ecology Hippos are semiaquatic and require enough water to immerse in, while being close to grass. They prefer relatively still waters with gently sloping shores, though male hippos may also be found in very small numbers in more rapid waters with rocky slopes. Hippos mostly live in freshwater habitat, but can be found in estuaries. Hippos spend most the day in water to stay cool and hydrated. Just before night begins, they leave the water to foraging on land. Like most herbivores, hippos will consume a variety of plants if presented with them in captivity, but their diet in nature consists almost entirely of grass, with only minimal consumption of aquatic plants. A hippo will travel per night, eating around of grass. By dawn, they are back in the water. On occasion, hippos have been filmed eating carrion, usually near the water. There are other reports of meat-eating and even cannibalism and predation. The stomach anatomy of lacks adaptions to carnivory, and meat-eating is likely caused by lack of nutrients or just an abnormal behaviour. Because of their size and their habit of taking the same paths to feed, hippos can have a significant impact on the land across which they walk, keeping the land clear of vegetation and depressing the ground. Over prolonged periods, hippos can divert the paths of swamps and channels. By defecating in the water, the animals also appear to pass on microbes from their gut, affecting the biogeochemical cycle. Social interaction It is challenging to study the interaction of bulls and cows because hippos are not sexually dimorphic, so cows and young bulls are almost indistinguishable in the field. Hippo pods fluctuate but can contain over 100 hippos. Although they lie close together, adults develop almost no social bonds. Males establish territories in water but not land, and these may range in lakes and in rivers. Territories are abandoned when the water dries up. The bull has breeding access to all the cows in his territory. Younger bachelors are allowed to stay as long as they defer to him. A younger male may challenge the old bull for control of the territory. Within the pods, the hippos tend to segregate by sex and status. Bachelor males lounge near other bachelors, females with other females, and the territorial male is on his own. When hippos emerge from the water to graze, they do so individually. Hippos