchies play an important role in avoidance and/or solving conflicts in gregarious species. In dabbling ducks (Anas species), dominance allows for feeding‐site monopolization in winter quarters where resources are generally limited. In addition, male social rank should theoretically favour access to mates. Dominance rank can be associated with morphological traits, and is often correlated with aggressiveness, a behavioural trait generally related to high testosterone levels. In this study, we investigated the existence of a winter group structure based on dominance relationships and tested for a linear hierarchy, in three species of captive male dabbling ducks (mallard Anas platyrhynchos, pintail A. acuta and wigeon A. penelope). We then analysed the relationship between dominance ranks, morphological parameters and testosterone levels measured in early (Oct.) and mid‐winter (Dec./Jan.). We found that the three male groups of the three species exhibited a linear hierarchy. Testosterone levels differed during winter and between species. Morphologic measurements, body mass and body condition were not correlated with individual dominance ranks, whereas dominant males had higher testosterone levels than subordinates. The slopes of the relationships were similar between species and winter period, but the y‐intercepts differed between species and between early and mid‐winter phases. The linear hierarchy found in the three species indicates that dominance relationships strongly structure dabbling duck groups in winter. Lack of correlation between rank and morphological characters, but correlation of rank with testosterone levels suggests that social rank is more dependent on behavioural traits such as aggressive behaviour. The differences between species and winter periods are discussed in relation to migration and wintering phenology.     

On dominance relations and the structure of animal societies: II. Some effects of possible social factors

In a previous paper (Landau, 1951) it was shown that a society with a dominance relation would rarely tend to be close to the hierarchy in structure if dominance is determined solely by the inherent characteristics of the members. Here we consider the effects of other factors, due to social rank or to the outcome of previous encounters which affected dominance. The following results are obtained. A uniform bias against reversal of dominance will have no effect on the stationary distribution of the structure of the society. If the probability of dominance is a linear function of the previously established score (number of members dominated), there will be a small tendency for the society to move toward the hierarchy; but this is negligible for large societies. If a member never challenges another whose score exceeds his own by two or more, or if he can never dominate if he should challenge, then the hierarchy is the only stable structure. From the last result it is concluded that social factors which restrict challenges or the probability of dominance could easily account for societies close to the hierarchy, such as are observed in flocks of domestic hens. The effectiveness of social bias in establishing hierarchies is much greater in small societies than in large ones.     

Hierarchy,kinship and social interaction among Japanese monkeys (Macaca fuscata)

The study reports the relationship between hierarchy, genetic relatedness and social interaction in captive Japanese macaques. Grooming and proximity were found to be positively related to both dominance rank and degrees of relatedness. Ranks also positively correlated with threats while no relationship was observed between genetic relationships and agonistic interactions. The removal of a-male tightened the male hierarchy while the female hierarchy became relatively loose. Affiliative behaviour became more correlated with ranks than degrees of genetic relatedness. In the absence of α-male, the next dominant male avoided involvement in either agonistic or afliliative interactions with reintroduced animals and group females.     

Establishment of a free-ranging colony of stumptail macaques (Macaca arctoides): Social relations I

Data on the social behaviour of a free-ranging troop of Stumptail macaques are reported for a period starting of August 15th to November 7th of 1974. Positive interactions take a greater part in the daily life of the troop than negative interactions. Individuals order themselves in an essentially linear dominance hierarchy and offspring rank immediately below their mother. Agonism and displacement are good predictors of dominance rank. Dominant individuals are a strong source of attraction for subordinates and the alpha male is a powerful social magnet for immatures. Grooming was found to be correlated with dominance rank and individuals holding adjacent ranks tend to interact positively with one another. To gain access to dominant females, subordinates direct a great deal of positive behaviour to the female’s youngest offspring. As social distance decreases the selection of a social partner becomes more strict and tends toward adjacency. However, factors such as motherhood, genealogical ties, and special relationships with non adjacent individuals, can override the tendency. The direction and quantity of male-care displayed by the adult male and by juvenile males toward younger individuals was found to be influenced by the troop’s dominance patterns. Sex differences were found to exist in male-care received and a negative association was found with the age of the receiver. Adult females are the main regulators of social relations and their rank and friendships provide their offspring with the social format, before puberty, in which they develop socially. The alpha male is the group protector, the performer of policing, an important element in the immatures’ social development, and a powerful source of attraction for all troop members.