Elephants: Proboscidea

The female elephant, or cow, is sexually mature between the ages of twelve and fourteen and begins to reproduce shortly after that. Cows typically give birth to one calf at a time every four or five years. One of every one hundred births results in a twin delivery. The gestation period, length of pregnancy, for an elephant cow is twenty-two months. This ensures that the calf will be born during the rainy season, when grass will be plentiful for both mother and baby. Mating takes place at sixteen-week intervals year round.

Elephant cows give birth standing up, with the help of other females. Within hours, the calf will stand and take its first steps. Calves nurse, feed on their mother's milk, until they are two or three years old, sometimes longer, depending on the timing of the mother's next birth. Male calves nurse more frequently than do females, which becomes evident by the difference in size after the first few years.

Elephants have socially complex lives. The social structure is matriarchal (may-tree-ARK-ul), female-led, and the family is at the core. Each family unit has three to twenty-five members of adult females and their offspring. The females remain close throughout their lifetimes. Male elephants are typically solitary, preferring their own company to that of herds. They leave their birth families between the ages of twelve and fifteen and have no long-term bonds with them or any other elephants.

Groups are led by the older females, who make all decisions. Calves remain very close to their mothers, but all the females of the group will assist in raising the calves. Elephants are highly intelligent, and social interaction is complex. For example, within families, individuals greet one another by making sounds and touching each other with their trunks.