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Wolter, R., & Krueger, K. (2015). The analysis of social bonds in feral horses. In Proceedings of the 3. International Equine Science Meeting.
Abstract: In many social mammals, individuals preferentially affiliate with a small subset of available partners instead of distributing their social behaviors equally among all group members. The resulting social bonds have been investigated in several mammalian taxa, especially in primate societies, but also in other taxa such as birds, dolphins, rodents and ungulates. In feral horses, a great number of studies on social bonds can be found, but with a huge variety between methods for the analysis. There seems to be a lack of a clear and common definition of social bonds in horses and of comparable analyses. For example, there are irregularities between the studies regarding the research designs, the selection of recording methods and the interpretation of the measurements. Mutual grooming is used most often for the analysis of social relationships in many species. As mutual grooming is rare in horses, especially measurements of spatial proximity are commonly used for the analysis of social bonds in addition to other behavioral patterns. However, the combination of mutual grooming and nearest neighborhood analyses for the analysis of social bond is debatable, as in contrast to mutual grooming, which must occur deliberately by both grooming partners, the spatial distribution can be influenced by one partner alone, which may even force the other horse to keep a certain distance or to stay in close proximity.
In this study, we investigated the comparability of mutual grooming and nearest neighborhood data for social bond analyses in feral horses. Therefore, we observed five groups of semi-wild living Przewalski’s horses and six groups of feral horses. We analysed the horses’ social ranks by applying an Average Dominance Index, we recorded the distances between the animals and observed the number of mutual grooming events as well as friendly approaches. Our results show that there was only a weak correlation between the frequency of staying in nearest neighborhood and mutual grooming in all observed horse groups. In contrast to this, the correlation between the number of friendly approaches and mutual grooming events was higher in most groups. Hierarchies did not affect social bonds, as mutual grooming was similarly induced by higher and lower ranking animals and the social rank did not affect the choice of the grooming partner. Similarly, likelihoods of staying in the neighborhood of particular animals were not affected by the animals’ social rank. The grooming frequencies differed between the different horse groups and between the individual horses living in the particular groups. They seem to be effected by individual predisposition. Altogether we suggest that the ratio of mutual grooming seems to be a better indicator for social bonds in feral horses than the frequency of staying in the nearest neighborhood. Mutual grooming occurs deliberately and is bidirectional, whereas nearest neighborhoods could be enforced and unidirectional. For the calculation of social bonds in horses, we consider it to be more reliable to combine the frequency of mutual grooming with the frequency of friendly approaches. |
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Vervaecke, H., Vries, H. D., & Elsacker, L. V. (1999). An Experimental Evaluation Of The Consistency Of Competitive Ability And Agonistic Dominance In Different Social Contexts In Captive Bonobos. Behaviour, 136(4), 423–442.
Abstract: Bonobos have been described as a relatively egalitarian and female dominant species. The exact nature and quality of their dominance relationships and the existence of female dominance are current topics of dispute. We investigated the consistency across social contexts, the stability in time, and the degree of expression of the competitive feeding ability and agonistic dominance in a captive group of bonobos. First, we examined whether the competitive feeding ranks and agonistic ranks differed in different dyadic contexts, triadic contexts and the whole group context. For some pairs of animals the dominance relationships with respect to competitive feeding altered with different group compositions. The agonistic dominance relationships changed accordingly. The competitive feeding ranks and agonistic ranks in the experiments correlated strongly with each other. The alpha position was occupied by a female, but not all females outranked all males. We suggest that females can profit from each others presence to gain inter-sexual dominance. Second, although the agonistic rank order in the whole group remained the same over at least five years, some dyadic competitive feeding ranks changed over time, resulting in a stronger female intersexual dominance. Third, the degree of expression of the behaviors used to quantify dyadic competitive and agonistic dominance was not high, in line with the popular 'egalitarian' epithet. Notwithstanding its low consistency across contexts, the dominance hierarchy in the whole group has a strong predictive value for other social relationships such as grooming. Given this strong effect of rank on other behaviours and given the strong dependency of rank on social context, the choice of the right party members may be a crucial factor in the fission-fusion processes of free-ranging bonobos.
Keywords: BONOBO PAN PANISCUS; RANK ORDERS; FEEDING SCORES; AGONISTIC RANKS; PEERING
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VanDierendonck, M. C., de Vries, H., & Schilder, M. B. H. (1995). An Analysis of Dominance, Its Behavioural Parameters and Possible Determinants in a Herd of Icelandic orses in Captivity. Netherl. J. Zool., 45(3-4), 362–385.
Abstract: Th e applicability of the concept of dominance was investigated in a captive herd of  Icelandic
horses and  ponies of diff erent breeds. Eight out of  behaviours possibly related to dominance occurred frequently enough to be investigated in detail. For these eight agonistic behaviours the coverage, the unidirectionality in the exchange, and the degree of transitivity (Landau`s linearity index) were calculated. Four off ensive behaviours, together with avoidance, were suitable for further analysis with regard to dominance. Th e patterns of asymmetries with which these behaviours were exchanged were suffi ciently similar as to justify the application of the dominance concept and to construct a (nearly) linear dominance hierarchy. Th e rank order of the castrated stallions was completely linear, the hierarchy of the mares was almost completely linear. Th e results suggest that off ensive and defensive aggressive behaviours should be treated separately and that the concept of dominance is applicable. However, ritualized formal dominance signals between adult horses appear to be (almost) absent. Th e rank positions of the individuals were correlated with age and residency in the herd but not with height. Middle ranking horses tended to be more frequently in the close vicinity of another horse than high ranking or low ranking horses. Over and above this correlation at the individual level, it was found that pairs of horses close in rank to each other were more often also spatially close to each other. Being in oestrus did not infl uence the dominance relationships between mares. For castrated stallions the rank positions were correlated with the age at which they were castrated. Th is suggests that in male horses experience prior to neutering infl uences the behaviour afterwards. Keywords: Dominance; rank order; horses; Icelandic horses.
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VanDierendonck, M. C., de Vries, H., Schilder, M.B.H. (1995). An Analysis of Dominance, Its Behavioural Parameters and Possible Determinants in a Herd of Icelandic horses in captivity. Netherl. J. Zool., 45(3-4), 362–385.
Abstract: Feral horses are social animals, which have to rely on survival strategies centered on the formation of cohesive social bonds within their bands. Many problems in the husbandry of social animals such as horses, are due to the fact that the limits of their adaptive abilities are exceeded. Evidence suggests that the fundamental social characteristics of domestic horses have remained relatively unchanged. The social structure, social strategies and social interactions were investigated (3 non-consecutive years, 24 hr per day for several weeks) in long term established groups of domestic horses (mares and geldings of all ages) and a few small introduced groups, kept in (semi)natural environments. The general aim was to investigate the social needs of domestic horses. The social life of domestic horses was characterised by long lasting bonds with preferred partners which were established and maintained by allogrooming, play, proximity and dominance behaviours. Bonding partners were mainly found within the same sex-age group, but adult geldings also bonded with sub-adult mares and geldings. Adult mares were clustered in a group, while the other animals formed a second group. Among the adult mares, subgroups according to reproductive state were formed. Individuals regulated their social network by interfering with interactions between other members of the herd, which in itself is complex. An intervention is a behavioural action of one animal that actively interferes with an ongoing interaction between a dyad with the apparent aim of altering that interaction. This was verified by post-hoc analyses of disturbed and undisturbed interactions. Interventions in allogrooming or play were performed significantly more often when at least one member of the initial dyad was a preferred partner of, or familiar to (within the small introduced bands) the intervener. The stronger the preferred association in allogrooming between the intervener and member(s) of the initial dyad, the higher the probability the intervener would displace one initial member and continue allogrooming with the other. Just five behaviours were extracted which reliably reflected the dominance relations among horses. Aggression with the hind quarters was used both offensively and defensively and therefore not suitable as a reliable parameter. Individual dominance relationships were related to social experience. The implications of these findings for horse husbandry were assessed. It is argued that the execution of affiliative behaviours may be rewarding in itself, and therefore always will be a highly motivated behaviour. It is shown that social positive physical interactions (allogrooming, play) with other horses is an ethological need and therefore indispensable in modern husbandry systems. Ethological needs are so important for the animal that husbandry systems that lack the possibilities to execute such behaviours will cause chronic stress. It is concluded that all horses need physical social contact, and that horses, which lack appropriate social learning experiences during ontogeny, may be hampered in their social functioning later in life. Solutions for problems, including dominance problems, in individual social housing and group housing are presented.
Keywords: Dominance; rank order; horses; Icelandic horses.
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Taillon, J., & Côté, S. (2008). Are faecal hormone levels linked to winter progression, diet quality and social rank in young ungulates ? An experiment with white-tailed deer ( Odocoileus virginianus ) fawns. Behav. Ecol. Sociobiol., 62(10), 675–677.
Abstract: Abstract Hormones play a central role in the physiology and behaviour of animals. The recent development of noninvasive techniques has increased information on physical and social states of individuals through hormone measurements. The relationships among hormones, life history traits and behaviours are, however, still poorly known. For the first time, we evaluated natural winter glucocorticoid and testosterone levels in young ungulates in relation to winter progression, diet quality and social rank. Overwinter, levels of glucocorticoid and testosterone decreased, possibly due to the decline of fawns" body mass. The relationships between hormone levels and diet quality were surprising: Fawns fed the control diet presented higher glucocorticoid and lower testosterone levels then fawns fed the poor diet, suggesting that control fawns faced a higher nutritional stress than those on the poor diet. Similarly to other studies on social mammals, we found no relationship between faecal glucocorticoid levels and social rank, suggesting that social stress was similar for dominant and subordinate fawns during winter. Testosterone levels were not correlated to social rank as found previously in groups of individuals forming stable social hierarchies and maintaining stable dominance relationships. The simultaneous suppression of glucocorticoid and testosterone levels suggests for the first time that young ungulates present a hormonal strategy to prevent fast depletion of limited proteins and fat resources during winter.
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Stashak, T. S., & Wissdorf, H. (2007). Adams' Lahmheit bei Pferden. Hannover: Schaper M. & H.
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Smith, J. E., Kolowski, J. M., Graham, K. E., Dawes, S. E., & Holekamp, K. E. (2008). Social and ecological determinants of fission-fusion dynamics in the spotted hyaena. Anim. Behav., 76(3), 619–636.
Abstract: Theory predicts that individuals living in fission-fusion societies, in which group members frequently change subgroups, should modify grouping patterns in response to varying social and environmental conditions. Spotted hyaenas, Crocuta crocuta, are long-lived carnivores that reside in permanent social groups called clans. Clans are complex, fission-fusion societies in which individual members travel, rest and forage in subgroups that frequently change composition. We studied two clans in Kenya to provide the first detailed description of fission-fusion dynamics in this species. Because social and ecological circumstances can influence the cohesiveness of animal societies, we evaluated the extent to which specific circumstances promote the formation of subgroups of various sizes. We found that cooperative defence of shared resources during interclan competition and protection from lions were cohesive forces that promoted formation of large subgroups. We also tested hypotheses suggesting factors limiting subgroup size. Mothers with small cubs avoided conspecifics, thereby reducing infanticide risk. Victims of aggression either reconciled fights or separated from former opponents to reduce the immediate costs of escalated aggression in the absence of food. As predicted by the ecological constraints hypothesis, hyaenas adjusted their grouping patterns over both short and long time scales in response to feeding competition. Crocuta were most gregarious during periods of abundant prey, joined clanmates at ephemeral kills in numbers that correlated with the energetic value of the prey and gained the most energy when foraging alone because cooperative hunting attracted numerous competitors. Overall, our findings indicate that resource limitation constrains grouping in this species.
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Schneider, G., & Krueger, K. (2012). Third-party interventions keep social partners from exchanging affiliative interactions with others. Anim. Behav., 83(2), 377–387.
Abstract: 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.
Keywords: Equus caballus; horse; rank; social bond; social network; third-party intervention
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Obergfell, J. (2012). Einf lus s v on St ruktur e l ement en auf da s Li eg ev e rha l t en v on Pf e rden in Gruppenha l tung unt e r Be rücks i cht igung de s Ag g r e s s i ons v e rha l t ens. Ph.D. thesis, , Karlsruhe.
Abstract: Durch die vorliegende Studie wurde der Einfluss von Strukturelementen auf das Liege- und Aggressionsverhalten von Pferden in Gruppenhaltung untersucht. Die Strukturelemente sollten Rückzugsmöglichkeiten bieten, sowie in ihrem Bereich zur Aufhebung der Individualdistanz führen und dadurch die Fläche relativ vergrößern. Für die Versuche stellte das Haupt- und Landesgestüt Marbach drei unabhängige Pferdegruppen mit verschiedener Herdengröße zur Verfügung, die jeweils in Einraum- Innenlaufställen gehalten wurden. Die Datenerfassung fand zwischen 23 und sieben Uhr statt. Insgesamt wurden 366 Stunden Videomaterial ausgewertet. Beim Ruheverhalten wurden mit Hilfe des event-sampling- Verfahrens die Parameter Gesamtliegedauer, Dauer in Seitenlage, Dauer der Einzelphasen in
Seitenlage und Abliegehäufigkeit pro Nacht erfasst. Es wurden Versuchsphasen ohne Strukturelemente und mit hängenden Planen als Strukturierung durchgeführt. Im ersten Stall kamen außerdem über einander gestapelte Strohballen zum Einsatz. Diese Art der Strukturierung stellte sich jedoch als nicht praktikabel heraus und führte im Vergleich zu den Planen zu einer signifikanten Verschlechterung der Gesamtliegedauer. In Stall 1 konnte man eine tendenzielle Verbesserung der Parameter Gesamtliegedauer und Gesamtdauer in Seitenlage durch das Anbringen von Planen sehen. In Stall 3 dagegen verschlechterte sich das Ruheverhalten in den Versuchsphasen mit Planen gegenüber den Versuchsphasen ohne Struktur. Die Werte der Gesamtdauer in Seitenlage nahmen signifikant ab. In Stall 2 zeigten sich keine Unterschiede in den verschiedenen Versuchsphasen. Möglicherweise ist die Wirkung der Strukturelemente auf das Liegeverhalten abhängig von der Flächengröße. Stall 1 hatte bezogen auf die Leitlinien des BMELV die größte und Stall 3 die kleinste Fläche. Bei den anderen Parametern des Liegeverhaltens gab es keine signifikanten Unterschiede in den verschiedenen Versuchsphasen. Mit Hilfe des time-sampling-Verfahrens wurde die Anzahl gleichzeitig liegender Pferde und gleichzeitig liegender Pferde in Seitenlage bestimmt. Auch hier zeigten sich keine Unterschiede in den verschiedenen Versuchsphasen. Bei der Gegenüberstellung der Werte der Gesamtliegedauer und der Gesamtdauer in Seitenlage mit dem Alter der Pferde (Stall 1 und Stall 3) und mit dem Integrationszeitpunkt (Stall 1) konnte kein Zusammenhang festgestellt werden. Beim Aggressionsverhalten wurden mit Hilfe des event-sampling-Verfahrens in den Ställen 2 und 3 verschiedene Arten von Aggressionen erfasst, die dann in die drei Intensitätsgrade Low-Level-, Mid-Level- und High-Level- Aggressionen unterteilt wurden. Neben der Anzahl wurde die Dauer der verschiedenen Aggressionen bewertet. Insgesamt konnte eine positive Wirkung der Planen auf das Aggressionsverhalten beobachtet werden. Die Gesamtanzahl an Aggressionen nahm in beiden Ställen tendenziell in den Versuchsphasen mit Planen ab. In Stall 3 konnte, wenn man die Aggressionen stundenweise betrachtet, ein signifikanter Unterschied festgestellt werden. Auch der Hinterhandschlag und die Aggressionen, welche das Ruheverhalten stören, verringerten sich tendenziell nach dem Anbringen von Strukturelementen. In beiden Ställen nahm die relative Häufigkeit von Mid-Level-Aggressionen nach dem Anbringen von Planen zu. Dagegen konnte bei den High-Level-Aggressionen und in Stall 3 bei den Low-Level- Aggressionen eine relative Abnahme beobachtet werden. Sowohl die Anzahl als auch die Dauer der Mid-Level-Aggressionen verringerten sich in Stall 3 stundenweise betrachtet signifikant in den Versuchsphasen mit Planen. In Stall 2 war bei den High-Level- Aggressionen sowohl bei der Dauer als auch bei der Anzahl eine signifikante Abnahme zu sehen. Wenn man das Aggressionsverhalten in Bezug zu der Fläche in den zwei Ställen betrachtet, schien diese vor allem einen Einfluss auf die High-Level-Aggressionen zu nehmen. Mit Hilfe des Rangindex der Pferde im Stall 3 wurde eine Rangordnung aufgestellt. Zwischen dem Platz der Pferde in der Rangordnung und den Parametern des Ruheverhaltens (Gesamtliegedauer, Gesamtdauer in Seitenlage) sowie dem Alter der Pferde konnte kein Zusammenhang festgestellt werden. Zwischen dem Rangindex und der Gesamtanzahl an Aggressionen bestand dagegen ein hoch signifikanter Zusammenhang. Im Rahmen dieser Studie ist das Anbringen von Strukturelementen in Bezug auf das Aggressionsverhalten in Einraum-Innenlaufställen von Pferden zu empfehlen. Die Wirkung auf das Liegeverhalten der Pferde sollte in weiteren Studien untersucht werden. [In this study the influence of structural elements on lying and aggression behavior in horses kept in groups was exanimated. Structural elements should offer the possibility of retreat. Furthermore, within the respective area, the individual distance should be limited, thus increasing the overall space relatively. For the studies the “Haupt- und Landesgestüt Marbach” provided three non-related groups of different sized horses, each kept in separate “Einraum-Innenlaufställen”. Data collection took place between 11 pm and 7 am. Altogether, 366 hours of video material were analyzed. Using the event-sampling-method, the following parameters within the horses´ resting behavior were determined: The total lying period, the total lying period in lateral position, the periods of the single lying in lateral position and the frequency of lying down. Test phases were carried out without structural elements and with hanging canvases as structural elements. In the first stable there were also three bales of straw piled up on top of each other. This kind of structuring emerged as impractical and in comparison to the canvas, led to a significant deterioration to the total period of lying. After the canvases were fixed in the first stable, a slight improvement with the parameters of total lying period and total lying period in the lateral position could be seen. In contrast, the resting behavior in stable 3 worsened in the test phases with the canvases in comparison to the test phases without structural elements. The values for the total lying period in the lateral position decreased significantly. In stable 2, there were no differences in the different test phases. Possibly the effect of the structural elements is dependent of the space. Stable 1 had the largest space and stable 3 the least space referred to the guideline of the BMELV. The other parameters of the lying behavior showed no significant differences in the different test phases. The number of horses lying at the same time, and the number of horses lying at the same time in the lateral position were detected with the aid of the time-sampling-method. There were also no differences between the different test phases. If the values of the total lying period and the total lying period in lateral position were compared to the age of the horses (stable 1 and stable 3) and to the point of integration (stable 1), there was no correlation. Different kinds of aggression were detected by the means of the event-sampling-method in stable 2 and 3 and were subdivided into the three levels of intensity: Low-level-, mid-level and high-level-aggressions. Both the number and the duration of the different aggressions were evaluated. All in all a positive influence of the canvas on the aggression behavior could be observed. In both stables, the total number of aggressions decreased in the test phases with canvases. In stable 3 a significant difference could be detected, if the aggressions were observed per hour. Also hind limb kicks and aggressions disturbing the resting behavior, decreased by trend, after fixing the canvases in the stable. In both stables the relative frequency of mid-level-aggressions increased after the canvases were mounted. In contrast there was a relative decrease at the high-level-aggressions and in stable 3 at the low-levelaggressions. The number and the duration of the mid-level-aggressions in stable 3 decreased, when considered by the hour in the test phases with canvases. In stable 2 a significant decrease in duration and number of high-level-aggressions was observed. When examining aggression behavior in reference to space in the two stables, high-level-aggressions seemed to be mostly influenced. In stable 3 a rank order was established with the aid of the rank index of the horses. There was no correlation between the horses´ rank and the parameters of the resting behavior (the total lying period, the total lying period in lateral position) and between horses´ rank and age. In contrast, there was a high significant correlation between the rank index and the total number of aggressions. In context to this study, structural elements in “Einraum-Innenlaufställen” (BMELV 2009) seem to have a positive influence on the aggression behavior and thus seem to be recommendable. The influence on the lying behavior should be investigated in further studies.] |
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Neumann, C., Duboscq, J., Dubuc, C., Ginting, A., Irwan, A. M., Agil, M., et al. (2011). Assessing dominance hierarchies: validation and advantages of progressive evaluation with Elo-rating. Animal Behaviour, 82(4), 911–921.
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