Harem’s and Bulls
Hippos practice a harem system where bulls occupy well-defended territories that contain nursery herds of females and their young. Pods of hippo can range from 2-200 animals but typically contain 7-15. Bulls are especially grumpy and do not tolerate one another and often even young bulls are slashed on the head and shoulders with their sharp teeth. Dominant bulls typically display their status through wide-mouth yawns that exhibit their formidable canine teeth – instruments of defence not feeding.
These are continually sharpened by abrasion with the pair on the opposite jaw and can easily penetrate the 6 cm thick hide of a contender and do some serious damage to him. Only the most serious opponents will engage in combat as this can lead to death. Usually, they signal their disapproval of one another with showers of dung sent scattering by a paddled tail-action. Territories are marked on land in this way too, especially favoured pathways leading from the water.
The iconic and impressive honking of hippo bulls serves to advertise territory and ward off would-be intruders. Hippos do however produce other sounds from growls to grunts to squeals. These probably fulfil an array of social uses.
Hippo bulls have little tact when it comes to mating. There is no courtship ritual to speak of and the male will simply locate an oestrus female by parading through the pod smelling their rear ends. A female on heat is then chased into the water where the bull will force her prostrate even snapping at her should she come up for breath!
Calves are born in the water albeit shallow enough so it doesn’t have to swim to breath. They are able to walk and swim within minutes. They suckle underwater, which is made possible by the folding ears and closing nostrils that also allow them not to drown when submerged normally. The calf pinches the female’s teat between its tongue and the palate of its mouth. Females are fiercely protective of their babies even against other hippos including the bull.
Hippos have enormous, powerful muzzles that can stretch wide open. Their lower canines are modified into huge tusks that grow continuously and may reach 30-50 cm long. A hippo will defend itself and it’s young with these well-adapted weapons and is well able to bite a 3 m crocodile in half.
By Megan Emmett