How Long Are Elephants Pregnant? The Longest Gestation

How long is an elephant pregnancy?

The gestation period of the African bush elephant is about 22 months, or roughly 650 days. The Asian elephant has a slightly more variable pregnancy of about 18–22 months, usually close to the upper end. The African forest elephant is thought to be similar, though it is much less studied.

For comparison, a human pregnancy lasts about 9 months, a giraffe’s about 15 months and a sperm whale’s about 14–16 months. Elephants top every mammal. See the animals with the longest pregnancies for a wider comparison.

Why are elephants pregnant for so long?

The main reason is the size and development of the calf. Elephant calves are born large and well developed. They can stand and walk within hours and must keep up with a herd that travels many kilometers a day. A long pregnancy gives time for this growth.

The brain is a big part of the story. Elephants have large, complex brains, and a newborn calf’s brain already weighs about 30–40% of its adult weight, a much higher share than in a newborn human. Building such a brain inside the womb takes time. The trunk, which a calf will need for feeding, drinking and communicating, also develops before birth, though it takes many months after birth to learn to control it.

The way elephant pregnancy is maintained is also unusual. A 2012 study of elephants in zoos found that females develop several corpora lutea, small hormone-producing structures in the ovaries, around the time of conception. These produce the hormones that keep the pregnancy going for nearly two years, instead of the placenta taking over as it does in many mammals.

How do elephants mate and give birth?

Female elephants are fertile for only a few days in each estrous cycle, which lasts 14–16 weeks, one of the longest cycles known. Females signal readiness with scent and low rumbles, and bulls in musth travel widely to find them. Most matings in African bush elephants happen in the rainy season, so many calves are born in a later rainy season when food is plentiful.

Birth usually takes place with the mother standing, often surrounded by members of her family. Relatives gather close, rumbling and touching the newborn with their trunks. A newborn calf weighs about 90–120 kg (200–265 lb) and stands around 85–90 cm (3 ft) at the shoulder. It can usually stand within about 30 minutes and walk soon after. Twins are rare.

How often do elephants have calves?

Because pregnancy is so long and calves depend on milk for years, elephants breed slowly. A female usually gives birth only every four to five years. In good years with plenty of food the gap can be shorter; in droughts it gets longer.

Most females have their first calf in their early to mid teens, and they can keep breeding into their 50s. This slow breeding rate is one reason elephant populations take a long time to recover from poaching. Read more in Are elephants endangered?

How do herds help raise a calf?

A calf is born into a family. For the first three months it lives only on its mother’s milk, and it keeps suckling for at least two years, often longer, while it learns to feed itself. During this time, older sisters, aunts and cousins help look after it. This is called allomothering, and the helpers, or allomothers, are usually young females between about 2 and 12 years old.

Allomothers stay close to the calf, comfort it, help it up steep riverbanks and defend it from danger. Studies have found that calves in families with more allomothers have better chances of survival, and the young females gain experience they will use with their own calves.

How do you know if an elephant is pregnant?

Elephants carry their calves without an obvious change in shape for much of the pregnancy, because the belly is already huge. In zoos, keepers confirm pregnancy with regular hormone tests and ultrasound scans. In the wild, researchers often only know a female was pregnant when she appears with a new calf, although they can sometimes detect pregnancy hormones in dung samples.

Breeding elephants in zoos has long been difficult. Bulls in musth are hard to manage, and the long estrous cycle makes it tricky to time matings. Modern hormone monitoring, which tracks a female’s cycle week by week, and artificial insemination have helped zoos in Europe and North America produce more calves. Even so, keepers must plan for each birth almost two years in advance, and the calf will need years of care from its mother and her companions.