Formation of family groups
The Przewalski's horse form small family groups that consist of an adult stallion, one to three mares, and their offspring. In addition, young males and those expelled from a family group by another stallion often form groups of bachelor stallions.
Within and among these families, Przewalski's horses display a complex set of behaviours:
Stand resting or grazing close to another individual indicates a significant preference, often linked to age or relatedness (a foal will remain close to its mother). The function of this proximity is to maintain connections between individuals and so to enforce the cohesion of the group.
This is contact between the noses of two individuals (or nose-body contact). Horses can detect a lot of olfactive information through sniffing, but the transmission and treatment of this information is still not well understood.
Grooming is observed between individuals who are close to each other, often between a mare and her foal. These interactions reinforce the cohesion of the group and ameliorate social stress.
Play is first seen in horses when they are just a few weeks old. Play sessions can be observed among foals and the young stallions in a bachelor group. Play can include kicks, bites and chases.
Dominance interactions are also observed early in a horse's life and are the expression of relative places in the hierarchy between individuals. Dominance hierarchy affects horses in many ways, particularly for access to water, food, and choice of partners. Dominance hierarchies exist both within and between groups. Dominance interactions typically observed include charges, bite threats, bites and kicks.
This behaviour is expressed the day after birth and is shown toward all older members of the group, especially towards dominant stallions. This is a response of subordination to an aggressive behaviour or movement from the dominant stallion of the family group.
These rituals begin between mature stallions (typically around 2 years old), and allow them to confirm their social rank and create mutual respect between the dominant stallions of family groups. Examples of stallion rituals are to sniff, deposit dung and then sniff again on dung piles, parallel movements, and striking out with front hooves.
Fights contain the same actions as play, but with a much greater intensity and the ears are turned back, rather than held sideways. In general, fights are seen in stallions from 4 or 5 years old.
Characteristic of dominant stallions gathering the individuals of their group together, particularly the mares. Herding reinforces the cohesion of the group and allows stallions to maintain a distance from their rivals.