Hippopotamuses inhabit sub-Saharan African rivers. The population underwent considerable declines in 1990s–2000s. Numbers are currently estimated stable. Main threats are habitat loss from agricultural development, and illegal hunting for meat, hide and ivory “tusks” (which in fact are canine teeth).
■ Included in the IUCN Red List of Threatened Species in 1996, listed as Vulnerable since 2006.
■ Within EAZA, captive population data are recorded in European Studbook since 2006. The studbook is kept by Zoo Ostrava.
■ Listed in Appendix II of Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES, or Washington Convention).
Hippos spend entire day sleeping and resting in water, but they only rarely feed on aquatic plants. At dusk they go ashore to graze on short grass that is their main diet. While in water, often only eyes, nostrils and ears remain above the surface. When completely submerging, Hippo closes the slit-like nostrils and ears. Muddier water helps to protect Hippo’s skin from the sun. Hippos mark their territory with their feces, distributing them by spinning their bristled tails. Hippo dung provides nutrients from terrestrial material for aquatic invertebrates and fish.
Baby Hippos are born underwater. The calves can swim and dive before they can walk, and they nurse underwater. They often rest on their mothers’ back; that presumably gives also some protection against crocodiles while babies are still small.
Hippos weigh 1,500–3,000 kg and are among the largest land animals, being only smaller than elephants and some rhinoceros. Although bulky, barrel-shaped and short-legged, Hippos are able to run at speeds up to 30 km per hour. However, they maintain such speeds for only a few hundred metres.
■ Phylum Chordata – chordates
■ Class Mammalia – mammals
■ Order Artiodactyla – even-toed ungulates
■ Family Hippopotamidae – hippopotamuses
■ Species Hippopotamus amphibius – Hippopotamus