Britannica Sources used in this answer

Why do dominant male hippopotamuses control river territories?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

A hippopotamus stands at the edge of a watering hole, with several other hippos partially submerged in the water, surrounded by green vegetation in Botswana, Africa. — hippopotamus The word *hippopotamus* is Greek for “river horse,” which reflects their behavior: they are often seen basking on the banks or sleeping in the waters of rivers, lakes, and swamps across Africa. They favor shallow areas where they can sleep half-submerged, though these places can become quite crowded—as many as 150 hippos may use one pool in the dry season.

Dominant male hippopotamuses control river territories primarily to secure exclusive mating access. During the dry season, when water sources become limited and populations congregate in crowded pools, these bulls monopolize specific areas of the river to ensure they are the primary partners for the cows that aggregate there.12

A dominant male’s large size—being roughly 30 percent heavier than females—provides a significant advantage in contests against other males, allowing him to defend his territory for 12 years or more. While subordinate males are often tolerated if they do not attempt to breed, dominant bulls will aggressively defend their space against strange males during the mating season. This territorial behavior is signaled through routine displays, such as staring at rivals and using their tails to flip urine and feces in a wide arc to mark the area as occupied.12