Factors affecting the harem formation process by young Misaki feral stallions.

Abstract

For the past 12 years, a study was conducted in the Misaki area (southern Kyushu Island, Japan) to investigate young males form new harems, how they acquire the mares and the factors affecting the process of new harem formation. Young males formed new harems between the ages of 3.8 and 7.6 yr, and 93% of these new harem groups were formed at the beginning of the breeding season. The most common way (87%) for young males to form a new harem was by acquiring wandering mares which had separated from their groups, whereas 13% stole unstable mares from established bands. The fact that all young males obtained harems the new at an early age, with an average age of 5.2 yr (n = 15) could be explained high female biased sex ratio (3:1), and great number of wandering mares per stallion (2.5:1). At the time new harem groups were formed, aggression, fighting or such behavior as active herding or driving mares was not observed among stallions because the "unstable" mares were most likely to be abducted by stallions.