Pygmy hippopotamus: Difference between revisions

Pygmy Hippopotamus
Conservation status
	Endangered
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Artiodactyla
Family:	Hippopotamidae
Genus:	Choeropsis
Species:	C. liberiensis
Binomial name
	Choeropsis liberiensis; (Morton, 1849)
Subspecies
	C. l. liberiensis; C. l. heslopi;
	Range map

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The Pygmy Hippopotamus (Choeropsis liberiensis or Hexaprotodon liberiensis) is a large mammal native to the forests and swamps of western Africa (the species name means "of Liberia", as this is where the vast majority lives). The pygmy hippo is reclusive and nocturnal. It is one of only two extant species in the hippopotamidae family, the other being its much larger cousin the common hippopotamus.

The pygmy hippopotamus displays many terrestrial adaptations, but like the common hippopotamus, the smaller species is semi-aquatic and relies on proximity of water to keep its skin moisturized and its body temperature cool. The pygmy hippo may mate and give birth in water or on land. The pygmy hippo is herbivorous, feeding on whatever ferns, broad-leaved plants, grasses and fruits it finds in the forests.

The pygmy hippopotamus is a difficult animal to study in the wild, because it is a rare, nocturnal, forest creature, that lives primarily in countries with a great degree of civil strife. The pygmy hippo lives a mostly solitary life; sometimes seen in pairs or threesomes, but never large pods like the common hippopotamus. They are not known to be territorial.

Pygmy hippos were unknown outside of West Africa until the 19th century. They were not introduced to zoos until the early 20th century. Pygmy hippos breed well in zoos, and most research on the animal comes from zoo specimens. The survival of the species in captivity is more assured than in the wild. The World Conservation Union estimates that there are less than 3,000 pygmy hippos remaining in the wild.^[1] Pygmy hippos are primarily threatened by loss of habitat, as forests are logged and converted to farm land, but also vulnerable to poaching, hunting, natural predators and war.

Taxonomy and origins

Nomenclature of the pygmy hippopotamus reflects that of the hippopotamus. The plural form is pygmy hippopotami (hippopotamuses is also accepted as a plural form by the OED, or pygmy hippos for short). A male pygmy hippopotamus is known as a bull, a female as a cow, and a baby as a calf.

The pygmy hippopotamus is a member of the family Hippopotamidae where it is classified as a member of either the Choeropsis (meaning like a hog) or Hexaprotodon (meaning six front teeth) genus. Hippopotamidae are sometimes known as Hippopotamids. Sometimes the sub-family Hippopotaminae is used. Further, some taxonomists group hippopotami and anthracotheres in the super-family Anthracotheroidea or Hippopotamoidea.

The taxonomy of the genus of the pygmy hippopotamus is disputed. Samuel G. Morton initially classified the animal as Hippopotamus minor, but later determined it was distinct enough to warrant its own genus. In 1977 Coryndon proposed that the pygmy hippopotamus was closely related to Hexaprotodon, a genus that consisted of prehistoric hippos that mostly lived in Asia.^[3] This assertion was mostly accepted, until a thorough examination of the phylogeny of hippopotamidae in 2005 caused Boisserie to assert that the pygmy hippopotamus was a distinct genus, and returned the pygmy hippopotamus to Choeropsis.^[4] Either way, the pygmy hippo is the only extant member of its genus.^[4]^[3]

Nigerian subspecies

All research on living pygmy hippos is from Choeropsis liberiensis liberiensis (or Hexaprotodon liberiensis liberiensis) from Guinea, Sierra Leone, Liberia and Côte d'Ivoire. A second subspecies, C. liberiensis heslopi (or H. liberiensis heslopi) lived in Nigeria into at least the 20th century.^[5]

The Nigerian pygmy hippopotamus ranged until recently in the Niger River Delta, especially near Port Harcourt. It is believed to be extinct. The subspecies was separated by over 1800 km and the Dahomey Gap, a region of desert that divides the forest regions of West Africa. The subspecies is named after I.R.P. Heslop, who claimed in 1945 to have shot a pygmy hippo in the Niger Delta region and collected several skulls. He estimated that perhaps no more than 30 pygmy hippos remained in the region.^[6]

Heslop sent four pygmy hippopotamus skulls he collected in Nigeria to G.B. Corbet, who classified the skulls as belonging to a separate subspecies based off consistent variations in the proportions of the skulls.^[7] The pygmy hippos have been seen or shot in Rivers State, Imo State and Bayelsa State, Nigeria.^[5]

Evolution

The most recent research into the origins of hippopotamidae suggests that hippos and whales shared a common semi-aquatic ancestor that branched off from other Artiodactyls around 60 mya.^[8]^[9] This hypothesized ancestor likely split into two branches around 54 mya.^[10] One branch would evolve into cetaceans, possibly beginning with the proto-whale Pakicetus from 52 mya and other early whale ancestors, known as Archaeoceti, which eventually underwent aquatic adaptation into the almost completely aquatic cetaceans.^[11]

The other branch became the anthracotheres, a large family of four-legged beasts, the earliest of whom in the Late Eocene would have resembled skinny hippopotami with comparatively small and narrow heads. All branches of the anthracotheres, except that which evolved into Hippopotamidae, became extinct without leaving any descendants.^[8]

A rough evolution can be traced, however, from Eocene and Oligocene species: Anthracotherium and Elomeryx to the Miocene anthracotheres Merycopotamus and Libycosaurus. Merycopotamus, Libycosaurus and all hippopotamids can be considered to form a clade, with Libycosaurus being more closely related to hippos. Their common ancestor would have lived in the Miocene, about 20 mya. The last species of anthracotheres became extinct during the pliocene.^[12]

Hippopotamids are therefore deeply nested within the family Anthracotheriidae. The oldest known hippopotamid is the genus Kenyapotamus which lived in Africa from Expression error: Unexpected round operator Expression error: Unexpected < operator mya. Kenyapotamus, though known only through fragmentary fossils, was similar in size to the pygmy hippopotamus. The Hippopotamidae are believed to have evolved in Africa, and while at one point the species spread across Asia and Europe, no hippopotami have ever been discovered in the Americas. From Expression error: Unexpected round operator Expression error: Unexpected < operator mya an ancestor to the modern hippopotamus and to Hexaprotodon, the Archaeopotamus lived in Africa and the Middle East.^[4]

While the fossil record of hippos is still poorly understood, the two modern genera, Hippopotamus and Choeropsis, may have diverged as far back as 8 mya. The ancestral form of the pygmy hippopotamus may be the genus Saotherium. Saotherium and Choeropsis are significantly more basal than Hippopotamus and Hexaprotodon, and thus more closely resemble the ancestral species of hippos.^[4]^[12]

Prehistoric species

Several species of small hippopotamidae have become extinct. Many islands of the Mediterranean had hippo populations, such as the Cretan Dwarf Hippopotamus (Hippopotamus creutzburgi) of Crete, the Sicilian Hippopotamus (Hippopotamus pentlandi) of Sicily, or the Maltese Hippopotamus (Hippopotamus melitensis) of Malta. These species, though comparable in size to the pygmy hippopotamus, are considered dwarf hippopotamuses. They are likely descended from a full-sized species of European Hippopotamus, and reached their small size through the evolutionary process of insular dwarfism which is common on islands.^[13]

Another species of note is the Cyprus Dwarf Hippopotamus (Hippopotamus minor) which existed on the island of Cyprus, possibly into the Holocene. The relationship between the Cyprus Dwarf Hippopotamus and other hippos is poorly understood, and some consider the species to belong to a distinct genus Phanourios.^[4]

As many as three species of hippos have become extinct on the island of Madagascar. At least one of these Malagasy Hippopotamuses, Choeropsis madagascariensis or the Madagascan Pygmy Hippopotamus is believed to be a member of the same genus as the extant pygmy hippopotamus.^[14]^[15]

Description

The pygmy hippo is only half as tall as the hippopotamus and weighs less than 1/4 as much as its larger cousin. Adult pygmy hippos stand about 75–83 cm (30–32 inches) high at the shoulder, are 150–177 cm (59–70 inches) in length and weigh 180–275 kilograms (400-600 pounds).^[5] Their lifespan in captivity ranges from 30 to 55 years, though it is unlikely that they live this long in the wild.^[16]^[5]

A pygmy hippopotamus resting at the Louisville Zoo. The skull of a pygmy hippo has less pronounced orbits and nostrils than a common hippopotamus.

The skin is greenish-black or brown, shading to a creamy gray on the lower body. Their skin is very similar to the common hippo's, with a thin epidermis over a dermis that is several centimeters thick. Pygmy hippos have the same unusual sweat as common hippos, that gives a pinkish tinge to their bodies, and is sometimes described as "blood sweat" though the secretion is neither sweat nor blood. The highly alkaline substance is believed to have antiseptic and sunscreening properties. The skin of hippos dries out quickly and cracks, which is why both species of hippos spend so much time in water.^[5]

The skeleton of the pygmy hippopotamus is more gracile than that of the common hippopotamus. The common hippo's back is parallel with the ground; the pygmy hippo's back slopes forward, a likely adaptation to pass more easily through dense forest vegetation. Proportionally, the pygmy hippos legs and neck are longer and its head smaller. The orbits and nostrils of a pygmy hippo are much less pronounced, an adaptation from spending less time in deep water (where pronounced orbits and nostrils help the common hippo breathe and see). The feet of pygmy hippos are narrower, but the toes are more spread out and have less webbing, to assist in walking on the forest floor.^[16] Despite adaptations to a more terrestrial life than the common hippopotamus, pygmy hippos are still more aquatic than the rest of the even-toed ungulates. The ears and nostrils of pygmy hippos have strong muscular valves to aid going underwater, and the skin physiology is dependent on the availability of water.^[5]^[17]

Behavior

The behavior of the pygmy hippo differs from the common hippo in many ways. Much of its behavior is more similar to that of a tapir, though this is an effect of convergent evolution.^[17] While the common hippopotamus is gregarious, pygmy hippos live either alone or in small groups, typically a mated pair or a mother and calf. Pygmy hippos tend to ignore each other rather than fight when they meet. Field studies have estimated that male pygmy hippos range over 185 Hectares, while the range of a female is between 40–60 ha.^[5]

Pygmy hippos spend most of the day hidden in rivers. They will rest in the same spot for several days in a row, before moving to a new spot. At least some pygmy hippos make use of dens or burrows that form in river banks. It is unknown if the pygmy hippos help create these dens, or how common it is to use them. Though a pygmy hippo has never been observed burrowing, other Artiodactyls, such as warthogs are burrowers.^[5]

Diet

Like the common hippopotamus, the pygmy hippo emerges from the water at dusk to feed. It relies on game trails to travel through dense forest vegetation. It marks the trails by spreading feces by vigorously waving its tale while defecating. The pygmy hippo spends about six hours a day foraging for food.^[5]

Pygmy hippos are herbivorous. They do not eat aquatic vegetation to a significant extent and rarely eat grass because it is uncommon in the thick forests they inhabit. The bulk of a pygmy hippo's diet consists of ferns, broad-leaved plants, and fruits that have fallen to the forest floor. The wide variety of plants pygmy hippos have been observed eating suggests that they will eat any plants available. This diet is of higher quality than that of the common hippopotamus.^[5]

Reproduction

A study of breeding behavior in the wild has never been conducted; the artificial conditions of captivity may cause the observed behavior of pygmy hippos in zoos to differ from natural conditions. Sexual maturity for the pygmy hippopotamus occurs at between three to five years.^[17] The youngest reported age for giving birth is a pygmy hippo at the zoo in Basel, Switzerland which bore a calf at 3 years and 3 months.^[5] The oestrus cycle of a female pygmy hippo lasts an average of 35.5 days, with the oestrus itself lasting between 24-48 hours.^[1]^[18]

Pygmy hippos consort for mating, but the duration of the relationship is unknown. In zoos they breed as monogamous pairs. Copulation can take place on land or in the water, and a pair will mate one to four times during an oestrus period. In captivity, pygmy hippos have been conceived and born in all months of the year.^[17] The gestation period ranges from 190-210 days, and usually a single young is born, though twins are known to occur.^[5]

The common hippopotamus gives birth and mates only in the water, but pygmy hippos mate and give birth on both land and water. Young pygmy hippos can swim almost immediately. At birth, pygmy hippos weigh 4.5–6.2 kg (9.9–13.7 lbs) with males weighing about .25 kg (.55 lbs) more than females. Pygmy hippos are fully weaned between 6-8 months of age; before weaning they do not accompany their mother when she leaves the water to forage, but instead hide in the water by themselves. The mother returns to the hiding spot about three times a day and calls out for the calf to suckle. Suckling occurs with the mother lying on her side.^[5]

Distribution

The vast majority of pygmy hippos live in Liberia with smaller populations, mostly clustered around the Liberian border, in Côte d'Ivoire, Guinea and Sierra Leone. In the past, the range of the pygmy hippo was not much different, but populations were less fragmented. Pygmy hippos live exclusively in forested regions.^[1]

In Liberia, pygmy hippo populations occur in many forests. The largest population lives in Liberia's largest protected region Sapo National Park. Populations have been reported in Grand Kru County, Grand Cape Mount County, Grand Bassa County, Grand Gedeh County, Lofa County, Maryland County, Nimba County and Sinoe County. Studies of these populations, however, have been complicated by civil strife, such as the First Liberian Civil War and the Second Liberian Civil War. In Côte d'Ivoire the pygmy hippo ranges in several forests, including those in the Taï National Park. In Guinea the pygmy hippopotamuses live in the Reserve de Ziama on the border with Liberia. In Sierra Leone, several small populations exist—in the Gola Forest, on Tiwai Island in the Moa River and in the Loma Mountains.^[1]^[5]

The World Conservation Union's 1993 Action Plan estimated a population of between 2,000 and 3,000 pygmy hippos in the wild, with most in Liberia. The smallest population is that of Sierra Leone, estimated in 1993 to be only around 100. Due to deteriorating conditions in Liberia, the IUCN Red List estimated in 2006 that this number had likely declined, particularly due to loss of habitat.^[1]

Conservation

The biggest threat to the remaining pygmy hippopotamus population in the wild is loss of habitat. The forests in which pygmy hippos live have been subject to logging, settling and conversion to agriculture, with little efforts made to make logging sustainable. As forests shrink, the populations become more fragmented, leading to less genetic diversity in the potential mating pool.^[1]

Because of their reclusive lifestyle they are not a target of subsistence hunting, though they are hunted opportunistically by bush hunters. Their meat is said to be of excellent quality, like that of a wild boar; unlike the common hippo, the pygmy hippos teeth have no value.^[17] The effects of West Africa's civil strife on the pygmy hippopotamus are unknown, but unlikely to be positive.^[1] Adult common hippos have no natural predators, but the pygmy hippopotamus is capable of being killed by leopards, pythons and crocodiles. The frequency with which this occurs, however, is unknown.^[5]

The Pygmy Hippopotamus was identified as one of the top-10 "focal species" in 2007 by the Evolutionarily Distinct and Globally Endangered (EDGE) project.^[19] EDGE identifies species that are evolutionarily distinct and need better protection to prevent extinction. The pygmy hippo was placed in the top-10 along with Attenborough's long-beaked echidna, Hispaniolan solenodon, Bactrian camel, Yangtze River dolphin, Slender loris, Hirola antelope, Golden-rumped elephant shrew, Bumblebee bat, and the Long-eared jerboa.^[20]

Although threatened in the wild, pygmy hippos breed freely in zoos. Between 1970 and 1991 the population of pygmy hippos born in captivity more than doubled. The survival of the species in zoos is more certain than the survival of the species in the wild.^[21] ^[16] In captivity, the pygmy hippo lives from 42-55 years, longer than in the wild.^[5] Since 1919, only 41 percent of pygmy hippos born in zoos have been male.^[18]

The first pygmy hippo was brought to Europe in 1873 after being captured in Sierra Leone by a member of the British Colonial Service but died shortly after arrival. Pygmy hippos were successfully introduced to Europe in 1911. They were first shipped to Germany and then to the Bronx Zoo in New York City where they also thrived.^[5]^[17]

In 1927, Harvey Firestone of Firestone Tires presented Billy the pygmy hippo to U.S. President Calvin Coolidge. Coolidge donated Billy to the Smithsonian National Zoological Park and according to the zoo, is a common ancestor to most pygmy hippos in U.S. zoos today.^[16] ^[22]

History and folklore

While the common hippopotamus was known to Europeans since antiquity, the pygmy hippopotamus was unknown outside of its range in West Africa until the 19th century. Due to their nocturnal, forested existence, they were poorly known within their range as well. In Liberia the animal was traditonally known as a water cow.^[17]

Early field reports of the animal misidentified it as a wild hog. Several skulls of the species were sent to the American natural scientist Samuel G. Morton, during his residency in Monrovia, Liberia. Morton first described the species in 1843. The first complete specimens were collected as part of a comprehensive investigation of Liberian fauna in the 1870s and 1880s by Dr. Johann Büttikofer. The specimens were taken to the Natural History Museum in Leiden, Netherlands.^[17]

Several folktales have been collected about the pygmy hippopotamus. One tale says that pygmy hippos carry a shining diamond in their mouths to help travel through thick forests at night; by day the pygmy hippo has a secret hiding place for the diamond, but if a hunter catches a pygmy hippo at night the diamond can be taken. Villagers sometimes believed that baby pygmy hippos do not nurse but rather lick secretions off the skin of the mother.^[17]

References

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Template:IUCN2006
^ "ITIS on Hexaprotodon liberiensis". Integrated Taxonomic Information System. Retrieved 2004-08-11.
^ ^a ^b "The taxonomy and nomenclature of the Hippopotamidae (Mammalia, Artiodactyla) and a description of two new fossil species". Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen. 80 (2): 61–88. 1977.
^ ^a ^b ^c ^d ^e Boisserie, Jean-Renaud (2005). "The phylogeny and taxonomy of Hippopotamidae (Mammalia: Artiodactyla): a review based on morphology and cladistic analysis". Zoological Journal of the Linnean Society. 143: 1–26. Retrieved 2007-06-01.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q Eltringham, S. Keith. "The Hippos". ISBN 085661131X.
^ "Pigs, Peccaries and Hippos Status Survey and Action Plan". World Conservation Union status survey. 1993. Retrieved 2007-05-22.
^ Corbet, G.B. (1969). "The taxonomic status of the Pygmy hippopotamus, Choeropsis liberiensis, from the Niger Delta". Journal of Zoology. 158: 387–394.
^ ^a ^b "Scientists find missing link between the dolphin, whale and its closest relative, the hippo". Science News Daily. 2005-01-25. Retrieved 2007-06-18.
^ Gatesy, J. "More DNA support for a Cetacea/Hippopotamidae clade: the blood-clotting protein gene gamma-fibrinogen". Molecular Biology and Evolution. 14: 537–543.
^ Ursing, B.M. (1998). "Analyses of mitochondrial genomes strongly support a hippopotamus-whale clade". Proceedings of the Royal Society. 265 (1412): 2251. {{cite journal}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)
^ Boisserie, Jean-Renaud (2005). "The position of Hippopotamidae within Cetartiodactyla". Proceedings of the National Academy of Sciences. 102 (5): 1537–1541. Retrieved 2007-06-09. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
^ ^a ^b Boisserie, Jean-Renaud (2005). "Origins of Hippopotamidae (Mammalia, Cetartiodactyla): towards resolution". Zoologica Scripta. 34 (2): 119–143. Retrieved 2007-06-01. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
^ Petronio, C. (1995): Note on the taxonomy of Pleistocene hippopotamuses. Ibex 3: 53-55. PDF fulltext
^ Harris, J.M. (1991). "Family Hippopotamidae". Koobi Fora Research Project. Vol. 3. The Fossil Ungulates: Geology, Fossil Artiodactyls and Paleoenvironments. Clarendon Press, Oxford: 31–85.
^ Oliver, W.L.R. (1995). "Taxonomy and Conservation Status of the Suiformes — an Overview" (PDF). IBEX Journal of Mountain Ecology.
^ ^a ^b ^c ^d "Pygmy Hippo fact sheet". Smithsonian National Zoological Park. Retrieved 2007-05-22.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Robinson, Phillip T. River Horses and Water Cows. Hippo Specialist Group of the World Conservation Union Retrieved on 2007-07-30.
^ ^a ^b Zschokke, Samuel (2002). "Distorted Sex Ratio at Birth in the Captive Pygmy Hippopotamus, Hexaprotodon Liberiensis". Journal of Mammalogy. 83 (3): 674–681.
^ "Protection for 'weirdest' species". BBC. 2007-01-16. Retrieved 2007-05-22.
^ "Hexaprotodon liberiensis". EDGE Species. Retrieved 2007-07-31.
^ Eltringham, S. Keith (1993). "Pigs, Peccaries and Hippos Status Survey and Action Plan". IUCN.
^ Jablonski, Nina G. (2004). "The hippo's tale: how the anatomy and physiology of Late Neogene Hexaprotodon shed light on Late Neogene environmental change". Quaternary International. 117: 119–123. {{cite journal}}: External link in |title= (help)

External links

[Redlist-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Template:IUCN2006

[2] "ITIS on Hexaprotodon liberiensis". Integrated Taxonomic Information System. Retrieved 2004-08-11.

[Coryndon-3] "The taxonomy and nomenclature of the Hippopotamidae (Mammalia, Artiodactyla) and a description of two new fossil species". Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen. 80 (2): 61–88. 1977.

[Linnean-4] Boisserie, Jean-Renaud (2005). "The phylogeny and taxonomy of Hippopotamidae (Mammalia: Artiodactyla): a review based on morphology and cladistic analysis". Zoological Journal of the Linnean Society. 143: 1–26. Retrieved 2007-06-01.

[The_Hippos-5] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q Eltringham, S. Keith. "The Hippos". ISBN 085661131X.

[Action-6] "Pigs, Peccaries and Hippos Status Survey and Action Plan". World Conservation Union status survey. 1993. Retrieved 2007-05-22.

[Corbet-7] Corbet, G.B. (1969). "The taxonomic status of the Pygmy hippopotamus, Choeropsis liberiensis, from the Niger Delta". Journal of Zoology. 158: 387–394.

[ScienceNews-8] "Scientists find missing link between the dolphin, whale and its closest relative, the hippo". Science News Daily. 2005-01-25. Retrieved 2007-06-18.

[DNA-9] Gatesy, J. "More DNA support for a Cetacea/Hippopotamidae clade: the blood-clotting protein gene gamma-fibrinogen". Molecular Biology and Evolution. 14: 537–543.

[Genomes-10] Ursing, B.M. (1998). "Analyses of mitochondrial genomes strongly support a hippopotamus-whale clade". Proceedings of the Royal Society. 265 (1412): 2251. {{cite journal}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)

[Cetartiodactyla-11] Boisserie, Jean-Renaud (2005). "The position of Hippopotamidae within Cetartiodactyla". Proceedings of the National Academy of Sciences. 102 (5): 1537–1541. Retrieved 2007-06-09. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)

[Origins-12] Boisserie, Jean-Renaud (2005). "Origins of Hippopotamidae (Mammalia, Cetartiodactyla): towards resolution". Zoologica Scripta. 34 (2): 119–143. Retrieved 2007-06-01. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)

[Taxonomy_of_Pleistocene-13] Petronio, C. (1995): Note on the taxonomy of Pleistocene hippopotamuses. Ibex 3: 53-55. PDF fulltext

[Harris-14] Harris, J.M. (1991). "Family Hippopotamidae". Koobi Fora Research Project. Vol. 3. The Fossil Ungulates: Geology, Fossil Artiodactyls and Paleoenvironments. Clarendon Press, Oxford: 31–85.

[IBEX-15] Oliver, W.L.R. (1995). "Taxonomy and Conservation Status of the Suiformes — an Overview" (PDF). IBEX Journal of Mountain Ecology.

[National_Zoo_on_pygmy_hippos-16] "Pygmy Hippo fact sheet". Smithsonian National Zoological Park. Retrieved 2007-05-22.

[Robinson-17] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Robinson, Phillip T. River Horses and Water Cows. Hippo Specialist Group of the World Conservation Union Retrieved on 2007-07-30.

[Distort-18] Zschokke, Samuel (2002). "Distorted Sex Ratio at Birth in the Captive Pygmy Hippopotamus, Hexaprotodon Liberiensis". Journal of Mammalogy. 83 (3): 674–681.

[19] "Protection for 'weirdest' species". BBC. 2007-01-16. Retrieved 2007-05-22.

[Edge-20] "Hexaprotodon liberiensis". EDGE Species. Retrieved 2007-07-31.

[21] Eltringham, S. Keith (1993). "Pigs, Peccaries and Hippos Status Survey and Action Plan". IUCN.

[Tale-22] Jablonski, Nina G. (2004). "The hippo's tale: how the anatomy and physiology of Late Neogene Hexaprotodon shed light on Late Neogene environmental change". Quaternary International. 117: 119–123. {{cite journal}}: External link in |title= (help)

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@@ Line 47: / Line 47: @@
 ===Evolution===
+[[Image:Bothriogenys_fraasi.JPG|thumb|right|200px|''[[Arsinoitherium]]'' (top) and ''Bothriogenys fraasi'' (bottom). [[Anthracothere]]s like Bothriogenys resembled pygmy hippos and are among their likely ancestors.]]
 The most recent research into the origins of hippopotamidae suggests that hippos and whales shared a common semi-aquatic ancestor that branched off from other Artiodactyls around {{mya|60|mya}}.<ref name="ScienceNews">{{Cite web | title = Scientists find missing link between the dolphin, whale and its closest relative, the hippo | date = 2005-01-25 | accessdate = 2007-06-18 | url = http://www.sciencenewsdaily.org/story-2806.html | work = Science News Daily}}</ref><ref name="DNA">{{Cite journal | url = http://mbe.oxfordjournals.org/cgi/content/abstract/14/5/537 | title = More DNA support for a Cetacea/Hippopotamidae clade: the blood-clotting protein gene gamma-fibrinogen | author = Gatesy, J. | journal = [[Molecular Biology and Evolution]] | volume = 14 | pages = 537-543}}</ref> This hypothesized ancestor likely split into two branches around {{mya|54|mya}}.<ref name="Genomes">{{Cite journal | title = Analyses of mitochondrial genomes strongly support a hippopotamus-whale clade | volume = 265 | issue = 1412 | year = 1998 | pages = 2251 | journal = [[Proceedings of the Royal Society]] | author = Ursing, B.M. | coauthor = U. Arnason}}</ref>  One branch would [[Evolution of cetaceans|evolve into cetaceans]], possibly beginning with the proto-whale ''[[Pakicetus]]'' from {{mya|52|mya}} and other early whale ancestors, known as [[Archaeoceti]], which eventually underwent [[aquatic adaptation]] into the almost completely aquatic [[cetacea]]ns.<ref name="Cetartiodactyla">{{cite journal |last=Boisserie |first=Jean-Renaud |coauthors= Fabrice Lihoreau and Michel Brunet |year= 2005 |month= February|title= The position of Hippopotamidae within Cetartiodactyla|journal= [[Proceedings of the National Academy of Sciences]] |volume= 102 |issue= 5|pages= 1537-1541|url= http://www.pnas.org/cgi/content/full/102/5/1537|accessdate= 2007-06-09}}</ref>
-[[Image:Bothriogenys_fraasi.JPG|thumb|left|200px|''[[Arsinoitherium]]'' (top) and ''Bothriogenys fraasi'' (bottom). [[Anthracothere]]s like Bothriogenys resembled pygmy hippos and are among their likely ancestors.]]
 The other branch became the [[anthracotheriidae|anthracothere]]s, a large family of four-legged beasts, the earliest of whom in the [[Eocene|Late Eocene]] would have resembled skinny hippopotami with comparatively small and narrow heads.  All branches of the anthracotheres, except that which evolved into Hippopotamidae, became extinct without leaving any descendants.<ref name="ScienceNews"/>
@@ Line 58: / Line 58: @@
 While the fossil record of hippos is still poorly understood, the two modern genera, ''Hippopotamus'' and ''[[Choeropsis]]'', may have diverged as far back as {{mya|8|mya}}.  The ancestral form of the pygmy hippopotamus may be the genus ''[[Saotherium]]''.  ''Saotherium'' and ''Choeropsis'' are significantly more [[Basal (phylogenetics)|basal]] than ''Hippopotamus'' and ''Hexaprotodon'', and thus more closely resemble the ancestral species of hippos.<ref name="Linnean"/><ref name="Origins"/>
+[[Image:Hippopotamus cruetzburgi.JPG|200px|thumb|left|The [[Cretan Dwarf Hippopotamus]] (''H. creutzburgi'') was similar in size to a pygmy hippopotamus, but more closely related to the common hippopotamus.]]
 ===Prehistoric species===
-[[Image:Hippopotamus cruetzburgi.JPG|200px|thumb|The [[Cretan Dwarf Hippopotamus]] (''H. creutzburgi'') was similar in size to a pygmy hippopotamus, but more closely related to the common hippopotamus.]]
 Several species of small hippopotamidae have become extinct.  Many islands of the Mediterranean had hippo populations, such as the [[Cretan Dwarf Hippopotamus]] (''Hippopotamus creutzburgi'') of [[Crete]], the [[Sicilian Hippopotamus]] (''Hippopotamus pentlandi'') of [[Sicily]], or the [[Maltese Hippopotamus]] (''Hippopotamus melitensis'') of [[Malta]].  These species, though comparable in size to the pygmy hippopotamus, are considered dwarf hippopotamuses.  They are likely descended from a full-sized species of [[European Hippopotamus]], and reached their small size through the evolutionary process of [[insular dwarfism]] which is common on islands.<ref name = "Taxonomy of Pleistocene"> '''Petronio''', C. (1995): Note on the taxonomy of Pleistocene hippopotamuses. ''Ibex'' '''3''': 53-55. [http://www.mountainecology.org/IBEX3/pdf/Art_Capitolo1/note_taxonomy_pleistocene.pdf PDF fulltext]</ref>
@@ Line 65: / Line 65: @@
 As many as three species of hippos have become extinct on the island of [[Madagascar]].  At least one of these [[Malagasy Hippopotamus]]es, ''[[Choeropsis madagascariensis]]'' or the [[Madagascan Pygmy Hippopotamus]] is believed to be a member of the same genus as the extant pygmy hippopotamus.<ref name="Harris">{{Cite journal | author = Harris, J.M. | year = 1991 | pages = 31–85 | title = Family Hippopotamidae | journal = Koobi Fora Research Project. Vol. 3. The Fossil Ungulates: Geology, Fossil Artiodactyls and Paleoenvironments | publisher = Clarendon Press, Oxford}}</ref><ref name="IBEX">{{Cite journal | author = Oliver, W.L.R. | title = Taxonomy and Conservation Status of the Suiformes — an Overview | year = 1995 | url = http://www.mountainecology.org/IBEX3/pdf/Art_Capitolo1/Taxonomy_Conservation.pdf | journal = IBEX Journal of Mountain Ecology}}</ref>
+<br clear="both" />
 == Description ==
 The pygmy hippo is only half as tall as the hippopotamus and weighs less than 1/4 as much as its larger cousin.  Adult pygmy hippos stand about 75–83 cm (30–32 inches) high at the shoulder, are 150–177 cm (59–70 inches) in length and weigh 180–275 kilograms (400-600 pounds).<ref name="The Hippos"/>  Their lifespan in captivity ranges from 30 to 55 years, though it is unlikely that they live this long in the wild.<ref name="National Zoo on pygmy hippos"/><ref name="The Hippos"/>
+[[Image:ZooPygmyHippo.jpg|thumb|200px|A pygmy hippopotamus resting at the [[Louisville Zoo]].  The skull of a pygmy hippo has less pronounced [[Orbit (anatomy)|orbits]] and [[nostril]]s than a common hippopotamus.]]
 The skin is greenish-black or brown, shading to a creamy gray on the lower body.  Their skin is very similar to the common hippo's, with a thin [[epidermis]] over a [[dermis]] that is several centimeters thick.  Pygmy hippos have the same unusual sweat as common hippos, that gives a pinkish tinge to their bodies, and is sometimes described as "blood sweat" though the secretion is neither sweat nor blood.  The highly [[alkaline]] substance is believed to have antiseptic and sunscreening properties.  The skin of hippos dries out quickly and cracks, which is why both species of hippos spend so much time in water.<ref name="The Hippos"/>
-[[Image:ZooPygmyHippo.jpg|thumb|200px|A pygmy hippopotamus resting at the [[Louisville Zoo]].  The skull of a pygmy hippo has less pronounced [[Orbit (anatomy)|orbits]] and [[nostril]]s than a common hippopotamus.]]
 The skeleton of the pygmy hippopotamus is more gracile than that of the common hippopotamus.  The common hippo's back is parallel with the ground; the pygmy hippo's back slopes forward, a likely [[adaptation]] to pass more easily through dense forest vegetation.  Proportionally, the pygmy hippos legs and neck are longer and its head smaller.  The [[Orbit (anatomy)|orbits]] and [[nostril]]s of a pygmy hippo are much less pronounced, an adaptation from spending less time in deep water (where pronounced orbits and nostrils help the common hippo breathe and see).  The feet of pygmy hippos are narrower, but the toes are more spread out and have less webbing, to assist in walking on the forest floor.<ref name="National Zoo on pygmy hippos"/>  Despite adaptations to a more terrestrial life than the common hippopotamus, pygmy hippos are still more aquatic than the rest of the [[even-toed ungulate]]s.  The ears and nostrils of pygmy hippos have strong muscular valves to aid going underwater, and the skin physiology is dependent on the availability of water.<ref name="The Hippos"/><ref name=Robinson/>
-==Distribution==
-The vast majority of pygmy hippos live in [[Liberia]] with smaller populations, mostly clustered around the Liberian border, in [[Côte d'Ivoire]], [[Guinea]] and [[Sierra Leone]].  In the past, the range of the pygmy hippo was not much different, but populations were less fragmented.  Pygmy hippos live exclusively in forested regions.<ref name="Redlist"/>
-In Liberia, pygmy hippo populations occur in many forests.  The largest population lives in Liberia's largest protected region [[Sapo National Park]].  Populations have been reported in [[Grand Kru County]], [[Grand Cape Mount County]], [[Grand Bassa County]], [[Grand Gedeh County]], [[Lofa County]], [[Maryland County]], [[Nimba County]] and [[Sinoe County]].  Studies of these populations, however, have been complicated by civil strife, such as the [[First Liberian Civil War]] and the [[Second Liberian Civil War]].  In [[Côte d'Ivoire]] the pygmy hippo ranges in several forests, including those in the [[Taï National Park]].  In [[Guinea]] the pygmy hippopotamuses live in the [[List of biosphere reserves in Guinea|Reserve de Ziama]] on the border with Liberia.  In [[Sierra Leone]], several small populations exist&mdash;in the Gola Forest, on [[Tiwai Island]] in the [[Moa River]] and in the [[Loma Mountains]].<ref name="Redlist"/><ref name="The Hippos"/>
-[[Image:Tiwai Island River.jpg|thumb|250px|A small population of pygmy hippos lives in the dense forests on [[Tiwai Island]] in [[Sierra Leone]].]]
-The [[World Conservation Union]]'s 1993 Action Plan estimated a population of between 2,000 and 3,000 pygmy hippos in the wild, with most in Liberia.  The smallest population is that of Sierra Leone, estimated in 1993 to be only around 100.    Due to deteriorating conditions in Liberia, the [[IUCN Red List]] estimated in 2006 that this number had likely declined, particularly due to loss of habitat.<ref name="Redlist"/>
-=== Conservation ===
-The biggest threat to the remaining pygmy hippopotamus population in the wild is loss of habitat.  The forests in which pygmy hippos live have been subject to logging, settling and conversion to agriculture, with little efforts made to make logging sustainable.  As forests shrink, the populations become more fragmented, leading to less genetic diversity in the potential mating pool.<ref name="Redlist"/>
-Because of their reclusive lifestyle they are not a target of subsistence hunting, though they are hunted opportunistically by bush hunters.  Their meat is said to be of excellent quality, like that of a wild boar; unlike the common hippo, the pygmy hippos teeth have no value.<ref name=Robinson/>  The effects of West Africa's civil strife on the pygmy hippopotamus are unknown, but unlikely to be positive.<ref name="Redlist"/>  Adult common hippos have no natural predators, but the pygmy hippopotamus is capable of being killed by [[leopard]]s, [[python]]s and [[crocodile]]s.  The frequency with which this occurs, however, is unknown.<ref name="The Hippos"/>
-The Pygmy Hippopotamus was identified as one of the top-10 "focal species" in 2007 by the [[EDGE Species|Evolutionarily Distinct and Globally Endangered (EDGE)]] project.<ref>{{Cite news | title = Protection for 'weirdest' species | url = http://news.bbc.co.uk/2/hi/science/nature/6263331.stm | date = 2007-01-16 | accessdate = 2007-05-22 | work = [[BBC]]}}</ref>  EDGE identifies species that are evolutionarily distinct and need better protection to prevent extinction.  The pygmy hippo was placed in the top-10 along with [[Attenborough's long-beaked echidna]], [[Hispaniolan solenodon]], [[Bactrian camel]], [[Yangtze River dolphin]], [[Slender loris]], [[Hirola antelope]], [[Golden-rumped elephant shrew]], [[Bumblebee bat]], and the [[Long-eared jerboa]].<ref name=Edge>{{Cite web | url = http://www.edgeofexistence.org/species/species_info.asp?id=21 | title = Hexaprotodon liberiensis | work = [[EDGE Species]] | accessdate = 2007-07-31}}</ref>
 ==Behavior==
-[[Image:2006 09 09 Hipopotam ubt.jpeg|right|thumb|200px|A pygmy hippopotamus rests in the water to help prevent his skin from cracking.]]
 The behavior of the pygmy hippo differs from the common hippo in many ways.  Much of its behavior is more similar to that of a [[tapir]], though this is an effect of [[convergent evolution]].<ref name=Robinson/>  While the common hippopotamus is gregarious, pygmy hippos live either alone or in small groups, typically a mated pair or a mother and calf.  Pygmy hippos tend to ignore each other rather than fight when they meet.  Field studies have estimated that male pygmy hippos range over 185 [[Hectare]]s, while the range of a female is between 40–60 ha.<ref name="The Hippos"/>
+[[Image:2006 09 09 Hipopotam ubt.jpeg|left|thumb|200px|A pygmy hippopotamus rests in the water to help prevent his skin from cracking.]]
 Pygmy hippos spend most of the day hidden in rivers.  They will rest in the same spot for several days in a row, before moving to a new spot.  At least some pygmy hippos make use of [[Lair|dens]] or [[burrow]]s that form in river banks.  It is unknown if the pygmy hippos help create these dens, or how common it is to use them.  Though a pygmy hippo has never been observed burrowing, other Artiodactyls, such as [[warthogs]] are burrowers.<ref name="The Hippos"/>
@@ Line 98: / Line 84: @@
 Like the common hippopotamus, the pygmy hippo emerges from the water at dusk to feed.  It relies on game trails to travel through dense forest vegetation.  It marks the trails by spreading feces by vigorously waving its tale while defecating.  The pygmy hippo spends about six hours a day foraging for food.<ref name="The Hippos"/>
-[[Image:bristol.zoo.pygmy.hippo.arp.jpg|thumb|200px|left|A pygmy hippo at the [[Bristol Zoo]] in [[England]].  Pygmy hippos will eat almost any sort of plant available.]]
 Pygmy hippos are [[herbivore|herbivorous]].  They do not eat aquatic vegetation to a significant extent and rarely eat grass because it is uncommon in the thick forests they inhabit.  The bulk of a pygmy hippo's diet consists of [[fern]]s, [[dicotyledons|broad-leaved plants]], and [[fruit]]s that have fallen to the forest floor.  The wide variety of plants pygmy hippos have been observed eating suggests that they will eat any plants available.  This diet is of higher quality than that of the common hippopotamus.<ref name="The Hippos"/>
 ===Reproduction===
+[[Image:Pygmy Hippopotamus with the young.jpg|right|200px|thumb|A baby pygmy hippopotamus stands near its parent at a zoo in [[Jihlava]], [[Czech Republic]].]]
 A study of breeding behavior in the wild has never been conducted; the artificial conditions of captivity may cause the observed behavior of pygmy hippos in zoos to differ from natural conditions.  Sexual maturity for the pygmy hippopotamus occurs at between three to five years.<ref name=Robinson/>  The youngest reported age for giving birth is a pygmy hippo at the zoo in [[Basel]], [[Switzerland]] which bore a calf at 3 years and 3 months.<ref name="The Hippos"/>  The [[oestrus cycle]] of a female pygmy hippo lasts an average of 35.5 days, with the oestrus itself lasting between 24-48 hours.<ref name="Redlist"/><ref name=Distort/>
-[[Image:Pygmy Hippopotamus with the young.jpg|right|250px|thumb|A baby pygmy hippopotamus stands near its parent at a zoo in [[Jihlava]], [[Czech Republic]].]]
 Pygmy hippos consort for mating, but the duration of the relationship is unknown.  In zoos they breed as monogamous pairs.  Copulation can take place on land or in the water, and a pair will mate one to four times during an oestrus period.  In captivity, pygmy hippos have been conceived and born in all months of the year.<ref name=Robinson/>  The gestation period ranges from 190-210 days, and usually a single young is born, though twins are known to occur.<ref name="The Hippos"/>
 The common hippopotamus gives birth and mates only in the water, but pygmy hippos mate and give birth on both land and water.  Young pygmy hippos can swim almost immediately.  At birth, pygmy hippos weigh 4.5–6.2&nbsp;kg (9.9–13.7&nbsp;lbs) with males weighing about .25 kg (.55 lbs) more than females.  Pygmy hippos are fully [[wean]]ed between 6-8 months of age; before weaning they do not accompany their mother when she leaves the water to forage, but instead hide in the water by themselves.  The mother returns to the hiding spot about three times a day and calls out for the calf to suckle.  Suckling occurs with the mother lying on her side.<ref name="The Hippos"/>
+==Distribution==
-== Pygmy hippos and humans ==
-[[Image:Pygmy hippo edinburgh zoo 2004 SMC.jpg|200px|thumb|According to West African folktales, pygmy hippos carry a diamond in their mouth at night, and if caught the hunter can keep the diamond.]]
+[[Image:Tiwai Island River.jpg|thumb|200px|left|A small population of pygmy hippos lives in the dense forests on [[Tiwai Island]] in [[Sierra Leone]].]]
+The vast majority of pygmy hippos live in [[Liberia]] with smaller populations, mostly clustered around the Liberian border, in [[Côte d'Ivoire]], [[Guinea]] and [[Sierra Leone]].  In the past, the range of the pygmy hippo was not much different, but populations were less fragmented.  Pygmy hippos live exclusively in forested regions.<ref name="Redlist"/>
-[[Image:Hipopotam karÅ‚owaty.jpg|thumb|200px|A pygmy hippopotamus at a zoo in [[Poznań]], [[Poland]].]]
-While the common hippopotamus was known to Europeans since [[antiquity]], the pygmy hippopotamus was unknown outside of its range in West Africa until the 19th century.  Due to their nocturnal, forested existence, they were poorly known within their range as well.  In Liberia the animal was traditonally known as a ''water cow''.<ref name=Robinson/>
+In Liberia, pygmy hippo populations occur in many forests.  The largest population lives in Liberia's largest protected region [[Sapo National Park]].  Populations have been reported in [[Grand Kru County]], [[Grand Cape Mount County]], [[Grand Bassa County]], [[Grand Gedeh County]], [[Lofa County]], [[Maryland County]], [[Nimba County]] and [[Sinoe County]].  Studies of these populations, however, have been complicated by civil strife, such as the [[First Liberian Civil War]] and the [[Second Liberian Civil War]].  In [[Côte d'Ivoire]] the pygmy hippo ranges in several forests, including those in the [[Taï National Park]].  In [[Guinea]] the pygmy hippopotamuses live in the [[List of biosphere reserves in Guinea|Reserve de Ziama]] on the border with Liberia.  In [[Sierra Leone]], several small populations exist&mdash;in the Gola Forest, on [[Tiwai Island]] in the [[Moa River]] and in the [[Loma Mountains]].<ref name="Redlist"/><ref name="The Hippos"/>
-Early field reports of the animal misidentified it as a [[wild hog]].  Several skulls of the species  were sent to the American natural scientist [[Samuel G. Morton]], during his residency in [[Monrovia]], [[Liberia]].  Morton first described the species in 1843.  The first complete specimens were collected as part of a comprehensive investigation of Liberian fauna in the 1870s and 1880s by Dr. Johann Büttikofer.  The specimens were taken to the [[Natural History Museum, Leiden|Natural History Museum]] in [[Leiden]], [[Netherlands]].<ref name=Robinson/>
+The [[World Conservation Union]]'s 1993 Action Plan estimated a population of between 2,000 and 3,000 pygmy hippos in the wild, with most in Liberia.  The smallest population is that of Sierra Leone, estimated in 1993 to be only around 100.    Due to deteriorating conditions in Liberia, the [[IUCN Red List]] estimated in 2006 that this number had likely declined, particularly due to loss of habitat.<ref name="Redlist"/>
-Several folktales have been collected about the pygmy hippopotamus.  One tale says that pygmy hippos carry a shining diamond in their mouths to help travel through thick forests at night; by day the pygmy hippo has a secret hiding place for the diamond, but if a hunter catches a pygmy hippo at night the diamond can be taken.  Villagers sometimes believed that baby pygmy hippos do not nurse but rather lick secretions off the skin of the mother.<ref name=Robinson/>
+== Conservation ==
+The biggest threat to the remaining pygmy hippopotamus population in the wild is loss of habitat.  The forests in which pygmy hippos live have been subject to logging, settling and conversion to agriculture, with little efforts made to make logging sustainable.  As forests shrink, the populations become more fragmented, leading to less genetic diversity in the potential mating pool.<ref name="Redlist"/>
+Because of their reclusive lifestyle they are not a target of subsistence hunting, though they are hunted opportunistically by bush hunters.  Their meat is said to be of excellent quality, like that of a wild boar; unlike the common hippo, the pygmy hippos teeth have no value.<ref name=Robinson/>  The effects of West Africa's civil strife on the pygmy hippopotamus are unknown, but unlikely to be positive.<ref name="Redlist"/>  Adult common hippos have no natural predators, but the pygmy hippopotamus is capable of being killed by [[leopard]]s, [[python]]s and [[crocodile]]s.  The frequency with which this occurs, however, is unknown.<ref name="The Hippos"/>
+The Pygmy Hippopotamus was identified as one of the top-10 "focal species" in 2007 by the [[EDGE Species|Evolutionarily Distinct and Globally Endangered (EDGE)]] project.<ref>{{Cite news | title = Protection for 'weirdest' species | url = http://news.bbc.co.uk/2/hi/science/nature/6263331.stm | date = 2007-01-16 | accessdate = 2007-05-22 | work = [[BBC]]}}</ref>  EDGE identifies species that are evolutionarily distinct and need better protection to prevent extinction.  The pygmy hippo was placed in the top-10 along with [[Attenborough's long-beaked echidna]], [[Hispaniolan solenodon]], [[Bactrian camel]], [[Yangtze River dolphin]], [[Slender loris]], [[Hirola antelope]], [[Golden-rumped elephant shrew]], [[Bumblebee bat]], and the [[Long-eared jerboa]].<ref name=Edge>{{Cite web | url = http://www.edgeofexistence.org/species/species_info.asp?id=21 | title = Hexaprotodon liberiensis | work = [[EDGE Species]] | accessdate = 2007-07-31}}</ref>
-=== In captivity ===
 Although threatened in the wild, pygmy hippos breed freely in zoos.  Between 1970 and 1991 the population of pygmy hippos born in captivity more than doubled.  The survival of the species in zoos is more certain than the survival of the species in the wild.<ref>{{Cite web| url = http://www.iucn.org/themes/ssc/sgs/pphsg/APchap3-3.htm | title = Pigs, Peccaries and Hippos Status Survey and Action Plan | work = [[World Conservation Union|IUCN]] | date = 1993 | author = Eltringham, S. Keith}}</ref>
 <ref name="National Zoo on pygmy hippos">{{Cite web | url = http://nationalzoo.si.edu/Animals/AsianElephants/factpygmyhippo.cfm | title = Pygmy Hippo fact sheet | work = [[Smithsonian National Zoological Park]] | accessdate = 2007-05-22}}</ref>  In captivity, the pygmy hippo lives from 42-55 years, longer than in the wild.<ref name="The Hippos">{{Cite book| title = "The Hippos" | author = Eltringham, S. Keith | isbn=085661131X}}</ref>  Since 1919, only 41 percent of pygmy hippos born in zoos have been male.<ref name=Distort>{{Cite journal | journal = [[Journal of Mammalogy]] | volume = 83 | number = 3 | pages = 674–681 | year = 2002 | title = Distorted Sex Ratio at Birth in the Captive Pygmy Hippopotamus, Hexaprotodon Liberiensis | author = Zschokke, Samuel}}</ref>
@@ Line 124: / Line 114: @@
 The first pygmy hippo was brought to [[Europe]] in 1873 after being captured in Sierra Leone by a member of the British Colonial Service but died shortly after arrival.  Pygmy hippos were successfully introduced to Europe in 1911.  They were first shipped to Germany and then to the [[Bronx Zoo]] in [[New York City]] where they also thrived.<ref name="The Hippos"/><ref name=Robinson>Robinson, Phillip T. [http://moray.ml.duke.edu/projects/hippos/Pygmy_Text.doc River Horses and Water Cows]. ''[http://moray.ml.duke.edu/projects/hippos/index.html Hippo Specialist Group of the World Conservation Union]''  Retrieved on 2007-07-30.</ref>
-In 1927, [[Harvey Firestone]] of [[Firestone Tire and Rubber Company|Firestone Tires]] presented [[Billy (pygmy hippo)|Billy the pygmy hippo]] to U.S. President [[Calvin Coolidge]].  Coolidge donated Billy to the [[Smithsonian National Zoological Park]] and according to the zoo, is a common ancestor to most pygmy hippos in U.S. zoos today.<ref name="National Zoo on pygmy hippos" />
+In 1927, [[Harvey Firestone]] of [[Firestone Tire and Rubber Company|Firestone Tires]] presented [[Billy (pygmy hippo)|Billy the pygmy hippo]] to U.S. President [[Calvin Coolidge]]. Coolidge donated Billy to the [[Smithsonian National Zoological Park]] and according to the zoo, is a common ancestor to most pygmy hippos in U.S. zoos today.<ref name="National Zoo on pygmy hippos" />
 <ref name=Tale>{{Cite journal | journal = [[Quaternary International]] | volume = 117 | year = 2004 | pages = 119–123 | title = [http://dx.doi.org/10.1016/S1040-6182(03)00121-6 The hippo’s tale: how the anatomy and physiology of Late Neogene Hexaprotodon shed light on Late Neogene environmental change] | author = Jablonski, Nina G.}}</ref>
+== History and folklore ==
+While the common hippopotamus was known to Europeans since [[antiquity]], the pygmy hippopotamus was unknown outside of its range in West Africa until the 19th century.  Due to their nocturnal, forested existence, they were poorly known within their range as well.  In Liberia the animal was traditonally known as a ''water cow''.<ref name=Robinson/>
+Early field reports of the animal misidentified it as a [[wild hog]].  Several skulls of the species  were sent to the American natural scientist [[Samuel G. Morton]], during his residency in [[Monrovia]], [[Liberia]].  Morton first described the species in 1843.  The first complete specimens were collected as part of a comprehensive investigation of Liberian fauna in the 1870s and 1880s by Dr. Johann Büttikofer.  The specimens were taken to the [[Natural History Museum, Leiden|Natural History Museum]] in [[Leiden]], [[Netherlands]].<ref name=Robinson/>
+Several folktales have been collected about the pygmy hippopotamus.  One tale says that pygmy hippos carry a shining diamond in their mouths to help travel through thick forests at night; by day the pygmy hippo has a secret hiding place for the diamond, but if a hunter catches a pygmy hippo at night the diamond can be taken.  Villagers sometimes believed that baby pygmy hippos do not nurse but rather lick secretions off the skin of the mother.<ref name=Robinson/>
 == References ==