Hippopotamus, Hippopotamus amphibius,
& Pygmy Hippopotamus, Choeropsis liberiensis 2001, revised 2011 |  |
Common hippopotamus (Hippopotamus amphibius)
|
(Boisserie 2008) (Boisserie et al 2005) (Harris et al. 2008) (Kingdon 1979) (Lihoreau et al 2006) (Meester & Setzer 1971)
(Stuenes 1989) (Wilson & Reeder 1992)
Describer (Date): Linnaeus (1758) Systema Naturae Tenth ed. Vol 1. p 74, Laurentii Salvii Stockholm. Described animals from the Nile River in Egypt.
Kingdom: Animal
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla* (Even-toed hoofed animals: includes pigs, sheep goats, cattle, deer)
Family: Hippopotamidae
Genus: Choeropsis
Species: Choeropsis liberiensis (Pygmy Hippopotamus)
Subspecies: C. l. liberiensis
Subspecies: C. l. heslopi
Genus: Hippopotamus
Species: Hippopotamus amphibius (Common Hippopotamus)
Species: Hippopotamus madagascariensis (extinct dwarf hippo from Madagascar)
Species: Hippopotamus lemerlei (extinct dwarf hippo from Madagascar)
*New anatomical and DNA evidence on the relationship between Artiodactyla (even-toed ungulates) and Cetacea (whales and dolphins) recently led to a merging of the two orders into a new group, Cetartiodactyla (Montgelard, 1997; reviewed in Kulemzina, 2009). As of October 2012, experts had not agreed on whether to define Cetartiodactyla as an official taxonomic order that would replace Artiodactyla and Cetacea. Some continue to list hippopotamuses in the order Artiodactyla (Franklin, 2011) or use the term Cetartiodactyla without defining it as an order (IUCN, 2008).
Taxonomy, Phylogeny, and Historical Records
- Scientific name
- Hippopotamus: Hippos from Greek for horse, potamos from Greek for "river or rushing water"
- Choeropsis: Meaning from the Greek: "having the appearance of a young pig" (Parker 2010)
- Common name (for Common or River Hippo)
- Common Hippopotamus, River Hippopotamus, or Nile Hippopotamus; In Afrikaan: seekoei (sea cow).
- Numerous tribal names including: Kiboko (Kiswahlili), Olmakau (Masai), Jir (Somali).
- German: Nilpferd (Nile horse)
- Spanish: Hipopotamos
- French: Hippopotame.
- Closest living relatives to hippos are whales. (Boisserie et al 2005)
- To reflect this close relationship, families of whales and families of artiodactyls should be grouped together
- The new taxonomic Order, Cetartiodactyla, reflects both numerous DNA and fossil studies
- Pigs (Tayassuidae) are not close relatives of hippos, contrary to many taxonomies based on morphology. (Boisserie et al 2005)
- Oldest Cetartiodactyla fossils are members of the family
Anthracotheriidae from Asia dating to around 41 million years ago
(Eocene).
- Anthracotheres diversified to Africa in Eocene times.
- By Miocene times (around 15.7 million years ago), the earliest hippos probably arose from Anthracotheres.
(Lihoreau et al 2006)
(Behrensmeyer et al 2002) (Boisserie et al 2005)- Anthracotheres + hippos most likely form a sister taxa to whales
- Share a common ancestor with whales
- Earliest hippos lived in Africa. (Harris et al. 2008)
- Fossil hippos from Pliocene and Pleistocene times are numerous and diverse. (Harris et al. 2008)
- By Ice Age Pleistocene times (1.8 million to 13,000 years ago) hippos inhabited England and Europe, Asia, and Africa.
- Pollen studies show that the hippos were associated with swamp forests along riverbanks. (Ravazzi et al 2009)
- Around 3500 B.C. hippos were apparently maintained in a private zoo
along with elephants and baboons in the ancient
Egyptian city of Hierakonpolis. (Rose 2010) - Extinct dwarf hippo remains found in Madagascar and Cyprus date to 1,000 years ago, or less.
(MacPhee & Flemming 1999) (Stuenes 1989)- May have been hunted to extinction by humans. (MacPhee & Burney 1991)
- Two extinct dwarf species on Madagascar had similar ecological specializations as living Pygmy and
Common Hippo today: one more aquatic, one more terrestrial - Hippos arrived in Madagascar presumably by rafting across the ocean between this island and Africa.
- Pygmy Hippos have recently had their taxonomy and phylogeny reassessed (Boisserie & Kingdon 2005)
- The correct scientific name for the genus should be Choeropsis
- Commonly used Hexaprotodon now applies only to extinct hippos
(Lewison & Oliver 2008) (Oliver 1993)
- Common Hippos Geographic Distribution: Sub-saharan Africa;
- Native to Angola; Benin; Botswana; Burkina Faso; Burundi; Cameroon; Central African Republic; Chad; Congo; Congo, The Democratic Republic of the; Côte d'Ivoire; Equatorial Guinea; Ethiopia; Gabon; Gambia; Ghana; Guinea; Guinea-Bissau; Kenya; Liberia; Malawi; Mali; Mozambique; Namibia; Niger; Nigeria; Rwanda; Senegal; Sierra Leone; Somalia; South Africa; Sudan; Swaziland; Tanzania, United Republics of Togo; Uganda; Zambia; Zimbabwe
- Locally extinct in Algeria, Egypt, Mauritania, Liberia
- Latest records for Nile Delta and Egypt - early 1800's
- Common Hippos Habitats: Most abundant in estuaries and lower sections of rivers
- In recent times, have been found in reservoirs.
- Absent in rainforests, except nr. large rivers
- Frequently wander from water in rainy season.
- Water habitat must be deep enough for submersion with nearby grassland for foraging.
- Can survive in muddy wallows, but must have permanent access to water in dry season because of complex skin physiology. (Will crack if exposed to air for long periods).
- Pygmy Hippos Geographic Distribution: Mainly in Liberia; only overlaps with Common Hippos in upper reaches of rivers in Ivory Coast
- Pygmy Hippos Habitats: Forests; these hippos ecologically similar to tapirs
 |
 |
Common hippo distribution.
Adapted from www.d-maps.com according to IUCN fact sheet. Click here or on map for detailed inset. |
Pygmy hippo distribution.
Adapted from www.d-maps.com according to IUCN fact sheet. Click here or on map for detailed inset. |
(Estes 1991) (Eltringham 1999) (Kingdon 1979, 1997) (Nowak 1991)
Height: Common Hippo 150-165 cm (4.9-5.4 ft)
Pygmy Hippo about half the height of Common Hippo
Weight: Common Hippo males up to 1,475 kg (3253 lb); Females 1,360 kg (655-2,344 kg).
Pygmy Hippo about a sixth the weight of the larger Common Hippo
Length: Common Hippo males 300-505 (9.8-16.6 ft), females 290-430 cm (9.5-14 ft)
Pygmy Hippo males 157 cm ( in ) , females up to 150 cm ( in)
Tail: Common Hippo 28-35 cm (11-14 in) flattened laterally and bristled
Pygmy Hippo 16 cm (6.3 in)
General
- Measurements are subject to much regional variation.
- Comparison of the two species:
- Pygmy Hippo is smaller overall
- Pygmy Hippo's head proportionally smaller and rounder
- Pygmy Hippo's neck is proportionally longer
- Pygmy Hippos skeleton more lightly built
- Pygmy Hippo's back slopes forward, Common Hippo's is straight
- Eyes of Pygmy Hippos less bulging, more on side of head (less aquatic in habits)
- Some sexual
dimorphism.
- Muzzle is noticeably bigger in males and jowl area more developed.
- "Tusks" are twice as long in males
- Body is barrel shaped, legs short
- Brain case small
- Jaws hinged far to the back, allowing enormous gape of 150° (humans have only 45°)
- Multi-chambered non-ruminating stomach; no caecum or gallbladder
- Females have 2 mammae.
- Four functional toes with wide splay
- Nail-like hooves on ends of toes
- Head is adapted for submersion:
- Eyes slightly periscoped and aligned on top of head along with ears and nostrils
- Nostrils close before submersion.
- Ears fold into recessed area to close underwater
- Jaw and ear similarities to cetaceans that are helpful in underwater hearing
(Barklow 1997) (Vaughan et al 2011)
- Lower jaw bone (dentary) has flattened dish shaped area
- Middle ear is suspended by ligaments
- Fatty tissue connects middle ear to the dentary
- Water-born sounds in dolphins travel from jaw bone to fat tissue to middle ear bones
- Hippos may be hearing underwater sounds when lower jaw is below water.
- Bones are dense (osteosclerotic) as seen in many aquatic and semiaquatic mammals
- Partial webbing on feet may aid in stabilization while bottom walking
- Pygmy Hippo feet little or no webbing
- Many muscle groups and tendons in hind limbs are different from those of other artiodactyls (Fisher et al 2010)
- Flexor and extensor muscles allow control and splaying of side digits of foot
- Other artiodactyls: reduced lateral digits that don't bear weight and can't be splayed
- For hippos, being able to splay digits is a good adaptation for walking in water on soft river bottoms
- Other distinguishing features of hippo limb muscles are for powerful propulsion through water, but not swimming.
- Muscles present represent "primitive" condition in artiodactyls; reflect ancient divergence of hippos from other artiodactyls
- Additional aquatic adaptations of feet probably not seen, since hippos also need to walk on land.
- Well-developed muscles for constricting airways in the lung's bronchioles also found in whales. (Cowan et al 1967)
 |
 |
Hippos display tusk-like canines sharpened
by wear against their upper teeth. To the front of a pygmy hippo jaw are a single pair of incisors. |
Common hippos with their wider jaws
have two or three pairs of incisors. |
- Canines and incisors enormously enlarged and continuously growing
- Tusk-like canines are used for fighting
- Male canines can grow to 50 cm (1.5 ft) and are usually twice the length of female's
- Kept sharpened by constant vertical wear against the shorter upper canines
- Incisors used for digging
- Jaws capable of 150 degree gape (slightly less in pygmy hippo)
- Simple low-crowned molars in back for chewing
- Dental formulas differ in two species:
- Larger Common Hippo has 2-3 pairs of incisors; very wide mouth
- Smaller Pygmy Hippo, 1 pair incisors; mouth less wide
- Common Hippo Purple-gray or slate brown
- Lower surfaces and skin around eyes and ears tend to be brownish pink
- Pygmy Hippo Greenish black above, grey on sides, greyish-white below
- Scantily covered with fine hairs except for short bristles on head, back and tail
- No scent or sweat glands, but mucous glands secrete a thick, oily red
fluid "blood sweat"
(Galasso & Pichierri 2009)
- Dries like lacquer and serves to protect the thin epidermis against water loss, sunburn and infection
- Hippos suffer many bite wounds from fighting, but red pigment's ("hipposudoric acid") antibiotic properties
inhibit pathogenic bacteria
- Epidermis (outer horny layer) is uniformly thin
- The endodermis varies from 5-6 cm on back and rump to < 1cm (.4 in) on head and belly
- Albino hippos are common. (Pitman 1962)
(Coughlin & Fish 2009) (Eltringham 1999, 2001) (Estes 1991) (Kingdon 1979) (Klingel 1990, 1995) (Lang et al 1990)
(Mosepele et al 2009) (Oliver 1993) (Roberts 1951)
 |
Pygmy hippos often spend time resting and feeding on land.
Their behavior in the wild is still largely unknown. |
Daily Pattern (Common Hippo)
- Nocturnal.
- Herd leaves water shortly before dark, following the same branching well-trampled paths for 3-5 km (1.9-3.1 mi)
- Grazing is a solitary activity (except for mothers with calves)
- Usually graze approximately 5 hours except when threatened
- Will also sleep on land at night, on sandy ground inside thickets (Klingel 1995)
- Spends day submerged in deep water with only eyes and nostrils above
surface or basks in sun on sandbars adjacent to water.
- Calves may climb on backs of mothers in water to sun/rest
- If disturbed, entire group submerges, resurfacing after several minutes with only the flat top of the head above water.
- If water dries up or there is a shortage of food, long migrations 40-60 km (24-30 miles) may occur.
- Pygmy Hippos spend day resting near moist or wet places, but also on dry ground
(Lang et al 1990)
- Change sleeping place once or twice a week.
General (Common Hippo)
- Gregarious (but not social; no permanent bonds between adults) and amphibious
- Groups are changeable combinations rather than fixed units
- Basic social unit is mother and her young
- Cows may be followed by up to 4 successive offspring
- Females will also tolerate unrelated young and subadult animals.
- Herd is generally 10-15 but can range from 2-50 (and reach up to 150)
- Average density in lakes: 7 hippos/100 m shoreline
- Average density in rivers: 33 hippos/100 m shoreline
- Pygmy Hippo is less gregarious; usually found solitary or in pairs;
like Common Hippos, also a nocturnal feeder on land
- Little is known about behavior in wild; dens reported at base of erosion-eroded trees on river banks
- Males begin jaw-to-jaw sparring and "yawning" contests at adolescence (7yrs).
- Aggressive behavior is most frequent in dry season when conditions most crowded and breeding most conspicuous
- Territorial bulls may attack and even kill calves
- Mothers counterattack bulls, often successfully because they approach from the side
(don't follow the male's
ritualistic head-on battle procedure)
- Mothers counterattack bulls, often successfully because they approach from the side
(don't follow the male's
- Fighting includes tusk clashing, rearing and pushing with the lower
jaws, slashing and biting
- Bulky shape prohibits agility; contests consist of animals locking teeth and wrestling using
weight
and strength (similar to deer locking antlers)
- Bulky shape prohibits agility; contests consist of animals locking teeth and wrestling using
weight
- Males are territorial only in water, not at night on land
- Both males and females have similar daytime home ranges - about 200 m ( ft) along a shoreline
- Territories defended for mating rights, not food
- Males defend their immediate vicinity
in water
- Size of area and degree of intolerance vary with local conditions (crowding, drought) and perhaps female sexual cycles
- Mature bulls control 50-100 m (55-109 yards) sections of river or 250-500 m (273-547 yards) of lakeshore as exclusive mating territories
- Grazing pastures not part of territory - free access for all
- Dung middens found along hippo paths leading into and out of
territories.
- Constantly renewed at night as the bulls go to pasture and during the day when they emerge and defecate on the heaps
- Middens may reach as high as the hippo's anus
- Ritualized dung-showering occurs between males at the borders of their
territories.
- Two bulls turn sideways, bodies parallel, heads in opposite directions and a distance of several feet between them.
- Tail swings rapidly back and forth while their excrement (mixed with urine) is showered for several feet in all directions.
Displays / Visual signals
- Sight well-developed.
- Mother/calf bond is extremely close.
- Mother licks, nuzzles, scrapes calf with lower incisors
- Discipline achieved by nudging or biting
- Calf responds by prostrating itself; prostration gesture continues into adulthood as sign of submission within herd.
- Threat displays
- Yawning, water-scooping and head-shaking,
- Rearing, lunging, chasing
- Roaring grunting, explosive wheezing.
- Chasing
- Submissive displays
- Facing aggressor with open mouth
- Turning tail
- Urinating with slow tail-wagging,
- Lying prone
- Flight
- Explosive exhalation of breath indicates alarm
- 80% of hippo vocalizations are made underwater, in studies in Tanzania's Ruaha National Park
- Complex bellows, shrieks and grunts are made both in and out of water
- The exhaled bellow of a dominant bull often triggers a deafening chorus from other dominant hippos
- Sound carries at least a mile over the noise of the river
- When a hippo resting at the surface bellows, nostrils flare and sound is hummed through nose and nasopharynx to the air
- Contact call is a deep, choppy "o-o-o-o" often ending in a high "u"
- High-pitched squeals made during threatening frontal confrontations
- Produce at least three categories of sounds underwater
(Barklow 1995, 1997)
- Rarely audible on surface; expel little air when made
- High pitched tonal whines that are somewhat similar to humpback whale song notes
- Pulsed croak between calves and sub-adults
- Click-like sounds (but no evidence yet for echolocation)
- Relatively silent on land; use exhaled breath to express threat and alarm
- Keen sense of smell.
- Likely that individuals recognize each other by scent
- Dung middens do not mark territories on land, as formerly assumed; function of middens not clear to researchers
- Ritualized dung spraying
- By bulls who may deliberately defecate on subordinate animals in their territories
- Subordinate males often spray faeces in the face of dominant males
- Large males may also defecate in water without another male being near
- Syringe-like vomeronasal organ functions underwater drawing a sample of
urine in water through ducts leading from the mouth
(flehmen)
- Almost all male ungulates sample a female's urine to test for possible estrus hormonal levels prior to courtship
- Unique skin (thin epidermis, no sweat glands) loses water at several
times the rate of other mammals.
- Rapid dehydration and overheating are major risks.
- Water or mud is a secondary means of cooling in hot dry weather; sunlight used for warming.
- When agitated can charge at over 30 km/hr.
- Able to climb steep banks if footing is secure.
- Sits on haunches before lying down; rise using front legs first (similar to pigs)
- Their weight aided by very dense bones allows them to travel on the bottom of
lakes/rivers
- Underwater gait similar to a gallop and a trot.
- Do not really swim; move forward when in water by punting off the river bottom
- Other animals that can bottom-walk include nine-banded armadillos and water chevrotain
- Bottom walking may have been also used by ancestors of whales (Thewissen et al. 2007)
- Mature hippos can remain under water for 5 minutes.
- Average submersion is 104 seconds.
- A 2-month calf can remain under water for about 30 seconds.
- Okavango Delta in Botswana owes its topography to hippo's movements along rivers, across land
- Hippos help keep main channels open; also create side channels leading to islands
- Hippo trails serve important role as drainage channels during floods
- On land, hippo gullies may grow to 20 m (65.6 ft) deep that fill with water during rains
- Other species like elephants and buffaloes create land paths; only hippo trails go through lowland waters
- In Okavango Delta, a diverse fish fauna owes its habitat to hippos' habits.
- Most defecation is directly into the water causing a massive buildup of
microorganisms
- Support fish, insects, fish-eating birds and human population that relies on fish for essential protein.
- Egyptian geese, cormorants, cattle egrets (hunt ticks and insects), even turtles, rest on hippo backs and heads.
- Other birds:
- Common Sandpipers forage for aquatic organisms from hippos' backs
- Two species of ox peckers feed on tissue in wounds on hippo skin
- African Pied Wagtails sit on hippos' backs, chase insects above hippos
- African Jacanas observed a national park in Central Northern Republic
(Ruggiero 1996)
- Spend up to 5 hr/day alternately foraging on lake's edge and on hippos' backs
- Take parasites from hippo skin (mutualism)
- Also remove flesh around wounds which seems to retard healing and distress hippos (semi-parasitism)
- 4 species of fish clean hippos in Mzima Springs of Kenya's Tsavo
West National Park (Deeble & Stone 2001)
- Fish feed on vegetable matter/excreta voided into water by hippos
- A carp (Labeo) uses wide rasping mouth to clean hippo's hide
- Garra clean wounds
- Barbus cleans cracks in bottom of feet
- Cichlids clean hippo tail bristles
- Hippos visit sites where fish gather and "invite" cleaning behavior
- Graze in the same areas as buffalo, waterbuck, puku, various antelopes and warthogs
- Enemies: both hyenas and lions take hippo calves; lions occasionally
attack adults
- Hippo usually escapes enemies by entering water
- Hippos and Nile Crocodiles occupy the same water and land habitats; hippos are dominant. (Cott 1975)
(Kofron 1990)
(BBC Wildlife 2009)
- Hippos may push aside a crocodile basking on land or knock it into the water
- A female hippo with a calf or others in the herd will drive out all crocodiles from their pool of water
- Hippos kill crocodiles if they stray too close to calves.
(Eltringham 1999) (Jablonski 2004) (Kingdon 1979) (Laws 1968) (Novak 1991) (O'Connor & Campbell 1986)
- Mostly a grazing lifestyle, but browse may be included in diet; Pygmy Hippos eat more browse
- Pygmy Hippos consume little grass;
main food items are leaves and roots of forest plants, fruits, ferns
- Higher quality diet than that of Common Hippo
- Both Common and Pygmy Hippos are absolutely dependent on vegetation near permanent rivers and streams
- Always graze and forage on land; consume few, if any, aquatic plants
- Spend day in water, night on land grazing 5-6 hours.
- Usually remain close (1-3 km or .6-1.9 mi) to home watercourse during nighttime feeding
- "Hippo lawns" created where grasses kept short by continued grazing
- Grass is grasped with horny lips (up to 20 inches wide in male) and torn off as hippo moves its head from side to side.
- Weakly rooted grasses are eliminated from the grazing areas with this action
- Coarse, tussock-forming grass species not eaten
- Short creeping grass species preferred that can be grasped with lips
- Plant species in diet
include: Cynodon, Panicum, Heteropogon, Sporobolus, Themeda,
Cynodon, Digitaria,
Eriochloa, Tragus, Brachiaria, Urochloa, Chloris, Setaria, Cyperus.
- Unlike many artiodactyls, hippos don't ruminate
- Food is coarsely ground by back molars; front teeth not used in feeding
- Have a multi- chambered stomach where carbohydrates are fermented; two day's worth of grasses can be held at one time
- Intestines extremely long (much longer than other grass eaters)
- Slow rate of digestion derives maximum benefit from a nutrient poor diet of grasses and dry forage
- Low metabolic rate allows survival for many weeks without food
- Eat approximately 1 -1.5 % of body weight
per day
- At least 2.5% of body weight for many other ungulates such as cattle, white rhinos
- Adult hippo consumes 25-40 kg (55-88 lbs) vegetation/day
- Common Hippo carnivory (both scavenging and predation) observed in a drought year in southern Africa. (Dudley 1996)
- Over the last 10 million years hippo diets have been similar to that of modern hippos
(grazing with
some browse)
- Oxygen and carbon isotopes in fossil enamel and bone yield data indicating diet and habitat
(Kingdon 1979) (Klingel 1991) (Nowak 1991) (Smuts & Whyte 1981)
Courtship
- Possession of a territory pre-requisite to mating
- Bulls controlling the most desirable territories have most reproductive success
- Non-territorial bulls (90%) are excluded from reproducing
- Females seasonally polyestrous (lasts 3 days). Males show no evidence of sexual fluctuations
- Mating peaks during dry spells (population most concentrated)
- Mating in water for both species; Pygmy Hippos also mate on land
- Copulation lasts up to one half hour. Female is fully submerged (raises her nose above water periodically)
- Courtship often accompanied by male's wheeze-honking sound
- Comparatively high for such a large animal
- Under good conditions, females can produce a calf each year
- Elephants have a 3-4 year interval
- Rhinos have a 2-3 year interval
Life Stages
 |
A female hippopotamus gives birth to a single
calf; twins are rare. |
- Birth Weight: Common Hippo 25 - 55 kg (55-121 lb); Pygmy Hippos 5.73 kg (12.7 lb)
- Litter Size: one, twins rare
- Female aggressive prior to giving birth
- Leaves herd
- Returns in 10-14 days after calf has imprinted on her
- Imprinting phase also common in other ungulates such as horses and zebras
- Common Hippo birth occurs on land or in shallow water, usually in October or April (during rains)
- Pygmy Hippos born on land throughout year
- Birth occurs hind legs first
- Common Hippo calf may have to push off from bottom and come to surface for its first breath
- Adaptations for underwater nursing: ears automatically fold and nostrils close (even when nursing on land).
- Frequently surface to breathe
- Calves remain in water when mother leaves to forage, returning periodically to allow it to suckle
- Infants can remain underwater only about 2 minutes
- Normally breathe about every 30 seconds
- Indirect evidence that during poor environmental conditions, nursing period is extended and calves suckle more than one cow
- Lactation lasts approximately 1 year
- Grazing begins at 1 month; substantial grazing at 5 months
- Weaned at 6-8 months for both species
- In wild, occasional infanticide by adult or juvenile males
- Until about one year, calves vulnerable to Nile Crocodile attacks
- Young remain with mother for several years
- Sexual maturity
in captivity much younger than reported for wild
- In captivity: 3-4 years
- In the wild: males 6-13 yrs.; females 7-15yrs.
- It is unlikely that young bulls are allowed to breed effectively until much older
- Fertility doesn't' decrease much with declining age
- Many females still can reproduce in 30s and 40s
- Psychological maturity in the wild is probably about 20 years
Captive Breeding
- Does well in captivity and breeds easily but far below breeding rate in the wild.
- Breeding groups are small (rarely more than 3) because of the space limitations in zoos.
(Hlavacek et al. 2005) (ISIS Web Site) (Klingel, 1990) (Thompson 2002)
- First exhibited in the London zoo in 1850
- Paris zoo exhibited in 1853
- Common in many large zoos:
- Easy to keep and breed.
- Resistant to disease
- ISIS captive population
- As of 2004, 290 captive-born Pygmy Hippos in 135 zoos. (Hlavacek et al. 2005)
- Solitary Pygmy Hippos in captivity may experience undue stress when pairs of females or male/female pairs housed together.
(Lewison & Oliver 2008a,b ) (Nowak 1991) (Oliver 1993) (Kingdon,1979)
- IUCN Status: Pygmy Hippo (Lewison & Oliver 2008a)
- Presently (2008) the population trend is decreasing; with no regional conservation plans, "viability should be considered extremely poor."
- 2006 Endangered
- 1996 Vulnerable
- 1994 Vulnerable
- 1988 Vulnerable
- 1986 Vulnerable
- IUCN Status: Common Hippo (Lewison & Oliver 2008b)
- 2006 Vulnerable A4cd Ver. 3.1
- 1996 Lower Risk/least concern
- CITES Status: Pygmy Hippo Appendix I (no trade allowed)
- CITES Status: Common or River Hippo Appendix II (trade must be regulated)
- 1968-present Protected by 1968 African Convention on the Conservation of Nature and Natural Resources, but protection not enforced.
- 1990-2010: a 7-20% reduction in Common Hippo populations
- 2010-2040 a 30% reduction predicted in populations if current trends continue
- 125,000 to 148,000 Common Hippos estimated across their range
(Lewison & Oliver 2008)
- Most numerous in: Ethiopia, Kenya, South Africa, Sudan, Tanzania, Uganda, Zambia and Zimbabwe. Largest populations found in Zambia.
- Largest declines in Democratic Republic of Congo
- In East Africa' Democratic Republic of Congo 30,000
- Tens of thousands in Ethiopia, Sudan and Tanzania
- Several thousand in Kenya and Uganda
- In all of East Africa, perhaps 70,000
- About 7,000 in West Africa, in numerous small groups; fragmented populations at risk
- 2,000-3,000 Pygmy Hippos remaining in Sierra Leone, Republic of Guinea, Ivory Coast, Liberia
( IUCN Action Plan estimate, Oliver 1993))
- This estimate may have been too high
- Population estimate only available in 1993 for Sierra Leone: 80-100 individuals
- Two key areas for Pygmy Hippo habitat and conservation:
- Sapo National Park in eastern Liberia - 1318 sq km (509 sq mi)
- Tai National Park in western Ivory Coast (Côte d'Ivoire)
- Common Hippo:
- Not in any danger of extinction but potentially vulnerable because of specialized ecology
- Loss of grazing habitat
- Desertification of some parts of Africa
- Many groups in west Africa have less than 50 animals
- Pygmy Hippo:
- Farming and human settlement
- Logging which leads not only to habitat destruction but is often tied to poaching when forests become more accessible
- Wars in Sierra Leone, Guinea and Liberia
- Limited enforcement of existing protections in Sierra Leone, Guinea, Ivory Coast
- Oil pollution in estuaries by the sea further threaten Pygmy Hippo populations. (Oliver 1993)
- Conservation status and viability of this species considered poor. (Lewison & Oliver 2008 in IUCN assessment)
- Major threat: Humans
- Increasing human population, timber and fish industries
- Killed because of destructiveness to crops and attacks on fishermen
- Hunted for fish bait in some areas
- Hunted for meat in some areas.
- Hams are palatable but carcasses spoil quickly in hot weather
- Meat is avoided in some areas (Zambians believe it causes leprosy)
- Muslim communities consider it too closely related to the pig
- Main trophy product is tusks (softer and easier to carve than the true ivory of elephant tusks)
- Thick hide is cut into strips and rubbed with fat to form a whip known in South Africa as the "sjambok"
WEB RESOURCES
- IUCN/SSC Hippo Specialist Group: Website designed to promote conservation and research for hippos and their habitat. Includes free downloadable information packets and hippo maps for grade school youth and conservation groups; see also an extensive bibliography for hippos.
- EDGE: Evolutionarily Distinct & Globally Endangered: Website maintained by the Zoological Society of London for little-known animals or ones currently receiving little conservation attention. Focus is on species that "represent a sinificant amount of unique evolutionary history" Pygmy Hippos are listed. Site also has a geographical search feature that pinpoints where individual species can be found.
- Video of 2011 hippo birth at San Diego Zoo. Link from San Diego Zoo's website.
© 2001 San Diego Zoo Global. Last updated February 2011. Disclaimer: Although San Diego Zoo Global makes every attempt to provide accurate information, some of the facts provided may become outdated or replaced by new research findings. Questions and comments may be addressed to library@sandiegozoo.org.
Return to the Fact Sheets page
