The hippopotamus is semi-aquatic, inhabiting rivers and lakes
where territorial bulls preside over a stretch of river and
groups of 5 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 grass.
While hippopotamuses rest near each other in the water, grazing
is a solitary activity and hippos are not territorial on land.