A male hippo is called a Bull, while the Female is a caw and the younglings are calves. Hippos tend to live in groups, which can be as large as 100. However, a pod tends to have about 30 hippos. These groups usually have one male leader who reached that position by successfully fighting off other males.
Hippopotami are polygynous animals where one male, the group leader breeds with all the females in his group. Breeding usually occurs during the dry season (between February and August) while births tend to happen in the wet season (from October and April). However, this is not strictly seasonal, it only tends to happen more during these times of the year. So, really hippo breeding can take place at any time of the year.
Female hippos reach sexual maturity between 3 or 4 years old, but usually, don’t start mating until they are about 7 or 8 years. After giving birth, a female hippopotamus won’t ovulate for about one year and a half. This means that a female generally only has one offspring every two years. While Hippos are known to be highly aggressive and loners, the mothers are very good caregivers. They offer guidance, interaction, and learning so that their young can be strong and healthy as they mature. The females that don’t have young to care for will go through cycles where they can conceive.
Male hippopotami reach maturity at about 5 years old but won’t successfully confront other males for the right of breeding until they are much older and bigger (about 13 or 15 years old). Fights between hippos are very common during mating season and a bull won’t be able to mate until it is the dominant male of the group. The dominant bull of the herd will be around females frequently during their cycles. It usually doesn’t last for more than three days at a time.
The predominant bull searches for a mate roaming around a resting or grazing herd. He smells each caw’s ass, acting especially submissive towards the females as if he wants to avoid any kind of confrontation. The final purpose is to find a female in heat.
When he finally discovers an appropriate partner the courtship begins. He teases the female and pushes her out of the herd, persuing her into deeper waters until she snaps and tries to fight him off by clashing jaws. The Male naturally forces the female into submission and mounts her. During copulation, the female keeps the head underwater, only lifting up to breathe. It’s unclear why this happens.
When copulating the male hippo gives a wheezy honking which proclaims that mating has occurred. This is an intense time for all of the herd as the aggressive nature intensifies at this time.
How Hippos give birth?
Pregnant hippos become more aggressive and protective to anyone encountering them. Prior to birth they isolate themselves on shallow water or on land and don’t turn back to the hear a few weeks after birth.
The females give birth to their young in the water. Doing so helps the mother to conserve her energy. It also reduces the chances of the young becoming a victim of an animal on land.
The young are born after a gestation period of eight months and maturity is only achieved at about 3 and a half years. Due to this huge parental investment into each calf, normally Hippopotami only mate every other year.
How many baby hippos are born?
Almost always it is only one Hippo born but there are documented occurrences of the occasional set of twins. A female hippopotamus only has one calf every two years. A few weeks after birth, mother and youngling join schools that provide some protection against lions, crocodiles, and hyenas which are the main predators of baby hippos. Females are usually accompanied by 2 or 3 calves of different ages.
Similarly to other big mammals, hippos developed a K-type reproductive strategy. They take several years to develop and nurse only one big, well-developed calf instead of producing many undeveloped younglings many times a year.
How are Baby Hippos born?
Baby hippos are born weighing between 25 and 50 Kg and measuring about 130 cm long. They are born well developed and know instinctively how to move in the water. They have to get to the surface quickly to take a breath immediately after birth.
Since the mother Hippo often needs to be in water that is too deep for her young, you will see them riding on her back. If she stays in shallow water then the sunlight will be able to dry her skin and to sunburn.
The mother will create milk for her young to suckle from for about the first six to eight months of life. They will suckle underwater by closing their ears and nostrils during the day, and on land, in the evening as the mother looks for her own sources of food. If food is scarce some females will nurse the young for the first year of life.
Mothers and calves have a strong relationship. One can see them frequently cuddling, cleaning and other ways of showing each other affection. A big part of the attacks on humans are made by pregnant females or after birth trying to protect their calves. As Hippos live on strong social ambiance, males are usually protective over both calves and females of the herd and will also attack anything that poses a threat, humans included.
There is plenty about Hippo reproduction that we still need to learn. As we said above they mate while in the water, but since that water is often dark and murky the mating rituals can be hard to document. To make these studies even more difficult though, Hippos look very similar so it can be hard to tell if they are males or females while in the water.
In 1987 the Toledo Zoo was successfully able to film a baby Hippo being born under the water. You may be able to find a video of this amazing event online if you want to get more information about it.