Hrefna Sigurjonsdottir
University of Iceland
Iceland
Title: Which variables affect most agonistic and affiliative behavior in pastured adult horses?
Biography
Biography: Hrefna Sigurjonsdottir
Abstract
Results from studies of social interactions (aggressive, submissive, allogrooming, play) in 17 groups of pastured Icelandic horses (329 in total) are used in multivariate analyses (PCA and GLM). The composition of the groups and conditions varied stability, group size, proportions of geldings/mares/sub-adults and presence of newborn foals, presence of stallions (6 groups) and more. Both individual and group characteristics determined the type of social interactions performed by each horse. Geldings were both more aggressive and submissive than either mares or stallions. Adult play was almost restricted to geldings. The higher the ratio of sub-adult to adults, the rates of aggression, play and allogrooming also gets higher. Group stability was highly influential on the frequency of the different social interactions. Both aggression and submission decreased with increasing stability, while allogrooming was more frequent in unstable groups and play in nearly stable groups. Such effect of stability was not observed in the breeding groups with a stallion. One major finding was that the frequency of social interactions, especially agonistic interactions, was much lower in the breeding groups than in other groups. These results are important in terms of understanding the determinism of social interactions. Their relevance for horse group management and horses’ welfare is also clear.
