Published online by Cambridge University Press: 27 February 2018
Horses are a gregarious species with strong social bonds between individuals and when under free-ranging conditions, form family bands or herds (Tyler, 1979; Wells and Goldschmidt-Rothschild, 1979). Each herd contains small bands of roughly 3 adult horses (1 stallion, 2-3 mares) plus their most recent offspring (Linklater et al., 1999). There are also bachelor groups composed of males that are either too young for their own harems, or can no longer defend the harems they once had (Waring, 1983). As horses live in groups they have evolved a complex behaviour repertoire in order to communicate. Mutual grooming and play are two such behaviours that have been widely studied in both domestic and feral horses, however the results from studies on their influencing factors have been contradictory. Mutual grooming has the obvious function of coat care and parasite removal; moreover, it has also been implicated in forming and maintaining bonds between horses in a herd (Waring, 1983).