Portrait of a resting Hippopotamus (hippopotamus amphibius) in the Saint Lucia estuary, Kwa-Zulu Natal, South Africa. Although these animals are gregarious, they are not social animals and often fight amongst each other. Although these animals are mainly herbivorous, they account for many deaths of humans in Africa as they are predominantly active at night and forage on land often killing unexpected humans who encounter them in poorly lit rural areas.