The hippopotamus is semiaquatic mammal, inhabiting rivers, lakes and mangrove swamps, where territorial bulls preside over a stretch of river and groups of five to 30 females and young. During the day, they remain cool by staying in the water or mud; reproduction and childbirth both occur in water. They emerge at dusk to graze on grasses. While hippopotamuses rest near each other in the water, grazing is a solitary activity and hippos are not territorial on land.
The African buffalo or Cape buffalo, is a large African bovine. It is not closely related to the slightly larger wild Asian water buffalo, and its ancestry remains unclear.