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| Author | Bouskila, A.; de Vries, H.; Hermans, Z.M.; van Dierendonck, M. | ||||
| Title | Leadership roles in movements of free-roaming Konik horses (Equus caballus) in a Dutch reserve | Type | Conference Article | ||
| Year | 2012 | Publication | Proceedings of the 2. International Equine Science Meeting | Abbreviated Journal | Proc. 2. Int. Equine. Sci. Mtg |
| Volume | in press | Issue | Pages | ||
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| Abstract | We observed the activity and movements of Konik horses (Equus caballus) in order to determine the initiators of movements and the individuals taking the lead in movements of the main groups. We conducted our observations between March-June 2010 along the shores of the Rhine river, in the Blauwe Kamer reserve, in the Netherlands. The horses were introduced to the reserve alongside with cattle to prevent the growth of the forest and maintain the grass habitat. We videotaped all observations on two digital video cameras, one providing the general view of the group and the other scanning and focusing on the individuals, to aid with identification. Horses were recognized based on individual profiles that were created for each one, consisting of photos of both sides and notes of the main characters, such as orientation and coloration of the mane, prominent scars and markings, etc. Twenty three horses (not counting foals) were organized in two harem groups with 11 individuals (two of which were dominant stallions) in the large group and six individuals (one of which was a stallion) in the second group. These two main groups were always within sight of each other, and two bachelor males moved usually in their vicinity. An additional group of three young bachelor males roamed elsewhere in the reserve. We divided the movements of the horses to local movements while grazing and to long-distance movements, in which the horses moved to a different grazing location, to a pond of water, resting area or groups of trees that were used by the horses for scratching themselves. During the local movements, any two of the three oldest females in the large harem group were enough to cause the whole group to follow them and gradually change position within the pasture. The smaller harem always followed the large harem’s movements. The long-distance movements of the large harem were sometimes initiated by one of the harem stallions that herded their group and at other times – by the oldest females. Soon after the movement was clearly initiated, the dominant stallions positioned themselves in the back of the group or in the center and had no influence on the direction of move that was only determined by the leading females. In the long-distance movements too, the small harem followed the large harem group, and the two bachelor males usually followed behind them. Social interactions included aggressive interactions between the two dominant males within the large harem or between dominant stallions and the two bachelor males accompanying the two harems. In addition, dominant males courting or attempting to mate with mares sometimes caused a turmoil that eventually initiated movement of the harems. KW - | ||||
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| Corporate Author | Bouskila, A. | Thesis | |||
| Publisher | Xenophon Publishing | Place of Publication | Wald | Editor  |
Krueger, K.; |
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| ISSN | 978-3-9808134-26 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Equine Behaviour @ team @ | Serial | 5592 | ||
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| Author | VanDierendonck, M.C.; de Vries, H.; Schilder, M.B.H. | ||||
| Title | An Analysis of Dominance, Its Behavioural Parameters and Possible Determinants in a Herd of Icelandic orses in Captivity | Type | Journal Article | ||
| Year | 1995 | Publication | Netherlands Journal of Zoology | Abbreviated Journal | Netherl. J. Zool. |
| Volume | 45 | Issue | 3-4 | Pages | 362-385 |
| Keywords | Dominance; rank order; horses; Icelandic horses. | ||||
| 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. |
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| Language | English | Summary Language | Original Title | ||
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| Call Number | refbase @ user @ | Serial | 440 | ||
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| Author | Gammell, M.P.; de Vries, H.; Jennings, D.J.; Carlin, C.M.; Hayden, T.J. | ||||
| Title | David's score: a more appropriate dominance ranking method than Clutton-Brock et al.'s index | Type | Journal Article | ||
| Year | 2003 | Publication | Animal Behaviour. | Abbreviated Journal | Anim. Behav. |
| Volume | 66 | Issue | 3 | Pages | 601-605 |
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| Call Number | refbase @ user @ | Serial | 453 | ||
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| Author | de Vries, H.; Stevens, J.M.G.; Vervaecke, H. | ||||
| Title | Measuring and testing the steepness of dominance hierarchies | Type | Journal Article | ||
| Year | 2006 | Publication | Animal Behaviour. | Abbreviated Journal | Anim. Behav. |
| Volume | 71 | Issue | 3 | Pages | 585-592 |
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| Abstract | In the analysis of social dominance in groups of animals, linearity has been used by many researchers as the main structural characteristic of a dominance hierarchy. In this paper we propose, alongside linearity, a quantitative measure for another property of a dominance hierarchy, namely its steepness. Steepness of a hierarchy is defined here as the absolute slope of the straight line fitted to the normalized David's scores (calculated on the basis of a dyadic dominance index corrected for chance) plotted against the subjects' ranks. This correction for chance is an improvement of an earlier proposal by de Vries (appendix 2 in de Vries, Animal Behaviour, 1998, 55, 827-843). In addition, we present a randomization procedure for determining the statistical significance of a hierarchy's steepness, which can be used to test the observed steepness against the steepness expected under the null hypothesis of random win chances for all pairs of individuals. Whereas linearity depends on the number of established binary dominance relationships and the degree of transitivity in these relationships, steepness measures the degree to which individuals differ from each other in winning dominance encounters. Linearity and steepness are complementary measures to characterize a dominance hierarchy. | ||||
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| Call Number | refbase @ user @ | Serial | 454 | ||
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| Author | de VRIES, H.A.N. | ||||
| Title | Finding a dominance order most consistent with a linear hierarchy: a new procedure and review | Type | Journal Article | ||
| Year | 1998 | Publication | Animal Behaviour. | Abbreviated Journal | Anim. Behav. |
| Volume | 55 | Issue | 4 | Pages | 827-843 |
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| Abstract | A procedure for ordering a set of individuals into a linear or near-linear dominance hierarchy is presented. Two criteria are used in a prioritized way in reorganizing the dominance matrix to find an order that is most consistent with a linear hierarchy: first, minimization of the numbers of inconsistencies and, second, minimization of the total strength of the inconsistencies. The linear ordering procedure, which involves an iterative algorithm based on a generalized swapping rule, is feasible for matrices of up to 80 individuals. The procedure can be applied to any dominance matrix, since it does not make any assumptions about the form of the probabilities of winning and losing. The only assumption is the existence of a linear or near-linear hierarchy which can be verified by means of a linearity test. A review of existing ranking methods is presented and these are compared with the proposed method. | ||||
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| Call Number | refbase @ user @ | Serial | 457 | ||
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| Author | Albers, P.C.H.; de Vries, H. | ||||
| Title | Elo-rating as a tool in the sequential estimation of dominance strengths | Type | Journal Article | ||
| Year | 2001 | Publication | Animal Behaviour. | Abbreviated Journal | Anim. Behav. |
| Volume | 61 | Issue | 2 | Pages | 489-495 |
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| Call Number | refbase @ user @ | Serial | 858 | ||
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| Author | De Vries, H.; Appleby, M.C. | ||||
| Title | Finding an appropriate order for a hierarchy: a comparison of the I&SI and the BBS methods | Type | Journal Article | ||
| Year | 2000 | Publication | Animal Behaviour. | Abbreviated Journal | Anim. Behav. |
| Volume | 59 | Issue | 1 | Pages | 239-245 |
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| Call Number | refbase @ user @ | Serial | 869 | ||
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| Author | Vervaecke, H.; Stevens, J.; Vandemoortele, H.; Sigurjönsdöttir, H.; De Vries, H. | ||||
| Title | Aggression and dominance in matched groups of subadult Icelandic horses (Equus caballus) | Type | Journal Article | ||
| Year | 2007 | Publication | Journal of Ethology | Abbreviated Journal | J. Ethol. |
| Volume | 25 | Issue | 3 | Pages | 239-248 |
| Keywords | Equus – Dominance – Aggression – Hierarchy – Steepness | ||||
| Abstract | Abstract We studied sex differences in the nature of aggression and dominance behaviour in two newly formed groups of 1-year-old Icelandic horses. One herd contained nine geldings, the other nine mares. The groups were matched with regard to dominance-determining traits such as age, weaning age, composition of native herd, social experience, genetic origin, body condition and maternal dominance status. High-ranking individuals of both sexes were more aggressive, high-ranking males were older, and high-ranking females had a better body condition. Frequencies of aggressions were similar in both groups. The mares reacted significantly more by showing submission upon an aggression rather than by not responding or by escalating the aggression. For the geldings, this difference was not observed due to a lower tendency to submit. A linear dominance hierarchy was found in both groups. David`s scores provided additional information regarding cardinal rank distances and were used to calculate steepness of hierarchies. The female hierarchy was somewhat steeper compared to the male hierarchy, suggesting somewhat lower despotism among males. This was mainly a consequence of the lower unidirectionality in male submission. Male contests occurred predominantly between dyads at top and mid positions, suggesting a low degree of acceptance of the hierarchy. | ||||
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| Call Number | Equine Behaviour @ team @ | Serial | 2192 | ||
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| Author | Stevens, J.; Vervaecke, H.; De Vries, H.; Van Elsacker, L. | ||||
| Title | Social structures in Pan paniscus: testing the female bonding hypothesis | Type | Journal Article | ||
| Year | 2006 | Publication | Primates | Abbreviated Journal | Primates |
| Volume | 47 | Issue | 3 | Pages | 210-217 |
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| Abstract | Abstract Based on previous research in captivity, bonobos, Pan paniscus, have been called a female-bonded species. However, genetic and behavioural data indicate that wild females migrate. Bonding between these unrelated females would then be in contradiction with socio-ecological models. It has been argued that female bonding has been overemphasized in captive bonobos. We examine patterns of proximity, grooming and support behaviour in six well established captive groups of bonobos. We find that female bonding was not a typical characteristic of all captive bonobo groups. In only two groups there was a trend for females to prefer proximity with other females over association with males. We found no evidence that following or grooming between females was more frequent than between males and unrelated females or between males. Only in coalitions, females supported each other more than male-female or male-male dyads. We also investigated five mother-son pairs. Grooming was more frequent among mothers and sons than in any other dyad, but sons did not groom their mothers more than males groomed unrelated females. Mothers groomed their sons, or provided more support to them than females groomed or supported unrelated males. Thus, while bonds between females were clearly present, intersexual relations between males and either unrelated females or their mothers are of more, or equal importance. | ||||
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| Call Number | Equine Behaviour @ team @ | Serial | 2193 | ||
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| Author | Stevens, J.; Vervaecke, H.; de Vries, H.; Van Elsacker, L. | ||||
| Title | The influence of the steepness of dominance hierarchies on reciprocity and interchange in captive groups of bonobos (Pan paniscus) | Type | Journal Article | ||
| Year | 2005 | Publication | Behaviour | Abbreviated Journal | Behaviour |
| Volume | 142 | Issue | 7 | Pages | 941-960 |
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| Abstract | Biological market models explain variability in reciprocity and interchange between groups. In groups with a shallow dominance gradient, grooming will be mostly exchanged for itself (i.e. exchange will occur). In groups with steep dominance hierarchies, interchange is expected: individuals will groom higher ranking individuals to get access to limited resources or commodities such as support in conflicts, and grooming will be traded for these commodities. We examine patterns of reciprocity in grooming and support, and of interchange of grooming for support or for tolerance in six captive groups of bonobos. We test whether differences between groups in patterns of reciprocity and interchange can be attributed to differences in a measure of steepness of dominance hierarchies, which is based on dyadic agonistic interactions. We found that grooming was reciprocal in some, but not all groups. Support was highly reciprocal, but this was a side effect of dominance in most groups. Interchange between grooming and support was observed in some groups. Corroborating earlier findings, this was a side effect of individuals preferring high ranking individuals as grooming and support partners, possibly because these high-ranking individuals provide more efficient support in conflicts. There was no evidence for interchange of grooming for tolerance. Variability in grooming reciprocity was explained by differences in steepness of dominance hierarchies, as predicted by the biological market models. In groups with a shallow dominance hierarchy, grooming was more reciprocal. This was not true for reciprocity in support. There was some evidence that individuals groomed dominants more frequently in groups with a steep dominance hierarchy. The variation in interchange relations between grooming and support did not depend on the steepness of dominance hierarchies. We suggest that grooming in itself is a valuable commodity in bonobos, especially under captive conditions, which can be exchanged reciprocally. Bonobos may interchange grooming for another value equivalent, with food sharing as a very likely candidate. This interchange effects seem more dependent on potential to monopolise food than on steepness of dominance hierarchies per se. | ||||
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| Call Number | Equine Behaviour @ team @ | Serial | 2194 | ||
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