In every herd, horses are quick to find out who is the leader and which place each horse gets in the hierarchy. This ranking is usually determined by horses moving each other: ‘whoever moves, dictates.’ But as soon as the horses know what place they have in the group, there are few serious conflicts among themselves. 

In a study published in the ‘Journal of Animal Science’, Czech researchers looked at factors that could influence the hierarchy in a herd of foals. Specific attention was paid to the rank the mothers had in the herd and whether this was decisive for the rank the foals were given in the herd. 

The researchers looked at eight groups of mares with lactating foals, a total of 66 mother-foal pairs. A few years later, they looked at the same foals again, who were now 3 years old. These were divided into four groups. 

They found that older foals, physically larger than the younger foals, had a higher rank in the herd. This was independent of the rank the dams had. 

The dam’s upbringing therefore did not seem to have any influence on the foal’s rank. But it was striking that foals with the same mother, who were born one year apart, seemed to have the same place in the ranking as a three-year-old. This suggests that there might be an unknown effect of the mare on the social status of her foal. 

Older, larger foals that were the tallest in their herd had the highest position in the hierarchy. These foals were also weaned first and were therefore the first to be placed in the yearling group. That is why they kept their social rank. 

In this study, it emerged that age, size and the time that a horse had lived in the herd were the most important factors in determining the hierarchy.