Water Chevrotain
(Hyemoschus aquaticus)
Chevrotains are among the smallest ruminants (an animal with an extensive gut that is able to enable digestion of its high-fibre diet though fermentation) and are often known as ‘mouse pigs’. They are thought of as an intermediate form between pigs and deer, although they are closer to a rabbit in size. The male’s two upper canine teeth grow continually and protrude from the mouth, inspiring the name ‘Fanged deer’. The status of the water chevrotain is not well known across its entire range. There is some evidence that it is declining in specific areas.
Urgent Conservation Actions
Status surveys to ascertain popluation size and distribution.
West and Central Africa: From Liberia in the northwest round the coast as far south as Angola, extending as far east as Uganda.
Evolutionary Distinctiveness
Order: Artiodactyla
Family: Tragulidae
During the Miocene and Oligocene chevrotains had a global distribution, but today the four species are restricted to the jungles of Africa and south East Asia. Chevrotains have remained virtually unchanged in their form throughout 30 million years of evolution. They are considered to be primitive ruminants and represent a living link between ruminants and non-ruminants. The water chevrotain is the only species in its genus and the most primitive of all the four species of chevrotain.
Head and body length: 70-80 cm Shoulder height: 23-40 cm Tail length: 10-14 cm
Weight: 8-13 kg
Chevrotains are among the smallest ruminants and are often known as ‘mouse pigs’. The water chevrotain has a head and body length of 70-80cm and the shoulder height is 23-40cm. Tail length is 10-14cm and weight is between 8 and 13kg, with females generally weighing 20% more than males. The bulky body is supported by short thin legs. The coat is blackish red in colour with lighter spots positioned in rows and forming continuous strips. The throat and chest are highly stripped. Chevrotains are ruminants, which basically means that their gut is modified to ferment highly fibrous food. There are four gut chambers, although the third is not well developed. Their teeth also resemble those of ruminants. However, chevrotains also exhibit many non-ruminant characteristics including a lack of horns or antlers. The males possess projecting continually growing upper canines that are peg like in females.
Water chevrotains are nocturnal (or night-active), spending the day hidden in dense tropical forests. Their diet consists mainly of fallen fruit and foliage. Like other forest ruminants, water chevrotains are solitary. They also share some behavioural characteristics with pigs, such as simple sexual behaviour lacking in visual display and limited to communication through scents and cries. The cry of the male stops the female's movements and is followed by a lengthy copulation. Chevrotains have a habit of lying down rump first which is also similar to the behaviour of pigs. Home range has been estimated at 23-28 hectares in males and 13-14 hectares in females. Home ranges always border water at some location. The home ranges of adults of the same sex do not overlap but male home ranges overlap those of several females. There is no evidence of territorial defence. In Gabon, population density was estimated at approximately 7.7-28 per km2. Chevrotain reproduction is not well understood. In the water chevrotain breeding occurs throughout year with a single young being born in a litter. Soon after birth the mother hides the youngster in vegetation and only retrieves it for feeding. Gestation is 6-9 months, lactation is 3 months and sexual maturity occurs at 10 months. Males possess anal and preputial glands which are used in scent marking – they mark their home range with urine and faeces laced with scent from the anal gland. The heaviest and oldest animals are dominant, but no established hierarchy exists due to the solitary nature of the animals. Fighting between males is limited to short rushes and biting with the sharp canines. The small size of chevrotains makes them easy prey for predators including large snakes, crocodiles, eagles and forest-dwelling cats. Longevity is an estimated 10-14 years.
Water chevrotains are mainly terrestrial and reside in tropical forests. They retreat into water if they sense danger.
West and central African rainforest; Angola, Benin (possibly), Burkina Faso (possibly), Burundi, Cameroon, Central African Republic, Congo, The Democratic Republic of the Congo, Côte d'Ivoire, Equatorial Guinea, Gabon, Ghana, Guinea, Guinea-Bissau (possibly), Liberia, Nigeria, Rwanda, Senegal (possibly), Sierra Leone, Togo (possibly), Uganda.
Population Estimate
The estimated total population of the water chevrotain in 1999 was 278,000, although there are currently no more recent figures.
Population Trend
There is some evidence that the water chevrotain is declining in specific areas, but first-hand information is scarce. There is also no information on past distribution.
The water chevrotain is considered ‘Data Deficient’ in the 2004 IUCN Red List of Threatened Species. The status of the water chevrotain is not well known on a national basis across its extensive range. There is some evidence that it is declining in specific areas, but first-hand information is scarce. There is also no information on past distribution. In 1996 this species was considered Lower Risk/near threatened.
In western Central Africa threats to the forest include unsustainable and illegal logging operations, no incentives for sustainable use, poor environmental governance, an insufficiently developed policy framework, political instability and conflict, population growth and a weak protected area network. Also there is sometimes inadequate capacity building for environmental management across this species’ distribution and an under-developed general understanding of scientific environmental issues. As a result of factors such as these 85% of Africa's tropical rainforest has now been destroyed. The IUCN considers habitat loss and degradation through agriculture and infrastructure development to be threats address this species. The water chevrotain is also hunted for food.
Conservation Underway
A number of protected areas exist throughout this species range, although they are not always effective in preventing illegal habitat exploitation. In many areas there is a desperate need for funding and qualified park staff as well as effective law enforcement.
Conservation Proposed
The IUCN has highlighted the need for research into the population numbers and range of the water chevrotain. Site-based maintenance and conservation are also required to protect this species.
Baillie, J. and Groombridge, B. (compilers and editors) (1996). 1996 IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland.

Deer Specialist Group (2000). Hyemoschus aquaticus. In: IUCN (2004). 2004 IUCN Red List of Threatened Species. Downloaded on 15 March 2006.

Dubost, G. 1984. Comparison of the diets of frugivorous forest ruminants of Gabon. Journal of Mammalogy, 65(2): 298-316

Doubost G. 1978. Un apercu sur l'ecologie du chevrotain africain Hyemoschus aquaticus Ogilby, Artiodactyle Tragulide. Mammalia 42 (1): 1-62

East, R. (compiler) 1999. African Antelope Database 1998. IUCN/SSC Antelope Specialist Group.

Grubb, P. 1993. Order Artiodactyla. Pp. 382 in D. Wilson, D. Reeder, eds. Mammal Species of the World (2nd ed). Washington: Smithsonian Institution Press.

Hilton-Taylor, C. (compiler). 2000. 2000 IUCN Red List of Threatened Species. IUCN, Gland, Switzerland and Cambridge, UK.

Kingdon, J. 1979. East African Mammals, Vol III, Part B. N.Y.: Academic Press, Inc.

Macdonald, D. (ed.) 2001. The New Encyclopedia of Mammals. Oxford University Press, Oxford, New York.

Nowak, R.M. (ed.) 1999. Walkers Mammals of the World. Sixth edition. The Johns Hopkins University Press, Baltimore and London.

Robin, K. 1990. Chevrotains. Pp. 118-123 in B. Grzimek, ed. Grzimek's Encyclopedia of Mammals, Vol. 5. N.J.: McGraw-Hill Publishing Company.

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