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Dominance hierarchies in domestic horses

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Abstract

Dominance hierarchies were studied in 11 herds of domestic horses and ponies (Equus caballus). A paired feeding test was utilized to establish the dominance—subordination relationship between each pair of animals in a herd. Aggressive actions, threats, bites, kicks and chases were also recorded. In small herds linear hierarchies were formed, but in large herds triangular relationships were observed. Aggression was correlated with dominance rank. Body weight, but not age, appear to affect rank in the equine hierarchy. Juvenile horses were more likely to share feed with each other than were adult horses and were usually subordinate to adult horses. The daughters of a dominant mare were dominant within their own herds.

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... Several studies on horses have noted an association between social status (in terms of dominance or aggression) and physical attributes. These physical attributes have included weight or size (Clutton-Brock et al., 1976;Berger, 1977;Houpt et al., 1978;Rutberg and Greenberg, 1990;Ingólfsdóttir and Sigurjónsdóttir, 2008), height (Rutberg and Greenberg, 1990), age (Keiper, 1988;Rutberg and Greenberg, 1990;Van Dierendonck et al., 1995;Sigurjonsdottir et al., 2003;Heitor et al., 2006;Ingólfsdóttir and Sigurjónsdóttir, 2008) and sex (Houpt and Keiper, 1982). Dominance has also been associated with the amount of time an individual has been resident in the herd (Clutton-Brock et al., 1976;Van Dierendonck et al., 1995). ...
... Whilst previous studies have explored the influence of physical factors upon dominance rank in horses (Houpt et al., 1978;Rutberg and Greenberg, 1990), this has not been considered vice versa, nor the direction of association considered; presumably because many physical attributes such as height and body size do not change much once fully grown, and therefore cannot change in response to a change in rank. Body condition may be more strongly determined by individual behavioural differences and is in this respect very different from size or height. ...
... Several previous authors have suggested that size, weight or height may be an important determinant of dominance (Clutton-Brock et al., 1976;Houpt et al., 1978;Ingólfsdóttir and Sigurjónsdóttir, 2008), presumably because a larger size affords a greater competitive advantage in a resource conflict situation (Maynard-Smith and Brown, 1986). Height was not associated with dominance rank in this study, however height was associated with body condition, where smaller individuals generally had a higher body condition score. ...
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The aim of our study was to explore the association between dominance rank and body condition in outdoor group-living domestic horses, Equus caballus. Social interactions were recorded using a video camera during a feeding test, applied to 203 horses in 42 herds. Dominance rank was assigned to 194 individuals. The outcome variable body condition score (BCS) was recorded using a 9-point scale. The variables age and height were recorded and considered as potential confounders or effect modifiers. Results were analysed using multivariable linear and logistic regression techniques, controlling for herd group as a random effect. More dominant (p = 0.001) individuals generally had a higher body condition score (p = 0.001) and this association was entirely independent of age and height. In addition, a greater proportion of dominant individuals fell into the obese category (BCS ≥ 7/9, p = 0.005). There were more displacement encounters and a greater level of interactivity in herds that had less variation in age and height, lending strength to the hypothesis that phenotypic variation may aid cohesion in group-living species. In addition there was a strong quadratic relationship between age and dominance rank (p < 0.001), where middle-aged individuals were most likely to be dominant. These results are the first to link behavioural predictors to body condition and obesity status in horses and should prompt the future consideration of behavioural and social factors when evaluating clinical disease risk in group-living animals.
... Age is not significant in domestic horses and where paired feeding tests are used to determine rank hierarchy (e.g. Houpt et al., 1978). Other determinants identified in wild and semi-wild horses and Przewalski horses include maternal rank, in Camargue horses and Assateague ponies, Icelandic Ponies and Jeju ponies (Feh, 1990;Rutberg and Greenberg, 1990;VanDierendonck et al., 1995;Rho et al., 2004) (which was also identified in domestic groups Houpt et al., 1978), and longevity of band membership (VanDierendonck et al., 1995;Monard and Duncan, 1996). ...
... Houpt et al., 1978). Other determinants identified in wild and semi-wild horses and Przewalski horses include maternal rank, in Camargue horses and Assateague ponies, Icelandic Ponies and Jeju ponies (Feh, 1990;Rutberg and Greenberg, 1990;VanDierendonck et al., 1995;Rho et al., 2004) (which was also identified in domestic groups Houpt et al., 1978), and longevity of band membership (VanDierendonck et al., 1995;Monard and Duncan, 1996). Social experience and individual temperament were identified as significant in a bachelor herd of Przewalski horses (Tilson et al., 1988) and as was aggression in domestic mares (Houpt et al., 1978) and draft breed foals (Araba and Crowell-Davis, 1994). ...
... Other determinants identified in wild and semi-wild horses and Przewalski horses include maternal rank, in Camargue horses and Assateague ponies, Icelandic Ponies and Jeju ponies (Feh, 1990;Rutberg and Greenberg, 1990;VanDierendonck et al., 1995;Rho et al., 2004) (which was also identified in domestic groups Houpt et al., 1978), and longevity of band membership (VanDierendonck et al., 1995;Monard and Duncan, 1996). Social experience and individual temperament were identified as significant in a bachelor herd of Przewalski horses (Tilson et al., 1988) and as was aggression in domestic mares (Houpt et al., 1978) and draft breed foals (Araba and Crowell-Davis, 1994). Mares or stallions may hold the apex position in groups. ...
... Lloyd and Rasa (1989) found that dominant mountain zebra females were older than the others in their group. Furthermore, there have been only a few horse researchers who have not found any positive correlation between the age of a mare and her social rank (Berger, 1977;Houpt et al., 1978;Haag et al., 1980). Other researchers, using a different herd of horses, found that no clustering of pregnant mares near the top or the bottom of the hierarchy occurred. ...
... Other researchers, using a different herd of horses, found that no clustering of pregnant mares near the top or the bottom of the hierarchy occurred. However, these same mares were not tested when they were not pregnant (Houpt et al., 1978). Further, it has been observed that wild females of the Hartmann zebra (E. ...
... We did not find any evidence for a possible effect of pregnancy on dominance ranking. This same result has been reported for both wild Hartmann mountain zebra and horses (Joubert, 1972;Berger, 1977;Houpt et al., 1978). On the other hand, other researchers, such as Houpt et al. (1978), have suggested that pregnancy could influence the rank of domestic horse mares. ...
Article
Plains zebra live in harems that include one to six adult mares. Between these mares is a strong order of social hierarchy. The social rank of an equid mare is typically correlated with her age. Further, high-ranking captive plains zebra mares produce more surviving offspring than low-ranking mares. The objectives of this study were to, first, examined the factors that influence social rank of captive plains zebra mares, and second, test if high-ranking mares conceive earlier and if they have shorter inter-birth intervals than low-ranking ones. We observed three herds of captive plains zebra (a total of 18 mares) at the Dvůr Králové Zoo, Czech Republic. During the 831 h of observation, we recorded 1713 aggressive interactions (biting and offensive kicking) between the mares. These data were used to determine, for each mare, the total number of mares that dominated her in each period of social stability. The GLMM model revealed that older mares were dominated by a lower number of mares than the younger mares. We also found that the probability that a mare would conceive declined with the increasing number of dominant mares. Further, we tested the relationship between the number of dominant mares and the inter-birth interval using 29 intervals for 15 mares. These inter-birth intervals were divided into two groups. When a stallion was continuously present in the herd, the intervals lasted from one birth to the next birth (natural intervals). When a herd was without a stallion, the intervals lasted from the release of the stallion into the herd to the birth of foal (stallion-influenced intervals). The analysis revealed that the inter-birth intervals decreased with an increasing number of dominant mares and the natural intervals decreased with an increasing number of offspring successfully reared by a mare. This finding is the first one in equids and contributes to the previous findings that suggest that social status influences reproductive success.
... Rank order in horses has been suggested to be linear, that is, A dominates B, C and D; B dominates C and D, and C dominates D, but triangles can also occur [29,31]. Horses can form strong and long-lasting social bonds where individuals can interfere in dyadic interactions in an attempt to safeguard existing relationships [32][33][34]. ...
... The determination of rank relative to body weight or height, age, or sex is not easily predicted as revealed by contradicting results from different studies. Body weight, for example, has only recently been correlated with high rank [35] and was also found to affect position in the hierarchy in captive herds studied by Houpt et al [31] but not in a study by Van Dierendonck et al [29]. Most results suggest a correlation of age with rank [36,37] which seems appropriate because older horses usually have more experience than younger animals (e.g., in exploiting resources) [38]. ...
Article
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Dominance hierarchies in horses primarily influence priority access to limited resources of any kind, resulting in predictable contest outcomes that potentially minimize aggressive encounters and associated risk of injury. Levels of aggression in group-kept horses under domestic conditions have been reported to be higher than in their feral counterparts but can often be attributed to sub-optimal management. Horse owners often express concerns about the risk of injuries occurring in group-kept horses but these concerns have not been substantiated by empirical investigations. What has not yet been sufficiently addressed are human safety aspects related to approaching and handling group-kept horses. Given horses’ natural tendency to synchronize activity to promote group cohesion, questions remain about how group dynamics influence human-horse interactions. Group dynamics influence a variety of management scenarios, ranging from taking a horse out of its social group to the prospect of humans mimicking the horse’s social system by taking a putative leadership role and seeking after an alpha position in the dominance hierarchy to achieve compliance. Yet, there is considerable debate about whether the roles horses attain in their social group are of any relevance in their reactions to humans. This article reviews the empirical data on social dynamics in horses, focusing on dominance and leadership theories and the merits of incorporating those concepts into the human-horse context. This will provide a constructive framework for informed debate and valuable guidance for owners managing group-kept horses and for optimizing human-horse interactions.
... However, recent research shows that horses live in complex social environments which might favour the evolution of social transfer of information (Nicol 2002, Murphy andArkins 2007). Horses form largely stable harems and bachelor groups with clear linear hierarchies (Houpt et al. 1978), and preferentially interact with up to three partners (Tyler 1972). Social groups may temporarily split or merge (Linklater 2000) thus showing a fission-fusion dynamic. ...
... With only one exception, all learners which manipulated the rope with their hoof returned to using the mouth or a mixed hoof-mouth technique after further observation in horses, age usually correlates with rank. Most young horses start at the bottom of their group's social hierarchy and rise in rank as they grow older (Houpt et al. 1978). Additionally, young horses were shown to be more exploratory in the non-social novel object test conducted here, and in other studies (Vidament 2012). ...
Article
Social learning is said to meet the demands of complex environments in which individuals compete over resources and cooperate to share resources. Horses (Equus caballus) were thought to lack social learning skills because they feed on homogenously distributed resources with few reasons for conflict. However, the horse's social environment is complex, which raises the possibility that its capacity for social transfer of feeding behaviour has been underestimated. We conducted a social learning experiment using 30 socially kept horses of different ages. Five horses, one from each group, were chosen as demonstrators, and the remaining 25 horses were designated observers. Observers from each group were allowed to watch their group demonstrator opening a feeding apparatus. We found that young, low-ranking and more exploratory horses learned by observing older members of their own group, and the older the horse, the more slowly it appeared to learn. Social learning may be an adaptive specialisation to the social environment. Older animals may avoid the potential costs of acquiring complex and potentially disadvantageous feeding behaviours from younger group members. We argue that horses show social learning in the context of their social ecology and that research procedures must take such contexts into account. Misconceptions about the horse's sociality may have hampered earlier studies.
... affiliative relationships) may be expected to initiate more movements than less bonded individuals, partly because bonded females have been shown to protect each other's offspring (Cameron et al., 2009) and may therefore also move together to remain in close proximity. Furthermore, because horses usually have a linear dominance hierarchy (Houpt et al., 1978), social rank may also affect the degree to which horses are followed when they depart from the group (Tyler, 1972;Heitor et al., 2006). ...
... Similar to findings in Canada geese (Raveling, 1969) and barheaded geese (Black, 1988) the departure of immature horses (between 1 and 3 years of age) very rarely initiated movement by others. This may be because of their youth, and consequently low rank, as age and rank are correlated in most horse groups (Houpt et al., 1978;Keiper and Sambraus, 1986;Linklater et al., 1999). It may be that young subordinates follow the movements of older, more dominant horses to benefit from their greater experience, as has been shown in elephants, primates and dolphins (King et al., 2008;Lusseau and Conradt, 2009;McComb et al., 2011). ...
Article
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Herds of ungulates, flocks of birds, swarms of insects and schools of fish move in coordinated groups. Computer models show that only one or very few animals are needed to initiate and direct movement. To investigate initiation mechanisms further, we studied two ways in which movement can be initiated in feral horses: herding, and departure from the group. We examined traits affecting the likelihood of a horse initiating movement i.e. social rank, affiliative relationships, spatial position, and social network. We also investigated whether group members join a movement in dominance rank order. Our results show that whereas herding is exclusive to alpha males, any group member may initiate movement by departure. Social bonds, the number of animals interacted with, and the spatial position were not significantly associated with movement initiation. We did not find movement initiation by departure to be exclusive to any type of individual. Instead we find evidence for a limited form of distributed leadership, with higher ranking animals being followed more often.
... The studies on the effects of the age in hierarchy acquaintance have provided inconsistent results in horse studies. It remains unclear whether older horses always dominate the younger or, most likely, more factors play a role together (Tyler, 1972;Clutton-Brock et al., 1976;Berger, 1977;Houpt et al., 1978;Wells and von Goldschmidt-Rothschild, 1979;Haag et al., 1980;Rubenstein, 1981;Keiper and Sambraus, 1986;Ellard and Crowell-Davis, 1989;Araba and Crowell-Davis, 1994;Weeks et al., 2000;Heitor and Vicente, 2008). The mothers may influence the age and rank of their offspring within the foals born in the same year through timing the delivery; they produce larger offspring with greater fecundity and a higher rank compared to their herdmates born later in the year when giving birth earlier in the season ( Wells and von GoldschmidtRothschild, 1979;Green and Rothstein, 1993). ...
... Alternatively, the mother may preferentially direct aggressive behavior towards the offspring of lower-ranking herdmates (Horrocks and Hunte, 1983;Weeks et al., 2000). Associative learning of the animals involved in these interactions may result in later differences in their position within the hierarchy (Houpt et al., 1978). However, we haven't found evidence of direct maternal rank inheritance in our study. ...
Article
We present a study focused on those factors influencing dominance position in young horses, with emphasis on the role of the mother. Horses, as other group-living polygynous mammals, form stable linear dominance hierarchies based on agonistic interactions. Higher dominance positions are believed to be connected, in both sexes, to better condition and higher reproductive success. Many variables play a role in forming the dominant-submissive relationships between horses; however, the maternal effect upon the dominance position of the offspring still remains unclear, as do the possible mechanisms of transference ("inheritance"). We hypothesized that the maternal dominance position, plus differences in suckling parameters or maternal style, may be responsible for later outcome of the offspring's dominance position, characterized by two variables: index of fighting success (CB); and rate of winning encounters (RW). Our study animals were 8 groups of Kladruby horses, loose-housed lactating mares with foals (n = 66 mare-foal pairs); and subsequently four groups of the same foals at 3 years of age. Our results revealed the impact of age on the dominance position of the young horses (P < 0.001 for CB, and P < 0.01 for RW), and residence in the group (P < 0.01, P < 0.01, respectively); not the maternal dominance position. Older foals reached higher dominance positions, independent of the dominance position, age, or experience of the mother; therefore, we did not find support for direct inheritance of maternal rank. Nevertheless, the foals born to the same mare in two consecutive seasons (n = 16 mares) revealed fair repeatability in the dominance position they obtained at three years of age (intraclass correlation coefficient = 0.46). This suggests an important constant effect of the mother on the social success of her progeny; however, we did not find a significant effect of any of the tested variables describing maternal characteristics or maternal care. Dominance position depended significantly on the foal's age at observation, and the residence in the herd formed via sequential introducing of later-weaned groups of foals. The most dominant horses were mainly recruited from the first-weaned group of the season, and thus were also the oldest individuals in the herd. Further research is needed to discover the role of foal personality and mare style, and their links to possible dominance behaviors in a herd.
... Studies of these feral populations may potentially provide valuable insights into behavioral and physiologic data obtained from mares maintained under more restrictive domestic management regimes. Within groups, stable linear dominance hierarchies are established among mares in both single and mixed sex groupings (Clutton-Brock et al., 1976;Houpt et al., 1978;Sigurjonsdottir et al., 2003). Mare rank within a group is determined by a range of factors such as size, age, and length of residence within the group that have been found to be consistently predictive of high rank (van Dierendonck et al., 1995;Sigurjonsdottir et al., 2003;Rho et al., 2004). ...
... These are not always independent as older mares will tend to be larger than juveniles and where they are living in stable groups the oldest will tend to have had the longest residence time making it difficult to distinguish between the specific effects of age and residence time. The importance of other possible factors such as pregnancy, foaling, or lactation status has been shown to be more variable between different populations (Berger, 1977;Houpt et al., 1978;Estep et al., 1993). Hierarchical position is maintained partially by the outcomes of aggressive encounters involving chasing and physical shoving, threats to bite or kick, and ultimately actual kicking and biting (Houpt and Keiper, 1982). ...
Article
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Among horse owners “mare-ishness” is easily recognized, if poorly defined, as generally awkward or recalcitrant behavior. In common with other mammals, however, horses do show a range of female-specific behavior patterns concerned particularly with sexual and maternal functions but also encompassing aspects of social peer interaction. Many of these behavior patterns are observed more easily in free living feral populations and are repressed at least partially under standard domestic management regimes. Feral horses form small stable breeding groups within which mares create linear dominance hierarchies based on the outcomes of aggressive encounters and positive social bonding. Rank within the social hierarchy may also influence reproductive success, with dominant mares having shorter foaling intervals and earlier foaling than lower ranking subordinate mares. Advantageous early foaling may reflect preferential mating by the group stallion based either simply on enhanced physical condition leading to earlier reproductive cycling in dominant mares or on an increased attractiveness to dominant mares by the stallion contingent on some aspect of dominance characteristics. The endocrine axis responsible for regulation of sexual behavior in the mare shows a degree of commonality with systems underlying social dominance. Both these behavior patterns are driven by a complex interaction of endocrine and neuro-endocrine factors sensitive to physical and social environmental cues and in feral free-living horses these are interlinked to an extent that may be under appreciated in domestic breeding populations.
... Aggressiveness has been positively correlated to dominance rank (Tyler, 1972;Clutton-Brock et al., 1976;Houpt et al., 1978;Houpt and Wolski, 1980;Weeks et al., 2000;Heitor et al., 2006a). However, because of the many reported ways to calculate dominance rank and the lack of a standard, our study calculated only the ranks of relative aggressiveness and compared those results to the extant literature on dominance hierarchies, based on this correlation between aggressiveness and dominance rank. ...
... Age had no effect on agonistic rate as an actor or on the subcategories. Houpt et al. (1978) and York and Schulte (2014) also found no correlation between dominance and age. However, in other studies, dominance rank correlated positively with age (Clutton-Brock et al., 1976;Keiper and Sambraus, 1986;Van Dierendonck et al., 1995;Sigurjonsdottir et al., 2003;Rho et al., 2004;Van Dierendonck et al., 2004;Heitor et al., 2006a;Heitor and Vicente, 2010). ...
Article
Group housing provides horses with social contact, a lack of which is associated with health and behavior problems. Despite the benefits of group housing for horses, horse owners are concerned about aggression and resulting injuries. This study focused on agonistic and affiliative interactions in a focal group of (originally) 12 horses with short and longer term changes in composition, variation in available area and presence of peri-parturient mares. Age and density had no significant effect on agonistic or affiliative behavior. However, when agonistic behavior was considered within three subcategories, density did have a significant positive effect on contact and threat aggression, but not on passive aggression (avoid and displace). When analyzing only the days without the most aggressive horse, age and density had a positive effect on agonistic interactions, and density had a negative effect on affiliative interactions. Days with and without the most aggressive horse showed no significant overall differences in either category of social interactions. Agonistic and affiliative interactions were not significantly correlated, but agonistic interactions had a significant linear and quadratic effect on affiliative interactions. Relative level of aggressiveness was used instead of a formal measure of dominance rank as aggression level is the main issue for horse owners. Comparing interactions with more and less aggressive horses, there was no overall effect for affiliative interactions. However, overall, horses in the focal group were on average 3.7 times more aggressive towards less aggressive horses, compared to more aggressive horses. Relationships between agonistic and affiliative interactions, density, age and the role of relative aggressiveness are complicated and more research is needed to clarify the most relevant factors under particular sets of circumstances and their contribution to intraspecific aggression in various contexts.
... Stallions also expressed no difference in frequency of agonistic behaviors toward control and treated females. This is not surprising since agonistic expressions within feral horse bands are often expressed between females in order to establish and facilitate dominance (Houpt et al., 1978; Waring, 1983; Keiper and Receveur, 1992; Weeks et al., 2000). The stallion is generally not the most dominant member of the band, perhaps as a result of greater time spent away from the group while defending or recruiting females (Keiper and Receveur, 1992). ...
Article
Managers concerned with shrinking habitats and limited resources for wildlife seek effective tools for limiting population growth in some species. Fertility control is one such tool, yet little is known about its impacts on the behavioral ecology of wild, free-roaming animals. We investigated influences of the immunocontraceptive porcine zona pellucida (PZP) on individual and social behavior in bands of feral horses (Equus caballus) in three discrete populations and used 14 hierarchical mixed effect models to gain insight into the influences of PZP treatment on feral horse behavior. A model of body condition was the strongest predictor of feeding, resting, maintenance, and social behaviors, with treated females allocating their time similarly to control females. Time spent feeding declined 11.4% from low condition to high condition females (F1,154 = 26.427, P < 0.001) and was partially reciprocated by a 6.0% increase in resting (F1,154 = 7.629, P = 0.006), 0.9% increase in maintenance (F1,154 = 7.028, P = 0.009), and 1.8% increase in social behavior (F1,154 = 15.064, P < 0.001). There was no difference detected in body condition of treated versus control females (F1,154 = 0.033, P = 0.856), but females with a dependent foal had lower body condition than those without a foal (F1,154 = 4.512, P = 0.038). Herding behavior was best explained by a model of treatment and the interaction of band fidelity and foal presence (AICc weight = 0.660) which estimated no difference in rate of herding behavior directed toward control versus treated females (F1,102 = 0.196, P = 0.659), but resident females without a dependent foal were herded 50.9% more than resident females with a foal (F3,102 = 8.269, P < 0.001). Treated females received 54.5% more reproductive behaviors from stallions than control mares (F1,105 = 5.155, P = 0.025), with the model containing only treatment being the most-supported (AICc weight = 0.530). Treated and control females received harem-tending behaviors from stallions equally (F1,105 = 0.001, P = 0.969) and agonistic behaviors from stallions equally (F1,105 < 0.001, P = 0.986). Direct effects of PZP treatment on the behavior of feral horses appear to be limited primarily to reproductive behaviors and most other differences detected were attributed to the effects of body condition, band fidelity, or foal presence. PZP is a promising alternative to traditional hormone-based contraceptives and appears to contribute few short-term behavioral modifications in feral horses.
... This supports other studies which suggest linear hierarchies to be common in bachelor groups of horses [68,37,3,21]. Especially for small groups, with up to 9 horses, strong linear hierarchies were reported [69]. The inconsistency in the hierarchy of the present group may be caused by the fact that 4 of the 5 stallions were immature and at almost similar age. ...
Article
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The maintenance and development of conservation areas by grazing of large herbivores, such as Przewalski's horses is common practice. Several nature conservation areas house male bachelor groups of this species. When males are needed for breeding they are removed from the groups, often without considering group compositions and individual social positions. However, alpha animals are needed for ensuring group stability and decision making in potentially dangerous situations in several species. To investigate the role of the alpha male in a bachelor group, we observed the behaviour of five Przewalski's horse males during the enlargement of their enclosure. We analyzed the group's social structure and movement orders, as well as the animals' connectedness, activity budgets, and whether they moved with preferred group members and how factors such as social rank influenced the horses' behaviour. We also investigated the excretion of glucocorticoid metabolites (GCM) via faeces of the horses while exploring a new area as a parameter of glucocorticoid production. Our results show that the alpha male is important for a bachelor group in changing environmental conditions. The alpha male had the highest level of connectedness within the group. When exploring the new environment, its position in the group changed from previously being the last to being the first. Furthermore the whole group behaviour changed when exploring the new area. The stallions showed reduced resting behavior, increased feeding and did not stay close to each other. We found that the excretion of glucocorticoid metabolites of most horses rose only marginally during the first days on the new area while only the alpha male showed a significant increased amount of glucocorticoid production during the first day of the enclosure enlargement.
... Social behaviour of the horse has developed to reduce conflict within the group and promote stability and safety as living in groups may have evolved in part to reduce predation pressure on individuals (Rubenstein, 1994;Goodwin, 1999). Individual dominance order is unidirectional, but may not be linear throughout the group as oestrous stages shift in females and offspring mature (Houpt et al., 1978). Despite provisioning and care by humans, domestic horses also form stable hierarchies, which determine access to resources that may be limited at times (Berger, 1977;Rubenstein, 1994). ...
Article
Maintaining a dominant position in a hierarchy requires energetically expensive aggressive displays and physical exertion. Lab based winner-loser studies, often conducted with individuals from non-social species, have shown that subordinates have higher stress hormone levels than dominant individuals. However, in wild studies on cooperative breeders, displays of aggression used to maintain dominance status are associated with elevated stress hormone levels. The effect of reproductive state on dominance and stress has not been addressed within either of these situations. The purpose of this study was to examine physiological stress levels in relation to dominance rank and reproductive state in a non-cooperative breeder and herbivore, the domestic horse. The social interactions and measured faecal glucocorticoids were recorded in pastured, female horses that were either lactating or non-lactating. While faecal glucocorticoid metabolite level did not differ between reproductive state and rank, activity behaviour demonstrated significant differences between reproductive states. Higher energetic requirements of lactation were reflected in significantly longer bouts of eating and significantly less time spent alert and socializing. As non-cooperative breeders, the social nature of horses does not limit their reproduction or resource acquisition based upon rank, and therefore does not fit with the dominance-stress hypothesis or subordinate-stress hypothesis and instead supports a rank- independent stress hypothesis.
... Group size affects the intensity of agonistic interactions and the type and stability of the social structure. Small groups tend to have linear ranks and are more stable than bigger groups [9], since aggressiveness increases with group size, because the availability of resources per individual declines [10]. Individual traits, such as sex, size, and age, are instrumental in the outcome of social interactions and group structure [11,12]. ...
Article
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Agonistic behavioural interactions play a decisive role in the competition for food, space, mating opportunities, and establishing social rank. We used pelt biting (number of bites on an animal’s body) as a proxy for assessing the intensity of agonistic animal interactions and how it responded to social, population, and heat stress factors. We modelled a 14-year time series of pelt biting records and observational data of agonistic interactions on a population of captive Iberian red deer (Cervus elaphus). We found that (i) the higher the social rank of deer, the lower the number of pelt bites received; (ii) increasing heat stress conditions caused deer to suffer more pelt bites; (iii) males received more bites than females; (iv) the heavier the deer, the lower the number of bites on their bodies; (v) the bigger the group, the more bites exhibited on its members; (vi) deer 5–6 years old suffered greater rate of pelt biting than younger or older deer; and (vii) hinds that gave birth earlier in the parturition period suffered less pelt biting than those that gave birth around the peak of the parturition season (p < 0.01 for all effects). Pelt biting is useful to predict management situations in which deer welfare could be at stake.
... After the introduction of foreign adults into homogenous groups of 1-and 2-year-old horses, the number of preferred partners and positive social interactions increased, whereas the number of agonistic interactions decreased (Bourjade et al., 2008). Age is a determining factor in rank (Houpt et al., 1978;Keiper and Sambraus, 1986;van Dierendonck et al., 1995), thus different age classes may contribute to clearer dominance relationships as was hypothesised by Christensen et al. (2002) and Sigurjonsdottir et al. (2003) so potentially minimising overt aggressive interactions. An exception may be the rank position in male horses, as this seems to depend on previous sexual experience (van Dierendonck et al., 1995). ...
Article
Although husbandry conditions for horses have improved over the last decades, many horses are still kept singly with limited or no physical contact to other horses. This is surprising, given the fact that keeping horses in groups is recognised best to fulfil their physical and behavioural needs, especially their need for social contact with conspecifics, as well as to have a beneficial effect on horse–human interactions during training.Group housing of farm animals is widely applied in practice. As a consequence, scientists have investigated numerous aspects of group housing to help further improve animal welfare and human–animal interactions under these conditions. However, compared to this literature available in farm animals, and the plentiful studies conducted of feral horse populations, there is much less done when it comes to the management of horses kept in groups in the domestic environment. In particular, limited scientific information is available into the effect of group size and group composition on behaviour and methods of introducing new horses into established groups, even though problems related to social integration are repeatedly taken as arguments against keeping horses in groups.This review, therefore, aims to provide an overview of the current scientific knowledge regarding keeping horses in groups. Furthermore, it aims to give insight into whether or not some of the concerns related to keeping horses in groups are justified and to review scientifically based solutions that could be useful in practice to improve horse welfare and human safety.
... This occurred during Phase 2 while undergoing head lowering. Although it is possible that this horse may have been expressing submission to either humans or conspecifics (Miller, 1995), it could equally have been expecting feed (Houpt et al., 1978), attempting to solicit mutual grooming, or even snapping (Feist and McCullough, 1976). Similarly, it may have been smacking its lips as a displacement activity (Goodwin, 1999;Bachman et al., 2003) or as a manifestation of behavioral conflict (McGreevy, 2004). ...
Article
Horse trainers often report that lowering the height of a horse’s head so the poll is below the height of the withers can induce a calming effect during training. Four groups of horses were used in a 2-part study to investigate the behavioral and physiological effects of head lowering in horses. In Part 1, Group A had no experimental stimuli applied and horses in Group B were trained to lower their heads when presented with a specific stimulus by the handler. The stimulus for head lowering was the application of downward pressure on the headcollar via the lead rope until the horse lowered its head such that its lips were approximately at mid-cannon (third metacarpal) height, whereupon the pressure was released. The stimulus was applied again if the horse raised its head during the 300-second test period. In Part 2, Groups C and D were aroused until their heart rates exceeded 100 beats per minute (bpm). Group C had no further experimental stimuli applied whereas Group D lowered their heads as a response to the above stimulus for a period of 300 seconds. Repeated measures analysis showed that there was no difference between the heart rate of Groups A and B or Groups C and D but that the heart rate of Groups A and B were lower than Groups C and D during the 300-second post-arousal (P < 0.001). The horses in Groups A and B were more likely to contact the handler (P < 0.001), exhibit licking and chewing (P < 0.001), rest a hindleg (P < 0.001), and sniff the ground (P < 0.001) than those in Groups C and D. The number of stimuli required to maintain the head in a lowered position was greatest during the first 30 seconds (P = 0.012 and P < 0.001, Parts 1 and 2, respectively). The current study has shown that head lowering in horses does not influence cardiac responses, even after the horses had been aroused to have their heart rates above 100 bpm. Therefore, it is not a method that will aid in calming an aroused horse in training. Contrary to popular belief, there was no association with licking-and-chewing and head lowering, nor with these behaviors and response acquisition.
... On the other hand, very old horses often descend in the dominance hierarchy (Heitor et al., 2006;Keiper and Sambraus, 1986) and thus cause fewer displacements. Nonetheless, no consensus about the effect of age on rank in domesticated horses exists as some studies found a correlation (Clutton-Brock et al., 1976;Heitor et al., 2006;Montgomery, 1957) whereas others did not (Houpt et al., 1978;Pierard, 2012). ...
Article
Under natural conditions, horses spend 12–18 hours of a day with synchronous grazing, but for stabled horses, the amount of forage and thus duration of feed intake usually are restricted. In group-housed horses, therefore, feeding times are often situations with increased levels of agonistic behaviour. Our aim was to evaluate how forage provision, feeding duration and group composition influence agonistic behaviour. The study was conducted on 50 groups of 4–21 adult horses (n = 390) housed in group housing systems. Each group was observed for 30 minutes before and for the first 30 minutes after a hay feeding. Feeding systems were ‘floor’, ‘fodder rack’, ‘feed fence’, ‘net’, ‘feed stall with contact’, ‘feed stall no contact’ or a ‘combination’ of these. Hay was provided mostly 2–3 times per day but the duration of hay availability varied from 1.5–24 hours per day, whereas straw was mostly available ad libitum. Results showed that the proportion of horses showing agonistic behaviour was generally higher before than during feeding. Aggressive behaviour – bearing the risk of injuries by physical contact – was highest in ‘floor’ and lowest in ‘net’ ( = 13.0, p = 0.043). Aggressive behaviour decreased substantially during feeding with an increasing duration of hay availability ( = 7.1, p = 0.008). Threatening behaviour was highest in ‘floor’, ‘fodder rack’ and ‘feed fence’ and lowest in ‘feed stalls’ ( = 25.4, p < 0.001). Threatening behaviour increased with an increasing proportion of mares in the group ( = 5.0, p = 0.025). Displacements occurred most in ‘floor’ and least in ‘feed stalls’ ( = 37.37, p < 0.001). Additionally, displacements decreased substantially during feeding with an increasing duration of straw availability ( = 4.4, p = 0.035). Furthermore, horses fed at time-bound feeding times tended to show more locomotor activity before feeding than horses with no time-bound feeding times, whereas no difference was found during feeding (F1,321 = 3.62, p = 0.058). In conclusion, feeding places that are either individually separated by partitions or distant from each other lead to a reduced occurrence of agonistic behaviour, most likely because horses in such systems are able to maintain their perceived individual distances. Furthermore, it is highly recommended – from an ethological point of view – to provide not only straw but also hay over an unlimited period, regardless of the feeding system.
... As we were unable to achieve an objective measure of calmness in this trial, we cannot deduce that head lowering induces calmness, or that licking and chewing are signs of calmness. Perhaps the licking and chewing we observed here could be indicative of anticipation of food (Houpt et al., 1978), or being in a vulnerable position such as when grazing (Miller, 1995;Sighieri et al., 2003). ...
Conference Paper
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Globally, millions of horses are used for a range of purposes by humans with varying levels of skill in horse handling. Inappropriate handling techniques, especially those that cause flight responses or conflict behaviour, account for much of the wastage rates among horses as well as the majority of the deaths and injuries among handlers. In contrast, some techniques help to calm horses and thus facilitate training. Anecdotal evidence suggests that one such technique is lowering the height of a horse's head position. To determine the effect of head lowering, 20 horses were paired for age, sex and breed before one from each pair was allocated to Group 1 (treatment group: stimulus for head lowering applied during testing period) and the other placed into Group 2 (control group: no experimental stimulus applied during testing period). The stimulus for head lowering was downward pressure on the headcollar via the lead rope until the horse lowered its head such that its lips were approximately at mid-cannon height; as soon as this occurred the pressure was released. The testing period was 15 consecutive minutes divided into three 5-minute phases: Phase 1, in which neither group had experimental stimuli applied; Phase 2, in which Group 1 had the stimulus for head lowering applied and Group 2 had no stimuli applied; and Phase 3 that repeated the Phase 1 treatment. Behavioural responses of the head, neck and legs and the physiological responses of heart rate and heart rate variability were measured and analysed with one-way analysis of covariance. There were no significant differences between groups with any of the other responses measured, except for sniffing the ground (P=0.039), probably due to 76 the nature of the treatment. These results indicate that, under these conditions, head lowering does not result in increased calmness in horses.
... Paired feeding tests were conducted in each group to determine the rank status of each individual (51)(52)(53). Prior, all horses were introduced individually for 2 min to a bucket with concentrate feed which was used to cause competition during the paired encounters. When conducting the feeding test, each possible dyad of group members was tested in a random order; each individual was only tested in two consecutive encounters to allow the horses to recover from potential stress. ...
Article
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Horses can sleep while standing, however, recumbency is required for REM sleep and therefore essential. Previous research indicated a minimal duration of recumbency of 30 minutes per 24 hours to perform a minimal duration of REM sleep. For group-housed horses, suitable lying area represents a potentially limited resource. In Switzerland, minimal dimensions for the space allowance of the littered area are therefore legally required. To assess the effect of different space allowances of the littered area on lying behavior, 38 horses in eight groups were exposed to four treatments for 11 days each; T0: no litter provided, T0.5: 0.5x minimal dimensions, T1: minimal dimensions, and T1.5: 1.5x minimal dimensions. Non-littered areas were covered with hard rubber mats. Lying behavior was observed during the last 72 hours of each treatment. The total number of lying bouts per 24 hours was similar in treatments providing litter, whereas in treatment T0 recumbency occurred only rarely (F1,93 = 14.74, p = 0.0002) with the majority of horses lying down for less than 30 minutes per 24 hours (χ_1^2 = 11.82, p = 0.0006). Overall, the total duration of recumbency per 24 hours increased with increasing dimensions of the littered area, whereby the effect attenuated between treatment T1 and T1.5 in high-ranking horses but continued in low-ranking horses (F1,91 = 3.22, p = 0.076). Furthermore, low-ranking horses showed considerably more forcedly terminated lying bouts in treatments T0.5 and T1, but were similar to high-ranking horses in T1.5 (F1,76 = 8.43, p = 0.005). Nonetheless, a number of individuals showed durations of recumbency of less than 30 minutes per 24 hours even in treatment T1.5. The lying behavior was dependent on the availability of a soft and deformable surface for recumbency. A beneficial effect of enlarged dimensions of the littered area was shown by increased durations of recumbency and decreased proportion of forcedly terminated lying bouts in low-ranking horses. Taking this into account, it became evident that the minimal dimensions for the littered area as implemented in the Swiss animal welfare legislation do not ensure undisturbed lying behavior for all members of a given group.
... The acquisition of dominance is expected to depend on the recognition of several asymmetries among interacting animals, including asymmetries in resource holding potential (RHP) or fighting ability (Parker 1974;Parker and Rubenstein 1981;Packer and Pusey 1985;Arnott and Elwood 2009). Consistent with this view, it has been shown that in several species the dominance rank order is positively correlated to body weight and/or size that function as approximate measures of RHP (e.g., domestic horses, Equus caballus, Houpt et al. 1978; hens, Gallus gallus domesticus, Cloutier and Newberry 2000; red deer, Cervus elaphus, Veiberg et al. 2004; female reindeer, Rangifer tarandus, Holand et al. 2004;fallow deer, Dama dama, Jennings et al. 2006; free-ranging domestic cats, Felis silvestris catus, Bonanni et al. 2007). ...
Article
It is believed that domestic dogs rarely form packs with age-graded hierarchical structures similar to those found in wolves. Dog-wolf comparisons in captivity suggest that human control has reduced dog dependency on cooperation with conspecifics, resulting in a more despotic dominance order. However, free-ranging dogs are under stronger natural selection than purebred dogs. They are dependent on companions’ social support but usually exhibit lower reproductive skew than wolves, possibly because access to easily available human-derived food may have relaxed within-group competition. We investigated social dominance in 5 packs of mongrel dogs living in a free-ranging or semifree-ranging state. We aimed at replicating the findings of the few studies that detected a dominance hierarchy in dogs using a larger sample of packs. Additionally, we provided behavioral measures of social tolerance. We found that a linear hierarchy existed in all packs studied and that the rank order was positively related to age in all packs but one. In 2 packs in which testing was possible, age was a better predictor of dominance than body size. Potentially injurious aggression was very rare. Hierarchy steepness in dogs was similar to that found in wolves and in tolerant primates. Submissive reversals were more common in dogs than in wolves. These results suggest that age-graded hierarchies in dogs are more common than previously thought, that rank is not usually acquired through fighting because subordinates rely on the guidance of elders, and contradict the view that domestication has increased despotism in dogs.
... A slight negative relationship between age (in months) and hierarchy rank position in camels was shown (unstandardized regression coefficient β of −0.007, p < 0.05), which was annulled once regression coefficients were standardized. In a previous study with domestic horses, Houpt et al. [46] reached similar conclusions, as age appeared to influence neither agonistic behavior nor social structure within the herd. For companion dogs, Pal et al. [47] reported that within-group hierarchy was also not correlated to age. ...
Article
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Several idiosyncratic and genetically correlated traits are known to extensively influence leadership in both domestic and wild species. For minor livestock such as camels, however, this type of behavior remains loosely defined and approached only for sex-mixed herds. The interest in knowing those animal-dependent variables that make an individual more likely to emerge as a leader in a single-sex camel herd has its basis in the sex-separated breeding of Canarian dromedary camels for utilitarian purposes. By means of an ordinal logistic regression, it was found that younger, gelded animals may perform better when eliciting the joining of mates, assuming that they were castrated just before reaching sexual maturity and once they were initiated in the pertinent domestication protocol for their lifetime functionality. The higher the body weight, the significantly (p < 0.05) higher the score in the hierarchical rank when leading group movements, although this relationship appeared to be inverse for the other considered zoometric indexes. Camels with darker and substantially depigmented coats were also significantly (p < 0.05) found to be the main initiators. Routine intraherd management and leisure tourism will be thus improved in efficiency and security through the identification and selection of the best leader camels.
... In this context, dominant individuals are those who, by threat or aggression, get the best available resources [15] , while submissive ones surrender these resources to avoid conflicts. Furthermore, some individuals, regardless of their hierarchical position, perform the leadership role by being responsible for decisions and initiatives of collective motion [16] . ...
Article
Little is known about the dominance and leadership behaviors in the social structure of mules (Equus caballus × Equus asinus). Based on the frequency of threat and aggressive behaviors, we compared the social structure, dominance, and leadership of independent groups of mules and horses (n = 11 per group), and filmed the frequency of these behaviors over a period of four days. In both groups, aggressions were uncommon and, when based on threats, the social structure was linear and consistent with males ranking higher in dominance. When compared to horses, mules exhibited some agonistic social interactions without a recognized submissive individual and displayed more specific aggressive behaviors, whereas horses presented more specific threat behaviors. Comparing between groups, mares exhibited more leader behaviors than female mules, in contrast to male horses which showed fewer leader behaviors than male mules. Regarding behaviors within the mule group, males showed more leader and threat behaviors than females, while females showed more frequent aggression. While in horses, the females showed more leader behaviors than male horses and, although there were differences in specific agonistic behaviors, both sexes presented more often threat behaviors. In this preliminary study, we conclude that the social structure of mules, although similar to those of horses, showed to be less stable, since it involves more aggression and agonistic social interactions without a submissive. Moreover, although mules did not present a sex influence on leadership as horses did, they presented it on aggression: females showed more aggression than males.
... The degree of fearfulness was indicated by how much fear the horses displayed to unfamiliar reactions and how far they kept their distance from humans so that they were not caught [22]. The degree of dominance was indicated by the tendency of the horses to gain the upper hand over strangers or other horses and get priority of access to feed [23,24]. ...
Article
Oxytocin (OXT) and serotonin (5-HT) are essential neurotransmitters associated with the behavior of animals. Recently, we found that the plasma concentration of OXT is positively correlated with horse docility and friendliness toward humans. However, the relationships between the neurotransmitters and other temperaments such as fearfulness, dominance, and trainability are unknown. This study aimed to identify whether the plasma concentration of OXT or 5-HT is correlated with fearfulness, dominance, and trainability of horses. Blood samples of 34 horses were collected at the Horse Industry Complex Center of Jeonju Kijeon College. The concentration of OXT and 5-HT was measured in the plasma samples using enzyme-linked immunosorbent assays. The fearfulness, dominance, and trainability of horses were scored by three professors who were very familiar with the horses. One-way analysis of variance with the least significant difference post-hoc analysis was used to compare the scores for fearfulness and dominance among groups. The trainability of horses was compared using the student t-test. The 5-HT was negatively correlated with dominance, but it had no relation with fearfulness. The OXT appeared to be negatively correlated with fearfulness and dominance in horses. Furthermore, OXT was positively correlated with the trainability of horses. Additionally, 5-HT appeared to enhance trainability. In conclusion, the concentration of OXT or 5-HT in horse blood plasma can be used as a biomarker to monitor the fearfulness, dominance, or trainability of horses.
... Although the concept of dominance lacks universal explanatory power in describing social structure, it is a useful construct when considering the specific context of competition for a (Houpt, Law & Martinisi, 1978;Van Dierendonck, De Vries & Schilder, 1995;Hartmann, Christensen & McGreevy, 2017). ...
Article
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Individual animals experience different costs and benefits associated with group living, which may impact on their foraging efficiency in ways not yet well specified. This study investigated associations between social dominance, body condition and interruptions to foraging behaviour in a cross-sectional study of 116 domestic horses and ponies, kept in 20 discrete herds. Social dominance was measured for each individual alongside observations of winter foraging behaviour. During bouts of foraging, the duration, frequency and category (vigilance, movement, social displacements given and received, scratching and startle responses) of interruptions were recorded, with total interruption time taken as a proxy measure of foraging efficiency. Total foraging time was not influenced by body condition or social dominance. Body condition was associated with social dominance, but more strongly associated with foraging efficiency. Specifically, lower body condition was associated with greater vigilance. This demonstrates that factors other than social dominance can result in stable differences in winter body condition.
... According to the "social brain" hypothesis [144] the nature and complexity of social relationships reflects the cognitive demands for sociality, which in turn drove cerebral evolution in social mammals. Ungulates represents an ideal group to test theories about cognitive evolution since they display a huge variety of social behavior (ranging from almost solitary individuals, such as Tapirus [145], to large stable social group like in Equus [146]). Indeed, what is more surprising is that the total brain size is not significantly associated with group size in ungulates, but rather with social complexity in terms of inter-individual interactions on a regular basis and different types of relationships across group members. ...
Article
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Equine assisted interventions (EAIs) include all therapeutic interventions aimed at improving human wellbeing through the involvement of horses. Due to the prominent emotional involvement traditionally characterizing their relation with humans, horses developed sophisticated communicative skills, which fostered their ability to respond to human emotional states. In this review, we hypothesize that the proximate causation of successful interventions could be human–animal mutual coordination, through which the subjects bodily and, most importantly, emotionally come into contact. We propose that detecting emotions of other individuals and developing the capacity to fine-tune one’s own emotional states accordingly (emotional transfer mechanism), could represent the key engine triggering the positive effects of EAIs. We provide a comprehensive analysis of horses’ socio-emotional competences according to recent literature and we propose a multidisciplinary approach to investigate this inter-specific match. By considering human and horse as a unique coupling system during the interaction, it would be possible to objectively measure the degree of coordination through the analysis of physiological variables of both human and animal. Merging the state of art on human–horse relationship with the application of novel methodologies, could help to improve standardized protocols for animal assisted interventions, with particular regard to the emotional states of subjects involved.
... The six stallions in this study were the most aggressive individuals of their groups (frequencies of aggression ranging from 0.11 to 0.28/h) but compared to the other horses they were relatively non-aggressive. The finding agrees with other studies where it has been shown that stallions are neither especially dominant over females or more aggressive than other horses [42,43]. Also, in pure stallion groups, aggression levels have been found to be low [44]. ...
Article
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We explore how herd composition and management factors correlate with frequencies of social interactions in horse groups. Since the welfare of horses correlates with low aggression levels and social contact opportunities, information of this kind is important. The data are a collection of records of social interactions of 426 Icelandic horses in 20 groups of at least eight horses. The complexities and limitations of the data prohibit useful statistical modelling so the results are presented descriptively. Interesting and informative patterns emerge which can be of use both in management and in future studies. Of special interest are the low levels of agonistic behaviours in breeding groups where one stallion was present. The horses were less agonistic when in groups with young foals and where group membership was stable. Unfamiliar yearlings in peer groups were especially aggressive. Allogrooming was most frequent in groups with relatively more young horses and in unstable and small groups. Interestingly, the horses allogroomed more if they had few preferred allogrooming partners. The findings show that composition (age/sex) and stability of groups are of great importance with respect to aggression levels and opportunities for establishing bonds.
... This hypothesis agrees with other theories in that social contexts generate especially complex adaptive pressure towards organisms. Horses live in such complex social structures: They maintain a strict hierarchy within their herd (Houpt et al., 1978), form stable friendships (Feh &De Mazières, 1993 andSigurjónsdóttir et al., 2002) and they even infer information about their own position within the group from the observation of social interaction between others (Krüger & Heinze, 2007), to name just a few findings. Therefore, we can assume that horses have a noteworthy set of cognitive abilities. ...
Thesis
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The current study should, first, answer the outstanding question whether domestic horses can discriminate not only small but large discrete quantities as well, using a discrimination task between two different-sized sets of food items. Second, this study examined basic statistical reasoning in horses. Subjects had to choose between two one-item samples drawn from two visible distributions of stones and food items. In both tests horses showed a mean success rate significantly above chance level. A third experiment controlled for use of olfactory cues where mean success rate was at chance level, thus excluding this explanation. Therefore, this study proves large number discrimination in horses and is a first indicator that the ability to make inferences about single-event probabilities is not exclusive to higher primates.
Article
Changes in social hierarchy were evaluated in a herd of 3-year-old Hanoverian geldings. One group (n=5) was exposed to a training programme, the other (n=5) remained untrained. After 6 months, the groups were reversed. Hierarchical positions were evaluated by field observations and/or paired-feeding tests at the beginning, the middle, the end of the first and at the end of the second training period. Both methods yielded identical results. Almost all horses changed position in only one direction: either up or down. Neither increase in aggression nor mutual injuries were recorded during the whole experiment. No statistically verified differences in dominance ranking occurred between trained and untrained groups, but apparent differences were consistent. Thus, if horses are kept in the same group for a longer period of time, exercise induced changes in hierarchy are probably of minor importance and are unlikely to increase the incidence of injuries. This may have implications for the promotion of group-housing for sport horses.
Article
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I investigated the behavioural background of the way horses learn to follow humans in the “round pen technique” suggested by “horse whisperers” as a gentle method for initial horse training. Though the practicability of this technique has been adequately demonstrated in the past, the horses’ behaviour during such training has not yet been documented in detail. In a riding arena, horses, that did not follow the trainer immediately, were chased away so that they galloped around the trainer. Galloping horses showed specific behaviour such as turning the ear to the trainer, chewing, licking, and stretching head and throat downwards. In subsequent trials horses needed to be chased for less time and finally followed immediately, even when conditions were changed or the trainer was replaced by another person. This suggests that horses learn to follow in this particular situation and also show some generalisation. However, following did not occur on a pasture even after several successful trials in the riding arena.
Article
The relationships between 4-5 adult zebra stallions, living in a safari park, were investigated over a period of 5 years. Asymmetries in the distributions of a number of behaviours could be explained by adopting dominance as an intervening variable. Dominance in stallions was of a bipolar nature with on the one hand behaviours representing subordinance and defence, and on the other hand behaviours reinforcing and confirming dominance. Expression of formal dominance seems to play a minor role. The dyadic relationships of stallions differed as to the number of behaviours reflecting dominance relationships. Although often linear rank-orders could be constructed, these rank-orders were not necessarily identical. This means that the concept of dominance is of only limited value for describing relationships between zebra stallions.
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Tel: (286) 218 00 18 / 1326; Faks: (286) 218 05 45 Özet Çiftlik hayvanları sosyal türlerdir. Grup halinde yaşayan hayvanlar arasında sosyal hiyerarşinin tesisiyle, hayvanların sürekli olarak kavga etmesi, sosyal huzursuzluk önlenmektedir. Ancak sosyal hiyerarşinin hayvanlar arasında kaynakların kullanım sırasını da belirlediği unutulmamalıdır. Agonistik davranışlar hayvanlarda enerji kayıplarına, yaralanmalara ve sürüde genel bir huzursuzluğa yol açabilmektedir. Yetiştirme sistemi ve grup büyüklüğü sosyal davranışların sıklığını ve şeklini etkilemektedir. Hayvansal üretimde agonistik davranışların sıklığını en alt seviyede kalmasını sağlayacak, sürüde verim kayıplarını önleyecek yetiştirme uygulamaları yapılmalıdır. Bu çalışmada literatürden derlenen bilgilerle evcil hayvanlarda sosyal hiyerarşi ve agonistik davranışların irdelenmesi hedeflenmiştir. Abstract Most livestock are social-type species. The establishment of social hierarchy between animals living in groups reduces the social discomfort which occurs as a result of continuous fighting of animals. However it should be born in mind that social hierarchy determines the order in the use of resources between animals. Agonistic behaviours can cause waste of energy, injuries and a general discomfort in the herd. Husbandry system and group size affect the frequency and the type of social behaviour. Husbandry systems, which will reduce the frequency of agonistic behaviours and production losses, should be implemented. In this study, the evaluation of social hierarchy and agonistic behaviours in animals based on the information from the respective literature was aimed.
Article
Social interactions were recorded in two bands of free-ranging Przewalski horses living on large (greater than 30 ha) pastures in the Netherlands. The average number of aggressive interactions per hour was 8.86 at Lelystad and 10.36 at Noorderheide. The most common aggressive interactions were lower intensity, lower cost displacements (17.2% of all aggressive acts at Lelystad, 13.2% at Noorderheide), threats to bite (42.3% and 40.7%, respectively) and threats to kick (15.4% and 23.9%, respectively). Analysis of aggression revealed that a clear, linear dominance hierarchy was present in each band. For each band there was a positive and highly significant correlation between the age of a horse and its rank in the hierarchy. In each band, the stallion was not the highest ranked horse. Non-agonistic behaviors exceeded the number of agonistic interactions (1253 vs. 558 for Lelystad; 1257 vs. 995 at Noorderheide). There was a negative correlation between the rank of a horse in the dominance hierarchy and the number of non-agonistic behaviors displayed. The group displaying the highest number of non-agonistic interactions were foals (48.9% of total non-agonistic behaviors at Lelystad; 51.1% at Noorderheide). The non-agonistic/agonistic ratio was greater than 1 for yearlings and the band stallion, as was also the case for foals, but was less than 1 for males.
Article
The purpose of the following study was to determine if head partitions would facilitate feeding by subordinate horses in the presence of dominant pen-mates. Six pairs of mares, each with established dominant-subordinate relationships, were allowed to compete for feed in a 112-cm trough following 24 h of deprivation. Time spent feeding by each mare in each pair was recorded with a wire-mesh partition, a solid plywood partition or no partition dividing the trough.Differences in feeding times between dominant and subordinate mares were greatest in the absence of a partition and least (P<0.05) with the wire barrier in place. Differences in feeding times with the solid plywood barrier were not significantly different from either of the other treatment conditions.It was concluded that head partitions on a trough facilitate feeding by subordinate horses in the presence of dominant pen-mates and thus provide a more equitable distribution of food resources.
Article
A herd of 15 Belgian brood-mares and ten foals located at the Snyder Foundation Equine Research Center in Athens, Georgia was studied. Field data were collected using 30-min focal samples, such that 1 h of data was collected on each foal per week of its life. Social spacing was recorded at 2-min intervals. Social encounters during the focal sample were recorded on cassette tapes and later transcribed. The specific aspects of social structure studied were dominance-subordinance relationships, preferred associates, social spacing, aggression rates, the frequency of aggressions administered down the dominance hierarchy, and interactive play bouts. The rank order of the foals, both before and after weaning, was positively correlated with the rank order of their dams (Spearman's rho, P<0.02). There was also a significant relationship between a foal's rank and its total aggression or aggression rate per subordinate post-weaning. Higher ranking foals had higher rates of aggression (P<0.005). Over 80% of threats were directed down the dominance hierarchy. The play-rank order of the foals, scored by the number of times a foal left a play bout, was not significantly correlated with the rank order as scored by agonistic interactions (P>0.99).
Article
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Third-party interventions are defined as the interruption of dyadic interactions by third animals through direct physical contact, interposing or threats. Previous studies focused on the analysis of interventions against agonistic encounters. However, there have been no evaluations of interventions against affiliative behaviours, particularly in relation to the intervening animal's social relationships and its social and spatial position. Horses, Equus caballus, are an interesting model species, as interventions against affiliative interactions occur more frequently than against agonistic interactions. In this study, 64 feral horses displayed 67 interventions in affiliative interactions and eight interventions in agonistic interactions within the observation period. We analysed the interventions in affiliative encounters, and found that it was mainly higher-ranking females that intervened in the affiliative interactions of group mates in the stable horse harems. The intervening animals took an active part in affiliative and agonistic encounters within the group, but did not occupy particular social roles or spatial positions. They intervened in affiliative interactions in which group mates with which they had social bonds interacted with other members of the group. They targeted the nonbonded animal and approached the one with which they were socially bonded. We suggest some species use third-party interventions in affiliative interactions to prevent competition for preferred social interaction partners from escalating into more costly agonistic encounters.
Article
The tail of pigs has been suggested as a welfare indicator as it can provide insight into a pig’s behavioural and emotional states. Tail posture and motion have so far mainly been studied in the context of tail biting behaviour. The aim of this study was to investigate the relationship between pigs’ natural behaviour and their tail posture and tail motion. This was studied in a free-range farm in which tail biting is absent. In total 214 pigs of different age categories were observed individually (sows, gilts, boars, and 6-month old pigs) or by group (6-month and 1-year old pigs) for their tail posture, tail motion and behaviour, using live observations and videos obtained by drone. Results showed that a fully curled tail occurred most during locomotion (P < 0.001); and an actively hanging tail occurred more during foraging (P < 0.001), excavation (P = 0.006), feeding (P = 0.017), receipt of agonistic behaviour (P = 0.036), and non-agonistic social interactions (P = 0.046). A fully curled tail (P < 0.001) and a half curled tail (P < 0.005) occurred least in the group of sows. Tail motion was infrequent (6.7% of observations), and involved mainly loosely wagging, which occurred more during locomotion (P = 0.006) and non-agonistic social interactions (P = 0.006). A higher temperature-humidity index increased the probability of half curled tails (P < 0.001) and loose wagging (P < 0.001), while reducing the probability of active (P < 0.001) and passive hanging tails (P = 0.013). These results provide insight into tail posture and tail motion in pigs under semi-natural conditions, showing especially that hanging tails are not primarily associated with tail biting, and that the use of tail postures for welfare assessment should be in consideration with the context in which the animals are kept.
Article
The behavior of feral populations of the African wild ass (Equus africanus) were studied in the Northern Panamint Range of Death Valley National Monument for 20 months from 1970 to 1973 [Moehlman, P.D., 1974. Behavior and ecology of feral asses (Equus asinus). PhD dissertation, University of Wisconsin, Madison, 251 pp.; Moehlman, P.D., 1979. Behavior and ecology of feral asses (Equus asinus). Natl. Geogr. Soc. Res. Reports, 1970: 405–411]. Maintenance behavior is described and behavior sequences that were used in social interactions are quantified by sex and age class. Agonistic, sexual, and greeting behavior patterns are described and analyzed in conjunction with the responses they elicited. Mutual grooming mainly occurred between adult males, and between females and their offspring. Five types of vocalizations were distinguished: brays, grunts, growls, snorts, and whuffles. A second population was studied for 1 month on Ossabaw Island, GA (Moehlman, 1979). This population had more permanent social groups and had a higher rate of mutual grooming and foal social play.
Article
In polygynous species with high reproductive skew in males, mothers often show differential investment between sons and daughters. Although consistent sex differential investment has not been found by previous studies in horses, maternal investment beyond weaning has often been overlooked. We investigated sex differences in mother—offspring relationships in nutritionally independent sub-adult feral ponies, Equus ferus caballus. Stronger affiliative bonds between mothers and their sons than with their daughters were shown by their maintenance of closer proximity, higher rates of affiliative interactions and more frequent suckling bouts. These were associated with higher aggression levels directed towards sub-adult males by other band members, particularly stallions. We suggest that aggression may serve as the proximate mechanism driving male dispersal in feral horses and that the stronger mother—son bond signals an attempt to delay dispersal, highlighting conflict within the band concerning dispersal timing. Since we used social network theory to show that males become increasingly central within the band over time, we propose that delaying colts' dispersal allows for further development of social skills in a relatively safe environment, maximising their reproductive success. This study illustrates how social network theory can be used to quantify individuals' social experiences, contributing to a greater understanding of the evolution of group living.
Article
We investigated interventions by mother Jeju ponies on Jeju Island, Korea, to determine whether mothers assisted their offspring to attain higher status within the dominance hierarchy. Because dominance rank is important within each gender, we predicted that mothers would be more likely to intervene when their foals were play-fighting with foals of the same gender. A total of 173 play-fighting events were recorded from March to October 1998 and from April to October 1999. Of these, foals were more likely to play-fight with a foal of the same gender as with a foal of the opposite gender (120 versus 53 occurrences, respectively). A mother of one of the foals that were play-fighting intervened in 17 of these interactions. Contrary to the prediction, a mare was more likely to intervene when opposite genders interacted than when the same gender interacted. Analyzing interactions between the opposite genders further, mothers were equally likely to intervene when a daughter was play-fighting with a male foal as when a son was play-fighting with a female foal. Hence, mothers were not more protective of daughters than sons. Mothers that were in the younger age class ( years old) were as likely to intervene as those in the elder age class ( years old). However, all foals that were harassed were offspring of mothers in the younger, more subordinate age class. intervention directly maintains the dominance rank of the intervening mother, and may indirectly assist the intervening mother's foal to achieve a higher dominance rank. By discouraging their foals from play-fighting with the opposite genders, dominant mothers may be encouraging their foals to play-fight with the same gender and participate in establishing its own dominance rank.
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There is interest in the transportation of horses (Equus caballus) to slaughter and a need to assess the welfare implications of this practice. Forty-six loads of 7–35 horses transported for 0.33 to 3.10 h to a slaughter plant in Iceland were studied. Adults and foals were transported together and then placed in separate pens overnight in the lairage. This acted as a weaning procedure for the foals. Between one and eleven horses per load (59 adults and 129 foals) were observed during loading and at the slaughter plant, blood was sampled at slaughter and carcases were observed. No wounds were observed before transport, but 1.6% of horses had small, superficial bleeding wounds after transport. The respiration rate was greater after, compared to before, transport. Blood lactate concentration measured after lairage and slaughter was greater than normal in both adults and foals, 13% of adults and 20% of foals had a blood glucose concentration lower than normal, and 58% of adults and 25% of foals had a plasma total protein concentration greater than normal. Forty-four percent of adults and 17% of foals were bruised. There were no pre-existing conditions affecting the fitness of the horses for transportation. The effects of transport on the physiological responses and the severity of bruising were relatively minor. However, the results suggested that the handling, transport and lairage of the horses resulted in injury and signs of exertion or stress that were not compatible with optimal management practices. The mild dehydration in adults might have been associated with restricted access to drinking water during lairage of lactating mares. Controlled studies are required to identify the specific practices used in Iceland that result in injury and dehydration.
Article
Horses are motion animals and only feel safe when living in groups. Therefore housing conditions are increasingly implemented, where social contacts are possible all day long. They are expected to allow for more welfare, but at the same time demand a higher level of management. The present review aims at a deeper understanding and know-how on dominance relations in horses kept in groups. Ethological and experimental studies on feral and domestic horses are known for more than 30 years. Despite differences in methodological approaches field-observations or experimental test situations all agree that grouped horses establish an almost linear dominance ranking of social hierarchy. This is interpreted as an adaptive tool to avoid continous aggressive conflicts between group members. Endogenous factors that may influence dominance rank position have been a matter of discussion: Neither sex nor reproductive state seem to matter decisively, while age - juvenile or adult - seems to matter. Criteria such as height, weight, temperament and genetic provenience are debated. The role of other factors such as health, training condition or previous experience need further exploration and scientific evidence.
Article
Early studies on determinants of social interactions among animals typically focused on the influence of factors such as age, sex, physical attributes, group size or environment. Variation within categories of these factors was often regarded as uninteresting 'noise'. However, during the past two decades individual variation in behaviour within populations has received increasing attention from researchers. Consistent individual differences in behaviour expressed by personality traits have been studied both from mechanistic and functional perspectives in several animal taxa and have been shown to affect fitness. Personality is also shaped by the social and non-social environment. In group-living species, an individual's behaviour and the choices it makes are influenced by the behaviour and choices of group members. Social learning is one such form of influence, which can modulate the patterns of social interactions and relationships within a group. Personality traits and social learning have been reported to affect social and nonsocial behaviour (e.g. foraging, exploratory behaviour, dominance, aggression, mate choice) in several animal species. However, research on the influence of animal personality and social learning on the several dimensions of social behaviour is still warranted and we believe it would shed new light on the development of social relationships. Therefore, we discuss previous research and suggest future directions for the study of the influence of personality and social learning on social interactions among nonhuman animals.
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The time budget, frequency of physiological necessities and factors related to dominance rank were studied in Cold Blooded Breed (CBB) and Warm Blooded Breed (WBB) male horses. The subjects were investigated during the 1st h in a paddock after confinement in the morning and again in the afternoon. Proportion of feeding was the largest among time budget activities and significantly different (p<0.05) between observation periods. Proportions of locomotion, resting and playing were statistically different (p<0.05; p<0.01 and p<0.001) between both breeds and both observation periods. No differences were found for living activities such feeding, drinking and elimination (urination and defecation) between the CBB and WBB horses. Dominance hierarchy was linear and positively correlated (p<0.01) with weight but not serum testosterone levels and age. The results showed that feeding activity was very important at the 1 st h in the paddock. Additionally, the weight of the colts had an effect on dominance rank.
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Previous research documented that furosemide negatively impacted calcium balance for 3 days but did not determine when calcium balance returned to baseline. This study hypothesized that furosemide's impact on calcium would return to control values before 7 days post‐administration. Ten mature geldings were assigned to either control (CON, n = 5) or treatment (FUR, n = 5) for the first of two 8‐day total collections in crossover design. Treatment horses received one administration of furosemide (1 mg/kg, IV). A 10% sample of pooled faeces and urine from each day was kept. Calcium concentrations in hay, faeces and urine were determined by an atomic absorption spectrophotometer. Data were analysed using mixed‐model‐repeated measures ANOVA to determine influence of day and treatment. For urine output, FUR urinated twice as much during the 24 hr after administration than CON (p < .001). Horses in FUR excreted more urinary calcium 24‐hr post‐administration as compared to CON (9.3 ± 1.0 and 4.2 ± 1.0 g, respectively; p < .001). Calcium balance in FUR was more negative on day 1 than day 3 (p < .05). Faecal calcium concentrations remained the same from day 1 to day 7 in CON (6.3 ± 1.3 and 5.5 ± 1.3 g/kg, respectively; p > .10) but were lower in FUR on day 7 as compared to day 1 (4.8 ± 1.3 and 7.3 ± 1.3 g/kg, respectively; p < .001), indicating a potential mechanism to restore calcium balance. These findings corroborate previous studies on furosemide and calcium balance and provide evidence for a possible mechanism to recover net calcium losses after furosemide administration. Since calcium balance returns to baseline in 3 days and previous results have examined frequent, long‐term use, furosemide may not negatively impact bone mineral content even if used over long periods.
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Although herd size, structure, stability, and social rank among Misaki feral horses have been reported, no studies have been conducted on the affiliative relationships and interactions among members in a Misaki horse herd. The validity of three hypotheses regarding the function of social grooming, the affiliative relationship strengthening hypothesis, the worsened relationship restoring hypothesis, and the grooming parasite removal hypothesis, were tested in a Misaki feral horse (Equus caballus) herd in Cape Toi, Japan. All the nine horses in the "6m" herd were investigated in terms of kinship, grooming, aggression, proximity, social rank, and social network. Mutual grooming occurred only in pairs and was almost perfectly symmetrical. For each member, there was a significant negative correlation between total grooming received from other individuals and self-grooming. Controlling for kinship, there were significant positive partial correlations between mutual grooming and proximity and between aggression and proximity. No correlation was observed between aggression and mutual grooming. The results suggest that mutual grooming symmetry may contribute that both participants simultaneously benefit from parasite removal and strengthen affiliative relationships between seasonally changing herd members; however, mutual grooming did not foster restoring the worsened relationship following aggression promoted by physical proximity. The findings of this study may elucidate the mechanisms by which interactions between herd members are maintained or strengthened.
Article
Grazing muzzles are a popular and effective management tool used to help prevent weight gain in obese-prone equids. Concerns have been raised over their possible negative impact on horse well-being as muzzles may interfere with normal grazing and social behaviors. The objective of this study was to assess the effects of grazing muzzles used for different lengths of time on behavior, voluntary exercise, and physiological stress of grazing horses housed in a herd. Six mature miniature horses (initial BW of 114.9 ± 11.4 kg; BCS of 6.0 ± 0.8) were studied using a 3 × 3 Latin Square repeated measure design with horses receiving one of three treatments daily for a period of 3 weeks. Treatments were unmuzzled (M0), muzzled for 10 h/d (M10, 0830-1830 h), or muzzled for nearly 24 h/d (M24). Horses were housed as a herd on a 0.6 ha grass pasture. Body weight (BW) was assessed weekly. Reaction to muzzle application was scored daily. Behavior was monitored with video twice weekly for two hours a day. An aggressiveness rank was assigned to each horse each period. Physiological stress was assessed weekly using changes in heart rate (HR), indices of heart rate variability, and salivary cortisol concentrations (SC). Voluntary exercise was measured for 24 h twice during each period. Data were analyzed as repeated measures with treatment and wk as main effects. Horses muzzled for 24 h/d lost BW while horses muzzled 0 or 10 h/d gained BW (P = 0.01). Horses muzzled for 24 h/d spent more time grazing (P = 0.04) and less time resting (P = 0.03) than M10 horses. Unmuzzled horses spent more time walking than M24 horses (P < 0.01), more time cantering than M10 (P = 0.02), and more time trotting than M10 and M24 (P = 0.04 and 0.01 respectively). Both muzzled treatments spent less time autogrooming with their mouths than unmuzzled horses (P < 0.01). Horses muzzled for 24 h/d had lower HR than M0 horses (P = 0.01) and higher beat-to-beat intervals than M0 and M10 horses (P = 0.01 and 0.03 respectively) while grazing. There were no effects of treatment on muzzle acceptability score, salivary cortisol, voluntary exercise, or change in aggressiveness rank. In conclusion, muzzling for 24 h/d prevented weight gain and did not cause apparent physiological stress. The lower HR and higher beat-to-beat interval in horses muzzled 24 h may be a potential health benefit and needs further exploration.
Article
Once the COVID-19 pandemic started and the UK went into lockdown on 17th March 2020, many horse owners had to change their horse keeping practices. Exactly how varied depending on their exact circumstances. Horses kept at home, or on full and part livery, would have experienced little change other than a reduction in ridden exercise as some owners chose to stop riding to reduce the risk of personal injury. Owners of horses kept at DIY yards faced greater difficulties as, in many cases, their visits reduced in frequency, horse care rotas were not being adopted, and horse management shared with other owners; this, coupled with uncertainty about future income raising anxiety levels in some individuals, may have had knock on effects for horse behaviour. The pandemic also contributed to some unexpected effects. Increased public footfall in the countryside meant more horses being uncontrollably fed by members of the public, and horse sales continued, even increased, with rehoming from some welfare organisations following the same trend.
Article
The social hierarchy of a herd of 12 draft mares was assessed using agonism in the field, paired-feeding tests and a group-feeding test. Results from the paired-feeding test correlated significantly, but imperfectly, with those from the field. Differential motivation among subjects for the feed and disruption of ambiguous relationships among mares reduced the reliability of the paired-feeding test as a measure of social dominance. Results from the group-feeding test did not correlate significantly with the field hierarchy and only a few mares ever ate from the bucket. Height, weight and age each correlated significantly with rank; a mare's tendency to remain alone did not. Total aggressive scores during the paired-feeding test correlated with rank. However, a high-ranking mare was no more aggressive to each of her subordinates than was a low-ranking mare. Rather, all mares aggressed more against individuals close in rank to themselves and with preferred field associates. In the field, mares associated most with other mares of similar rank.
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1. The normal pattern of social behaviour in growing Large White and Berkshire pigs is described. The pigs were observed from 8 to 16 weeks of age in pens of 6 to 10 pigs. Large Whites were more aggressive than Berkshires. 2. Social rank was found to be positively correlated with initial weight. 3. Initial weight and social rank both influenced growth; the relative effect of rank compared with that of initial weight was greater in the second month than in the first. 4. The contribution of social rank to the total variance in growth over the 2-month period was estimated at about 13%. 5. It is suggested that the use of individual housing in pig progeny test schemes may not be desirable because of the absence of social environmental effects.
Article
The object of this study has been to describe a type of social organization existing within a herd of dairy cattle, and to explore the effects of this organization on the behaviour of the individuals. Some of the ramifications of the organizational patterns are explored in an effort to trace the development of the organization. A rather detailed description of the physical plant and management routines at the station where these studies were conducted is presented in the first section of the dissertation, so that the reader who is unfamiliar with dairy herd practices may better understand the ensuing discussion. Aggressive behaviour patterns of the individual are also described in detail so as to afford the reader a clearer understanding of the role of the individual in the group. Such behaviour apparently follows a definite sequence, each phase of which is discussed in detail. The various links in the chain of aggression are termed: the approach, the threat, the physical contact, and the ensuing victory or defeat. The approach may be active or passive; while passive approach merely describes the chance meeting of two cows engaged in random wandering, active approach implies purposeful behaviour on the part of one or both of the animals. Direct physical contact between two animals involves either butting or actual fighting. Butting is defined as when one animal uses its forehead to direct a blow at another without any retaliatory action on the part of the struck animal. On the other hand, fights occur when the struck cow strikes back. Commonly, a fight consists of a series of encounters; the actual encounters do not last for more than about a minute at a time and invariably end with one animal taking flight. The interval between encounters may vary from a few seconds to five minutes, with “displacement grazing” being the major activity between encounters. Actually, most contesting actions observed did not progress further than the threat stage, although these contests are considered just as decisive as if they had progressed through the fight phase. Each group in the herd was observed for at least one hour a week during the course of this study. During the observational period, careful notes were kept of each animal involved in a contest, and the outcome of the, contest was recorded. Close to 5,000 individual contests were recorded and were plotted on a large master chart. The pattern of wins and losses clearly indicated that the herd was organized in a straight-line peck-order very much like that previously described by workers in the field of domestic fowl. The dominance order was compared to the ages, weight and production records of the animals. A highly significant relationship obtained between rank and age and also between rank and weight, but the relationship between rank and milk production was inconclusive. The correlation between rank and the failure to complete a full lactation period was of a low order of significance and therefore not considered further. In an effort to separate age and weight from seniority, two completely strange cows were introduced into a group of fourteen animals from the experimental herd. After the new group had stabilized, the dominance order was again plotted and it was found that the two introduced cows were very much “out of line” with respect to age and weight. Later, when the two strange cows were introduced to two high ranking animals from the experimental herd, the group of four set up a rather elaborate circular type of dominance order. This particular order did not show any relationship to age or weight, although it was markedly affected by the previously established relationships within the pairs of animals. Hence, it is concluded from these results that although age and weight are closely allied to the social scale pattern in the herd, they are probably not causally related. The data are suggestive that in normal herd management, seniority, as depicted by age or weight, is of primary importance in the determination of rank position. The socal position of each animal is probably determined at three to six months of age, when she first encounters large, group living conditions.
Article
Between October 1965 and October 1968 nearly 4000 hr were spent observing the semi-wild ponies in the New Forest. Observations were made mainly in daylight in two study areas totalling over 5 square miles and containing about 300 mares, their offspring and up to twelve stallions. Qualitative and some quantitative data were obtained on aspects of maintenance behaviour including grazing, resting, elimination and grooming, but the social organization of the ponies received more attention. Ponies were associated into small groups of which about 60 per cent were family groups consisting of one adult mare and a number of her offspring; about 28 per cent consisted of two mares and their offspring and only 12 per cent of more (up to six) mares. Associations between adult unrelated mares were very stable but immature ponies changed groups. Any stallion generally became associated with one mare group. The organization of the ponies has been compared with that of other wild equids. Dominance-subordinance relationships between mares in a group and of different groups which regularly came into contact were also stable; hierarchies were chiefly linear but some were complicated by triangular relationships. The rank of a mare was largely dependent on her age and size. Stallions were dominant over most mares in competition for food, but mares in oestrus or with young foals did threaten stallions. Mutual grooming occurred most commonly between members of a group or between related ponies in different groups. Each group occupied a small, stable home range but home ranges of different groups freely overlapped. Diurnal and seasonal patterns of movements were recorded within the ranges. Auditory, visual and olfactory means of communication between ponies have been described. A detailed study of the changing mother-young relationship was made by means of check sheets on which the behaviour of mares and their foals was recorded every ½ min for 1 hr, at intervals throughout the foals' first year. Data were analysed to compare the behaviour of colts and fillies and that of foals of primiparous mares and of multiparous mares, and to assess differences in behaviour with time of day, but chiefly to demonstrate changes in the behaviour of mare and foals with the foals' age. Play was observed between immature ponies and between immature and adult ponies. Colts played more frequently than did fillies. Various aspects of sexual behaviour, particularly the active behaviour of mares in oestrus in seeking out stallions, and changes in stallions' behaviour during the breeding season, are described.
Article
Carbon copy of typescript. Thesis (M.S.)--University of Nevada, Reno, 1971. Includes bibliographical references.
Article
Recent studies of primates have questioned the importance of dominance hierarchies in groups living under natural conditions. In a herd of Highland ponies and one of Highland cattle grazing under free-range conditions on the Isle of Rhum (Inner Hebrides) well defined hierarchies were present. The provision of food produced a marked increase in the frequency of agonistic interactions but had no effect on the rank systems of the two herds. While rank was clearly important in affecting the distribution of agonistic interactions, it was poorly related to behaviour in non-agonistic situations.
Article
The social behavior of feral horses was studied in the western United States. Stable harem groups with a dominant stallion and bachelor hermaphrodite hermaphrodite groups occupied overlapping home ranges. Groups spacing, but not territoriality, was expressed. Harem group, stability resulted from strong dominance by dominant stallions, and fidelity of group members. Eliminations of group members were usually marked by urine of the dominant stallion. Hermaphrodite-hermaphrodite aggression involved spacing between harems and dominance in bachelor groups. Marking with feces was important in hermaphrodite-hermaphrodite interactions. Foaling occurred in May and early June, following the post-partum estrous. All breeding was done by harem stallions. Young were commonly nursed through yearling age. These horses showed social organizations similar to other feral horses and plains zebras.
Article
Dominance has been assumed to be a quality of overwhelming social importance but satisfactory definitions and measures have not been devised. As an indication of predictability of outcome of interaction between animals, it can be explained in terms of ordinary learning processes previous to and during a specific relationship. Agonistic interactions are usually determined and often initiated by the subordinate's behavior, and subordinate behavior is correlated with physiological changes, so that a subordination hierarchy is probably a more useful concept than a dominance hierarchy. Hierarchies develop in stressful conditions, especially in captivity where animals with overresponsive adrenal cortices are at a selective disadvantage. In wild groups hierarchies are tenuous or absent and stress-responsive members are probably advantageous to a group. Group defense and leadership roles are not correlated with rank, but policing is characteristic of high-ranking animals in species where it occurs. There is no evidence that formation of a hierarchy reduces aggression—hierarchies are actually associated with high rates of aggression in primate groups. There is no conclusive evidence that high ranking males have greater overall reproductive success, and an alternative hypothesis that adult males are sexually active for a relatively short stage of their lives fits existing data equally well.
Elementary Statistics
  • Croxton
Croxton, F.E., 1953. Elementary Statistics. Dover, New York, p. 376.
Practical Animal Husbandry Some aspects of the sociality of the domestic horse
  • W C Miller
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Miller, W.C. and Robertson, E.D.S., 1952. Practical Animal Husbandry. Oliver and Boyd, Edinburgh, 607 pp. Montgomery, G.G., 1957. Some aspects of the sociality of the domestic horse. Trans. Kans., Acad. Sci., 60: 419-424.
Dog Behavior The Genetic Basis
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Dominance hierarchies in domestic horses
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Stebbins, M.C., 1973. Dominance hierarchies in domestic horses. Master-s Thesis, Idaho State University.
Practical Animal Husbandry
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Miller, W.C. and Robertson, E.D.S., 1952. Practical Animal Husbandry. Oliver and Boyd, Edinburgh, 607 pp.
Rangordnungsversuche mit Pferde
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Home range territoriality and movement patterns of wild horses in the Wassuk Range of western Nevada
  • Pelligrini
Pelligrini, S.W., 1971. Home range territoriality and movement patterns of wild horses in the Wassuk Range of western Nevada. Masters Thesis, University of Nevada.
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