Here, we hypothesized that aggression rates and social cohesion were correlated to adult-young ratios.
Here, we observed naturally-formed groups with various adult-young ratios and hypothesized that adult-young ratios would influence aggression rates and social cohesion of young Przewalski horses, Equus f. przewalskii.
Only long-term experimental manipulations of adult-young ratios in groups could fill this gap in our understanding.
The adult-young ratios observed in this Przewalski horse population are similar to those observed in feral horse populations (e.g. from 0.50 to 1.30 [26], [26]).
This is the first study demonstrating a correlation between adult-young ratios and aggression rates and social cohesion of young individuals in a naturalistic setting.
Aggression rates and spatial relationships varied significantly with adult-young ratios when the factor group size effect was kept constant (see methods).
This is, to our knowledge, the first study investigating the effects of adult-young ratios on aggression rates and social cohesion.
Here, we show for the first time that adult-young ratios are directly correlated to the expression of aggression and to the social cohesion of young horses in their family group, aspects that affect the social skills of young horses.
Thus, we showed that when, in a group, adult-young ratios were low, young horses were more aggressive, segregated more from adults and established tighter bonds with other young.
This therefore raises the important question of the consequences of early-stage variations of adult-young ratios on the long-term acquisition of social skills as well as on the functioning and the efficiency of groups.
We investigated the social interactions and spatial relationships of 12 one- and two-year-old Przewalski horses belonging to five families with adult-young ratios (AYR) ranging from 0.67 to 1.33.
