|Farm in Iceland--Cornell university|
The researchers observed a herd of 26 Icelandic horses (6 geldings, 16 mares, 2 young stallions, and 2 young mares) and 5 ponies of different breeds at a farm in the Netherlands over a period of 6 months in 1984. The horses were pastured year round with access to water, shelter, and food. The non-Icelandic horses, young horses, and one mare with a probable hormonal disorder were excluded from the study. The horses had been together for several years.
Dominance behaviors were defined as offensive aggressive behaviors (attack, bite, threat to bite, approach with ears flattened,) versus avoidance. Defensive aggressive behaviors were kick, threat to kick, and buck. Based on these observed behaviors the scientists could build a strictly linear relationship among the Icelandic geldings and mares. The top five places in rank were taken by the older Icelandic mares with the sixth place held by a gelding with the rest of the rankings interspersed among mares and geldings.
Between sexes, certain lower ranking members could be dominant to higher ranking individuals.
- Age correlated with rank in the mixed sex herd ranking and among mares but not among the geldings.
- Height did not correlate with rank when males and females were considered separately. However height did correlate with the entire herd ranking with smaller horses ranking higher in this herd.
- Length of residency in the herd correlated higher with rank.
- Rank position surprisingly did not correlate well with amount of aggression displayed.
- Submission correlated with rank.
- Age at castration linked with sexual experience correlated with rank. In other words, the amount of sexual experience and the opportunity to develop and practice male displays rather than age of castration per se influenced ranking among geldings.
- Mares with foals temporarily can gain in herd ranking.
- Ranking of adult mares correlated positively with their adult offspring.
- If a mare exhibited more aggressive behavior, her offspring was likely to be observed exhibiting more frequent aggressive behavior (which could be due to heredity and/or learned behavior).
This study did not observe and correlation between rank and allogrooming, kinship, and social bonds. However pairs of horses closer in rank tended to spend more time close to each other.