Journal of Ethology

, Volume 25, Issue 3, pp 239–248 | Cite as

Aggression and dominance in matched groups of subadult Icelandic horses (Equus caballus)

  • Hilde Vervaecke
  • Jeroen M. G. Stevens
  • Harold Vandemoortele
  • Hrefna Sigurjónsdóttir
  • Han De Vries


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.


Equus Dominance Aggression Hierarchy Steepness 



We thank Johann B. Magnusson of the Bessastadir ranch in Iceland and all the ranches that allowed the use of their horses in this study. We kindly thank Machteld Van Dierendonck (University of Utrecht) for her assistance. Iceland University of Education supported the research. Harold Van de Moortele set up the study and performed the observations during his training as psychological assistant at the Department of Psychology of the Lessius Institute in Antwerp, Belgium. Hilde Vervaecke was funded by the Fund for Scientific Research Flanders (FWO). Jeroen Stevens was funded by the IWT. The CRC thanks the Flemish Government for financial support. We kindly thank the reviewers for their suggestions.


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Copyright information

© Japan Ethological Society and Springer 2006

Authors and Affiliations

  • Hilde Vervaecke
    • 1
    • 6
  • Jeroen M. G. Stevens
    • 2
    • 3
  • Harold Vandemoortele
    • 4
  • Hrefna Sigurjónsdóttir
    • 4
  • Han De Vries
    • 5
  1. 1.KAHO Sint-LievenUniversity of Leuven, Ethology GroupSint-NiklaasBelgium
  2. 2.Royal Zoological Society of AntwerpCentre for Research and ConservationAntwerpBelgium
  3. 3.Department of BiologyUniversity of AntwerpWilrijkBelgium
  4. 4.Iceland University of EducationReykjavíkIceland
  5. 5.Department of Behavioural BiologyUtrechtThe Netherlands
  6. 6.SamréeBelgium

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