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Author Heitor, F.; do Mar Oom, M.; Vicente, L.
Title (up) Social relationships in a herd of Sorraia horses: Part II. Factors affecting affiliative relationships and sexual behaviours Type Journal Article
Year 2006 Publication Behavioural Processes Abbreviated Journal Behav. Process.
Volume 73 Issue 3 Pages 231-239
Keywords Horse; Equus; Affiliative relationship; Rank; Kinship; Aggressiveness
Abstract The influence of age, dominance rank, kinship and aggressiveness over affiliative relationships and sexual behaviours were analysed in a herd of Sorraia horses, Equus caballus, kept under extensive management. Subjects were 10 adult mares 5-18 years old that had known each other since birth, and a stallion introduced into the group for breeding for the first time. Kinship coefficient and dominance rank were the most important factors affecting affiliative relationships. Bonds were reciprocal and stronger among mares with higher kinship. Mares spent more time in proximity to close-ranking and lower-ranking females. Mares with stronger affiliative relationships or higher relatedness were not less aggressive towards each other. Affiliative relationships between the stallion and the mares were not reciprocal: lower-ranking mares formed stronger bonds with the stallion but he preferred the less genetically related mares for proximity. However, the stallion was involved in sexual behaviours more frequently with the mares that were more genetically related to him. These results suggest that kinship beyond close relatives may affect affiliative relationships both among familiar and among unfamiliar horses. However, the influence of kinship does not imply that horses possess a kin recognition system and alternative explanations are discussed.
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Call Number refbase @ user @ Serial 462
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Author Wolter, R.; Krueger, K.
Title (up) The analysis of social bonds in feral horses Type Conference Article
Year 2015 Publication Proceedings of the 3. International Equine Science Meeting Abbreviated Journal Proc. 3. Int. Equine. Sci. Mtg
Volume Issue Pages
Keywords social bonds, grooming, nearest neighborhood, rank
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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Corporate Author Wolter, R. Thesis
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN ISBN 978-3-95625-000-2 Medium
Area Expedition Conference
Notes Approved no
Call Number Equine Behaviour @ team @ Serial 5882
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Author Hemelrijk,C. K.; Wantia,J.; Gygax,L.
Title (up) The construction of dominance order: comparing performance of five methods using an individual-based model Type Journal Article
Year 2005 Publication Behaviour Abbreviated Journal Behaviour
Volume 142 Issue 8 Pages 1043-1064
Keywords dominance order, ranking method, agent-based model, statistical method, aggression
Abstract In studies of animal behaviour investigators correlate dominance with all kinds of behavioural

variables, such as reproductive success and foraging success. Many methods are used to

produce a dominance hierarchy from a matrix reflecting the frequency of winning dominance

interactions. These different methods produce different hierarchies. However, it is difficult to

decide which ranking method is best. In this paper, we offer a new procedure for this decision:

we use an individual-based model, called DomWorld, as a test-environment. We choose this

model, because it provides access to both the internal dominance values of artificial agents

(which reflects their fighting power) and the matrix of winning and losing among them and,

in addition, because its behavioural rules are biologically inspired and its group-level patterns

resemble those of real primates. We compare statistically the dominance hierarchy based on

the internal dominance values of the artificial agents with the dominance hierarchy produced

by ranking individuals by (a) their total frequency of winning, (b) their average dominance

index, (c) a refined dominance index, the David`s score, (d) the number of subordinates each

individual has and (e) a ranking method based on maximizing the linear order of the hierarchy.

Because dominance hierarchies may differ depending on group size, type of society, and the

interval of study, we compare these ranking methods for these conditions.We study complete

samples as well as samples randomly chosen to resemble the limitations of observing real

animals. It appears that two methods of medium complexity (the average dominance index

and David`s score) lead to hierarchical orders that come closest to the hierarchy based on

internal dominance values of the agents. We advocate usage of the average dominance index,

because of its computational simplicity.
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Notes Approved no
Call Number refbase @ user @ Serial 445
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Author Schneider, G.; Krueger, K.
Title (up) Third-party interventions keep social partners from exchanging affiliative interactions with others Type Journal Article
Year 2012 Publication Animal Behaviour Abbreviated Journal Anim. Behav.
Volume 83 Issue 2 Pages 377-387
Keywords Equus caballus; horse; rank; social bond; social network; third-party intervention
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.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-3472 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Equine Behaviour @ team @ Serial 5492
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