After sexual maturity, female Przewalski’s horses remain in the herd, but males are driven away to live in bachelor groups before establishing or stealing their own harems.
Przewalski’s horses are sexually mature at about two years of age.
Females may remain with the herd but males are driven away after a year.
There have been sightings of young solitary stallions, a result of the leader having driven the younger and weaker males from the herd. After dispersing from their natal band at approximately 2 years of age, male Przewalski’s horses enter bachelor groups consisting of other young males and unsuccessful older stallions. When they are five years of age or older, stallions attempt to form harems of semi-permanent membership that are held year-round. They take over already established harems, steal mares from rivals, or are joined by females dispersing from their natal harem at approximately two to three years of age.