The pygmy hippopotamus is taxonomically or scientifically classified as Choreopsis liberiensis or Hexaprotodon liberiensis, as there is debate among the scientific community surrounding which scientific classification is the correct term for these creatures, though either one is acceptable. Related to the much larger common, or Nile, hippopotamus, the pygmy hippo, although far more secretive and primarily forest dwelling, shares much of the aggressive tendencies of its larger relative. Not much is known about the pygmy hippopotamus in its natural habitat due to its shy and nocturnal nature. It was not classified by the International Union for the Conservation of Nature (IUCN) as endangered until 2006. There is an active captive breeding program throughout the world that aims to prevent the extinction of this solitary, secretive mammal.
A quiet, secretive, forest-dwelling mammal, the pygmy hippopotamus is not as small as the name implies. It is, however, considerably smaller than the common hippo to which it is related, standing 2.5 feet (75 centimeters) tall and weighing around 600 pounds (275 kilograms). Despite its small stature, it can be extremely aggressive, much like its larger relative, when defending juveniles and territory, or when it feels threatened. The large, tusk-like teeth and powerful jaws can inflict a variety of serious injuries, including punctures, gores, and crush injuries. Incidents of this type involving humans are very rare in the wild, as the pygmy hippopotamus avoids human contact as much as possible.
Usually coming together only to breed, the pygmy hippopotamus tends to be a solitary creature. Females are able to bear one calf every other year, with the infant remaining with the mother for around two years. Males play no part in rearing the calf, leaving all parental responsibility to the female. Although these muscular animals are accomplished swimmers, they spend the majority of their time in the dense vegetation of the forest floor. According to the Smithsonian National Zoological Park, the pygmy hippopotamus can live up to 50 years in captivity. The majority of the information surrounding this animal comes from captive specimens because their secretive nature and potentially aggressive behavior makes field studies in the natural habitat virtually impossible.
The population of the pygmy hippo continues to decrease as time passes, prompting research on the total amount still alive in the wild. A survey conducted in 1993 estimated a total wild population of only 2000 to 3000 individuals, surviving only in isolated pockets across four West African countries. Despite this disturbing survey, they were not placed on the IUCN Red List as endangered until 2006. The IUCN states that the wild population continues to decline at an alarming rate due to civil conflicts, habitat loss, and poaching, as well as ineffectual legal protection, and farmers shooting the creatures in an attempt to reduce crop damage.
Many zoos, animal sanctuaries, and wildlife parks across the world participate in a pygmy hippopotamus breeding program. This program aims to prevent the extinction of the pygmy hippopotamus and has long-term goals of reintroducing captive bred specimens into suitable habitat, primarily in areas where they have become locally extinct. By continuing this program and naturalizing captive-bred groups in the wild over time, it is hoped that the wild population will increase to sustainable levels and the endangered species status can be lowered.