Common Hippopotamus

Hippos interact with each other, but do not form close groups or bonds. Mature males are semi-solitary and territorial, presiding over a stretch of river and allowing groups of females (and non-challenging males) to live there. Females will choose where to live based on the quality of the habitat, and thus there will be larger groups in better parts of the river. Hippos are known to be friendly to each other when in water, but can be aggressive towards each other when on land, especially when feeding.

Hippos breed year-round, with peaks during the rainy season. Male hippos with better territory are more likely to be successful in finding a mate, due to the increase in probability that females will select their stretch of river to live in. Males detect receptive females through smell, before following and vocalising at her until she allows him to mate with her. The two mate underwater, with the female's nostrils often being the only visible part of her above the surface.

8 months after intercourse, the female hippopotamus will give birth, underwater, to a single baby, who will swim to the surface to take its first breath. The calves stay with their mother until they are sexually mature - between 5 and 7 years old, at which point they will leave to find their own area to live away from related individuals.