The Structure of the Groups of Misaki Horses in Toi Cape

Abstract

In Misaki pasture totaling about 500 hectares in Toi Cape of Miyazaki prefecture, 85 Misaki horses (the Japanese native horses) were in semi-wild existence in the summer of 1980. Fifteen geldings, which had been castrated in their third autumn for the purpose of the control of the numbers of stallions, are left together with other horses on the pasture. Between September 1978 and September 1980, the investigations were made on the structure of the groups of Misaki horses. Between late April and early May, horses developed stable groups consisting of one stallion, 1-7 adult mares and their foals. The organization of these groups remained permanent until October. Almost all stallions and adult mares belonged to any one of these groups during the summer. This situation observed in Misaki horses was closely similar to that of the primary groups of feral horse or the family groups of wild zebras. In winter, some of these groups separated into two or three small groups, which consisted of one stallion and 1-2 adult mares, one stallion and 1-2 adult mares plus their foals, or 1-2 adult mares and their foals. Two to three geldings occasionally joined up with the groups consisting of 1-2 adult mares and their foals or the groups consisting of one young stallion and his companions. Mature stallions, however, could never endure any geldings to remain together in their groups not only in summer but also in winter. Some groups consisting of only one or more gelding were alway observed throughout the year, some of these groups scarcely changed their organizations. The behaviours of these groups and the responses of mature stallions suggest that these groups would correspond very closely with the bachelor groups of wild equids. Some groups consisting of only 2-3 foals of 1-2 years of 1-2 years old were occasionally observed throughout the years. Some stallions or some adult mares remained solitary only for a short period. The size of the groups consisting of one stallion, one or more adult mares and their foals ranged from 3 to 13, with a mean of 6. Out of 13 groups consisting of one stallion and one or more adult mares, 7 groups consisted of one stallion and one adult mare, 5 groups consisted of one stallion and two adult mares, and one group consisted of one stallion and three adult mares. The groups consisting of one or more adult mares and their foals ranged in group size from 2 to 5, with a mean of 2.9. The mean group size consisting of geldings only was 3.2 with a range of 1-6.