Abstract: Between 1977 and 1986, two actual rank changes and two unsuccessful attempts occurred among the mares of the Cologne herd. The stallion was at first a low-ranking individual, but attained a dominant position during the last 3 years. At this time he started to split his group and thus to affect attachment relationships among his mares. During his absence of half a year, new bonds resulted and disappeared again some months after his return. Foals were tolerated by the sire for a long time. His behaviour to young, sub-adult mares varied with the individual. Protection of sub-adult mares by adult mares against the stallion's attacks may occur. Young mares protect and guard strange foals from their very first day. Management steps to cope with social and feeding problems consisted of enlargement and adding complexity to the enclosure, the establishment of more feeding sites, building a stable and temporary removal of the stallion.