 Hyemoschus
aquaticus
Water chevrotain |
Taxonomy | Description
| Reproduction | Ecology
| Behavior | Distribution
| Conservation | Remarks
| Literature |
| Taxonomy
-
Hyemoschus aquaticus [Ogilby, 1841].
-
Citation: Proc. Zool. Soc. Lond., 1840:35 [1841].
-
Type locality: Sierra Leone, Bulham Creek.
The taxonomic record (above) is taken from Wilson and Reeder (1993).
Originally named Moschus aquaticus - thereby allying it with
musk deer - the water chevrotain is thought to be the most ancestral of the
extant tragulids (Robin, 1990; Wilson and Reeder, 1993). Three subspecies
have been named, although the validity of these names is questionable
(Kingdon, 1997). Synonyms for H. aquaticus are batesi
and cottoni (Wilson and Reeder, 1993)
General Characteristics
Unusual for ungulates, female water chevrotains are larger than males, weighing
(on average) over two kilograms more than the 10 kg males (Kingdon, 1997).
Body length is approximately 85 cm, and shoulder height is roughly
35 cm (Robin, 1990).
Reported measurements for water chevrotain (Hyemoschus
aquaticus) |
| Source |
Adult Weight |
Head & Body Length |
Shoulder Height
|
Tail Length |
| Alden et al., 1995 |
8-13 kg |
70-80 cm |
32-40 cm |
10-14 cm |
| Dubost, 1984 |
10.8 kg |
- |
- |
- |
| Happold, 1973 |
14-16 kg |
91-102 cm |
36 cm |
- |
| Kingdon, 1997 |
7-16 kg
9.7 kg
 (average)
12 kg
 (average) |
60-102 cm |
30-40 cm |
7.5-15 cm |
| Nowak, 1991 |
7-15 kg |
60-85 cm |
30.5-55 cm |
7.5-15 cm |
| Robin, 1990 |
10-15 kg |
75-85 cm |
35-40 cm |
10-15 cm |
The sleek coat is an overall rich reddish brown colour above and white
on the undersides (Happold, 1973; Nowak, 1991; Kingdon, 1997). The
body is marked with a striking pattern of horizontal white stripes running
from the shoulder to the rump, with white spots on the back arranged in vertical
rows (Nowak, 1991; Kingdon, 1997). The chin, throat, and chest are
covered in coarse hair, and patterned with bold white inverted
"v"s (Kingdon, 1997).
The hind quarters of Hyemoschus aquaticus are powerfully muscled,
and much higher than the shoulders, giving the body a distinctly sloped
appearance (Happold, 1973; Robin, 1990; Kingdon, 1997). When walking,
the head is held towards the ground, creating a profile which is a nearly
perfect cone, allowing the water chevrotain to penetrate virtually impassable
thickets (Dubost, 1979). The efficiency of this tunnelling profile
is enhanced by a shield of thick, reinforced skin on the dorsal surface,
which protects the back from injuries inflicted by dense, resistant vegetation
(Dubost, 1979). This thick skin extends to the rump and throat, which
also have deep muscles which may reduce the incidence of severe injuries
inflicted by the tusks (Kingdon, 1997). The legs are short, and rather
delicate for the bulk of the body, while the hooves resemble those of swine,
with the dewclaws being held off the ground (Happold, 1973; Kingdon, 1997).
There is a patch of shiny black skin behind the hocks (Kingdon, 1997).
The tail is short, with a fluffy white underside (Nowak, 1991;
Kingdon, 1997).
The neck is short and thick (Kingdon, 1997). The small head is narrow
and pointed, ending in a pointed, leathery nose with slit-like nostrils (Nowak,
1991; Kingdon, 1997). The ears are small and round (Kingdon, 1997).
Neither sex has horns or antlers as defences (Robin, 1990). However,
like the musk deer and Chinese water deer, the upper canine teeth tusks well
developed and sabre-like in males, protruding out of the mouth on either
side of the lower jaw (Happold, 1973; Kingdon, 1997). Females also
have enlarged canines, but they are shorter and blunter than in
males (Kingdon, 1997). Male chevrotains possess unique glands
under the chin in the angle of the lower jaw (Robin, 1990; Kingdon, 1997).
Ontogeny and Reproduction
Due to the secretive nature of this species, little is known about its life
cycle - and reports often vary dramatically. Females give birth to
one offspring at a time, typically once every year (Dubost, 1978 in
Nowak, 1991; Robin, 1990; Kingdon, 1997). However, the presence of
four mammae in females indicate the potential for a larger litter size (Kingdon,
1979 in Nowak, 1991). Reported gestation lengths range from
a low of four months (Kingdon, 1997) to a high of up to 9 months (Dubost,
1978 in Nowak, 1991) - more than a two-fold difference. Dubost
and Feer (1992) reported the gestation period to be 219 days, a more specific
number than the 6-9 month range provided by Dubost (1978 in Nowak,
1991).
In Gabon, births occur throughout the year, although there is a peak in births
during the first few months of the twice-annual dry seasons - in January
and July-August (Dubost and Feer, 1992). These birthing peaks
correspond to peaks in the quantity and quality (protein content) of fruits
which this species feeds upon (Dubost and Feer, 1992). Infants are
usually found separate from their mothers, "lying up" for the first three
months of life (Dubost, 1978 in Nowak, 1991; Kingdon, 1997). During
this initial hiding period, the mother will visit her offspring periodically
to suckle, at which time small infants are also washed using the tongue (Robin,
1990; Kingdon, 1997)
Young animals are usually very sedentary, and rarely play since they never
come in contact with others of the same age (Robin, 1990). Suckling
lasts for 3-6, or even up to 9 months (Dubost, 1978 in Nowak, 1991;
Kingdon, 1997). Individuals reach sexual maturity at 9-26 months of
age, at which time young animals disperse from their mother's home range
(Dubost, 1978 in Nowak, 1991). Growth continues until about
2 years of age, when full adult dentition is obtained (Kingdon, 1997).
Water chevrotains typically do not survive past 8 years of age, but
have a potential lifespan of 11-13 years (Robin, 1990; Kingdon, 1997).
Ecology
The water chevrotain inhabits river valleys and lowland rainforests, and
is rarely found more than 250 meters from a source of fresh water (such as
a river, marsh, or lake) (Dubost, 1978 in Nowak, 1991; Kingdon, 1997).
It is exclusively nocturnal, being active between the hours of 1800
and 0600 (Dubost, 1978 in Nowak, 1991; Robin, 1990). Foraging
in in clearings, floodplains, and along river banks at night, H.
aquaticus retires to a hiding spot in dense cover during the day (Kingdon,
1997). Resting postures include lying down and "sitting" on the hind
legs with front legs propping the body up (Robin, 1990)
As with many small forest ungulates, the water chevrotain is strictly solitary
(Robin, 1990; Kingdon, 1997). Adult female occupy home ranges averaging
13-14 hectares in size, and are typically accompanied by their latest offspring
(Dubost, 1978 in Nowak, 1991). There is little overlap between
the home ranges of neighbouring animals, and even when there is cohabitation
there is typically very little interaction (Kingdon, 1997). Females
usually settle down and remain in the same home range for life after they
reach maturity (Dubost, 1978 in Nowak, 1991; Robin, 1990). Males,
on the other hand, are much less sedentary, usually occupying a given area
for less than a year before moving on (Dubost, 1978 in Nowak,
1991). The home ranges of males are typically much larger than those
of females, averaging 20-30 hectares in size and overlapping with the home
ranges of at least two females (Dubost, 1978 in Nowak, 1991; Kingdon,
1997). There is no evidence of territoriality within home ranges, but
nevertheless water chevrotains are well-spaced (Dubost, 1978 in Nowak,
1991). Recorded population densities vary between 7.7 to 28.0 animals
per square kilometer (Dubost, 1978 in Nowak, 1991).
Water chevrotains are hunted by most carnivores which share the same habitat,
with young animals also being taken by both nocturnal and diurnal birds of
prey (Robin, 1990). When in the vicinity of a predator, "freezing"
is the typical response of the water chevrotain, in the hopes of going undetected
(Kingdon, 1997). If seen and pursued, this species retreats to water
(Kingdon, 1997). As its name suggests, H. aquaticus is quite
comfortable in the water, and can dive and swim beneath the surface, although
only for short periods before tiring (Kingdon, 1997). May hide almost
completely submerged (Happold, 1973).
H. aquaticus forages primarily in mature forest, along edges, and
in secondary forest, with much less feeding activity in waterside and flooded
habitats (Dubost, 1984). Scent is the primary sense used when searching
for food (Kingdon, 1997). The water chevrotain is primarily a frugivore
- stomach content analysis of 19 animals in Gabon revealed that fruits comprise
68.7% of all foods eaten (by dry weight - Gautier-Hion et al., 1980;
Dubost, 1984). The rest of the diet includes leaves (9.9% ), petioles
and stems (20.5% ), animal matter (0.14%), flowers (0.70% ), and fungi (0.13%
), with no tree gums being consumed (Gautier-Hion et al., 1980; Dubost,
1984). Compared to duikers - other small frugivores which share the
same habitat - H. aquaticus eats relatively little fruit and fungi
(the diet of duikers may contain upwards of 80% fruit), but many more succulent
stems (Dubost, 1984).
76 species of fruits have been identified in the diet of H. aquaticus,
and many more are eaten (Dubost, 1984). Dubost (1984) found several
species to be preferred - namely Cylindropsis parvifolia (Apocynaceae),
Bombax buonopozense (Bombacaceae), Alchornea cordifolia
(Euphorbiaceae), Coelocaryon preussi or Pycnanthus angolensis
(Myristicaceae), and Cissus dinklagei (Vitaceae). Kingdon (1997)
suggested that figs (Ficus), Pseudospondias fruits, palm nuts
(Elaeis), and breadfruit (Treculia) are consumed, as well as
the fruits of gingers and arrowroots. Most fruits consumed by H.
aquaticus is a diameter between 0.5 and 2.0 cm (Dubost, 1984).
Most of the animal matter eaten by the water chevrotain is insects - this
species actively hunts for ants by licking the ground along ant trails (Dubost,
1984). However, crabs, carrion, and scavenged fish have also been noted
(Kingdon, 1997). The water chevrotain consumes significantly less animal
matter and fungus during the dry season, as well as 44% fewer fruit
species (Dubost, 1984). Young individuals which are still nursing
eat smaller amounts of fruit than adults (only 48.4% of the diet) and a larger
proportion of leaves (31.3%) (Dubost, 1984). In these unweaned animals,
stems comprise 19.1% of stomach contents, while flowers make up only 0.80%
(Dubost, 1984).
Behavior
Due to their solitary nature, interactions between water chevrotains are
restricted to agonistic and reproductive encounters. Males fight more
frequently than females, principally over territory (Robin, 1990; Kingdon,
1997). Fights are typically short in duration, and involve the two
competing males rushing at each other with mouths open, poking at each
other with their muzzles and biting, using the canines in the upper jaw and
incisors in the lower jaw (Robin, 1990; Kingdon, 1997). These fights
may be responsible for the fact that mature males live up to several kilometers
apart (Kingdon, 1997).
The water chevrotain has several vocalizations, including a scream when wounded,
and an alarm bark (Kingdon, 1997). When fighting, females produce a
high pulsing chatter (Kingdon, 1997). As with pigs, male chevrotains
vocalize when following an estrous female, typically through a closed mouth
(Kingdon, 1997). While being followed, a receptive female will stop
at each cry, allowing the male to lick her rump. After several repetitions
of this, the male mounts (Kingdon, 1997).
Distribution
The west and central rainforest block from Sierra Leone to Uganda.
Countries: Angola, Benin?, Burkina Faso?, Burundi, Cameroon, Central
African Republic, Congo, The Democratic Republic of the Congo, Côte
d'Ivoire, Equatorial Guinea, Gabon, Ghana, Guinea, Guinea-Bissau?, Liberia,
Nigeria, Rwanda, Senegal?, Sierra Leone, Togo?, Uganda (IUCN, 2003).
Range Map (Adapted from Kingdon, 1997)
Conservation Status
The estimated total population of the water chevrotain is 278,000 (East,
1999). The IUCN (2003) has not assigned a category to the water chevrotain,
listing it as data deficient. Due to its secretive nature, there is
little information on its status in individual countries within its extensive
range, although there is some evidence that it is declining in specific areas
(IUCN, 2003). Major threats to the survival of this species include
loss of habitat to agriculture and expanding human development, as well as
hunting for food by humans (IUCN, 2003). The population of H.
aquaticus in Ghana is listed on CITES Appendix III (CITES, 2003).
Remarks
The genus name Hyemoschus is derived from the Greek Hus, a
hog, and Moschus, the genus of the musk deer (derived from the Greek
word for musk). This species was originally classified as small musk
deer due in part to the long canines of the males, but its stature and habits
are reminiscent of pigs. Aquaticus (Latin) living in or near
water - this species is rarely found far from water, which it dives into
to escape from predators. Chevrotain is a diminutive form of the French
chèvre, a goat.
-
-
Local names (from Happold, 1973)
-
Giminan [Dyula]
-
Diaure ndiyam [Fula/Fulani]
-
Isè [Yoruba]
-
-
French
-
Chevrotain aquatique, chevrotain africain (Robin, 1990)
-
-
German
-
Afrikanisches Hirschferkel (Robin, 1990), Zwergmoschustier
(Happold, 1973).
-
-
Spanish
-
Antilope amizclero o enano de agua (IUCN, 2000)
|
Literature
Cited
Alden, P. C., R. D. Estes, D. Schlitter, and B. McBride. 1995.
National Audubon Society Field Guide to African Wildlife. New
York: Chanticleer Press.
CITES (Convention on the International Trade in Endangered Species of Wild
Flora and Fauna). 2003. Appendices I, II and III, as adopted
by the Conference of the Parties, valid from 16 October 2003. Available
online at http://www.cites.org/
Dubost, G. 1979. The size of African forest artiodactyls as
determined by the vegetation structure. African Journal of Ecology;
17(1): 1-17.
Dubost, G. 1984. Comparison of the diets of frugivorous forest
mammals of Gabon. Journal of Mammalogy; 65(2): 298-316.
Dubost G., and F. Feer. 1992. Saisons de reproduction des petits
Ruminants dans le nord-est du Ghabon, en fonction des variations des ressources
alimentaires. Mammalia; 56(1): 25-43.
East, R. [compiler]. 1999. African Antelope Database 1998. IUCN/SSC Antelope
Specialist Group. Gland, Switzerland and Cambridge, UK: IUCN.
Gautier-Hion, A., L. H. Emmons, and G.Dubost. 1980. A
comparison of the diets of three major groups of primary consumers of Gabon
(primates, squirrels and ruminants). Oecologia (Berlin); 45: 182-189.
Happold, D. C. D. 1973. Large Mammals of West Africa. London:
Longman Group, Ltd.
IUCN (International Union for Conservation of Nature and Natural Resources).
2003. 2003 IUCN Red List of Threatened Species. Available
online at http://www.redlist.org/
Kingdon, J. 1997. The Kingdon Field Guide to African Mammals. Academic Press,
London and New York: NaturalWorld.
Nowak, R. M. [editor]. 1991. Walker's Mammals of the World (Fifth Edition).
Baltimore: The Johns Hopkins University Press.
Robin, K. 1990. Chevrotains. In Grzimek's Encyclopedia
of Mammals. Edited by S. P. Parker. New York: McGraw-Hill. Volume
5, pp. 120-123.
Wilson, D. E., and D. M. Reeder [editors]. 1993. Mammal Species of the World
(Second Edition). Washington: Smithsonian Institution Press.
Available online at
http://nmnhwww.si.edu/msw/
Additional Resources
Dubost, G. 1975. Le comportement du Chevrotain africain,
Hyemoschus aquaticus Ogilby (Artiodactyla, Ruminantia). Sa
signification écologique et phylogénétique.
Zeitschrift fur Tierpsychologie; 37: 403-501.
Dubost, G. 1978. Un aperçu sur l'écologie du chevrotain
africain Hyemoschus aquaticus Ogilby, Artiodactyle Tragulide.
Mammalia; 42: 1-62.
Dubost, G., and R. Terrade. 1970. La transformation de la peau
des Tragulidae en bouclier protecteur. Mammalia; 34: 505-513.
Happold, D. C. D. 1987. The Mammals of Nigeria. Oxford: Clarendon Press.
pp. 209-210
IEA (Institute of Applied Ecology) 1998. Hyemoschus aquaticus.
In African Mammals Databank - A Databank for the Conservation
and Management of the African Mammals Vol 1 and 2. Bruxelles: European
Commission Directorate. Available online at
http://www.gisbau.uniroma1.it/amd/amd017b.html
|
|
