General Description of Animal and Social System

Elephants are the largest mammals on land. Male adult elephants (bulls) are larger than female adult elephants (cows). The average height of bulls is three meters and the average height of cows is two and a half meters. The average weight of bulls is 5,000 kilograms and the average weight of cows is 3,000 kilograms. Elephants have trunks that are used for drinking, feeding, object manipulation, and communication. Tusks grow larger throughout an elephant's life (Estes 1991). Elephants can live to be 66 years. However, very few elephants reach this age. The main cause of death is killing by humans (Moss 1988).
The basic social structure is the family unit (herd). The family unit is a group of related cows, normally consisting of a matriarch, her grown daughters, and their offspring (Moss 1982). A family unit typically consists of 9 to 11 members. The family unit has a rank hierarchy; rank is determined by age and size. Rank becomes apparent when there is a limited resource (Moss 1982). When the family unit has more than around ten members, it often splits into two groups. These two family units compose a bond group. Bond groups include an average of 2.5 family units. The family units in a bond group often stay close to each other and will affectionately greet each other. Due to environmental pressures, elephants sometimes form clans, groups that aggregate in an area seasonally (Estes 1991, Moss 1988). Clans typically consist of around 200 individuals (Estes 1991). There is not a close relationship between members of the clan (Moss 1988).
Male elephants gradually leave their herd at adolescence, which normally occurs when a male elephant is twelve or thirteen years old. Once leaving the family unit, young bulls often live in herds together. Young bulls play fight in order to establish a hierarchy (Moss 1982). Throughout the rest of their lives, bulls live alone or in bachelor herds. Bachelor herds normally consist of 2 to 14 members and are fluid in membership (Estes 1991).