Though they mature between ten and twenty years of age, elephants continue growing for life. They may also maintain family relationships for life. Elephant society is matriarchal. In other words, herds are led by a female. The simplest elephant group is a singe female with one or more young.
Elephant herds merge and separate according to the seasons.
Thus, clans of fifty or more may join into larger herds after spring rains, when fresh grass is abundant, or when migrating. Only young males belong to such herds, usually being driven out when they reach puberty. Bulls may then form bachelor herds, though many males remain solitary. Females live alone very rarely, generally when they are too old to reproduce. Herds numbering in the hundreds are sometimes seen, mostly in East Africa.