A male elephant will be able to mate when they are about ten to fourteen years of age, while a female will be ready to mate between the ages of twelve to fifteen. Elephants can mate throughout the year, and the bull, or male elephant, usually mates with more than one female. After they mate, they do not stay together. If the food supply is plentiful, they will mate more frequently.
Heightened sexuality occurs during a period referred to as "musth." The elephant has two temporal glands on each side of its head, and once a year, for several months, it releases a substance with a strong odor. During this period the elephant becomes very aggressive, and sexually aroused. Elephants will also mate during non-musth periods, yet during this time they tend to be more sexually active.
The female elephant will carry her unborn calf in her body for 18 to 24 months. Normally an elephant has a single birth, yet occasionally there are twin births. The African calf can weight anywhere between 250 pounds to 320 pounds at birth, while the Asiatic elephant newborn weighs in around 220 pounds. The baby elephant can walk within hours after birth. The young calf nourishes itself on the mother's milk, and will not start grazing on grass until two to six years of age.
When held in captivity, the diagnosing and monitoring of pregnant female elephants is typically done by observing the progesterone hormone. When pregnant the level of progesterone is elevated, which helps to sustain the pregnancy. Another way to determine if an elephant is pregnant is to measure the serum prolactin after the fifth or sixth month into the term. A little less than a week before going into labor the progesterone level will drop. This helps to signal the veterinarians working with the facility of the impending birth.
Although female elephants typically are not ready to mate until they are at least 12 years old, there has been controversy over Sydney, Australia's zoo for mating a female elephant at the age of nine. When the nine-year-old's pregnancy was announced, it received outrage from the animal right's community. According to the Born Free Foundation, female elephants ten-years or older have a 76 percent success rate of delivering a healthy calf, as opposed to those under 10 years, which experience a 50 percent risk of infant mortality during the first year.