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OCR for page 291
26
Mouse Deer
Mouse deer (Tragulus spp. and Hyemoschus aqua-
ticus) are among the smallest ruminants known. The
lesser mouse deer of Southeast Asia is probably the
smallest; an adult stands only 20 cm high and weighs
a mere 1-2.5 kg.
Although they look vaguely like tiny deer, mouse
deer differ in several particulars. The stomach is simpler and (like the
camel's) has three instead of four effective compartments. Rumination
occurs, but mouse deer are the most primitive of all ruminants. Indeed,
they share a number of characteristics with nonruminants, including
lack of horns or antlers; continually growing, tusklike upper canines
in males; sharp-crowned premolars; and four fully developed toes.
Virtually unchanged in 25 million years of evolution, these are
solitary, nocturnal, retiring animals that have seldom received detailed
research. Whether they might make suitable microlivestock is un-
known. However, they seem to be tractable, and people in Southeast
Asia (Sarawak, for instance) have traditionally kept at least one of the
species as backyard pets. Moreover, mouse deer are indigenous to
tropical lowland regions and withstand the heat and humidity that are
stressful to most conventional livestock species. They probably also
are resistant to many diseases of those torrid regions.
In the United States, mouse deer are being raised as laboratory
animals for basic research on ungulates. This is because the animals
are easier to handle than large deer or goats.2
11
APPEARANCE AND SIZE
Mouse deer are graceful, lithe, and look somewhat like large rodents.
' Also known as chevrotains. These animals are not true deer; their common name is a
misnomer. Although they resemble deer, they also have some features of pigs. Zoologists
classify them as a separate family, the Tragulidae. There are three Asian species: the
lesser Malayan mouse deer Tragulus javanicus, the Indian mouse deer T. meminna,
and the larger Malayan mouse deer T. napu. There is one African species, the water
chevrotain Hyemoschus aquaticus.
2 Information from I. Muul.
291
OCR for page 292
~,-
292
MICROLIVESTOCK
The Asian species are the shape and size of an agouti (see page 1981;
the African species is more like the pace (see page 262~. All have short
legs, a small head, and a pointed snout. Adults weigh from 1 to 5 kg,
depending on species. The head and body are only 0.~1 m long, and
the shoulder height is merely 2~36 cm. Males are generally smaller
than females.
In most species the body is a rich brown with white spots and
stripes. The belly is usually white. The animals stand on the middle
toes, so that the lateral ones do not touch the ground. Neither sex
bears antlers. In males the upper canines form long tusks that may
extend outside the lips and even to below the line of the jaw.
DISTRIBUTION
Twenty-five million years ago, early forms of mouse deer existed
throughout Asia, Africa, and Europe. Today's species are restricted
to tropical forests and mangrove thickets of Southeast Asia and Central
Africa.
Of the three Asian species, the Indian mouse deer occurs in southern
India and Sri Lanka; the larger Malayan mouse deer occurs on the
mainland of Southeast Asia and the lesser Malayan mouse deer occurs
on Java as well. The water chevrotain, a related African animal, is
found from eastern Zaire to the Atlantic coast.
~ Hi. ~ ~
'~
Range of Asian mouse deer: (1) Indian mouse deer; (2) larger and lesser Malayan mouse
deer.
OCR for page 293
MOUSE DEER
(
Range of water chevrotain.
STATUS
293
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In recent years, human encroachment into the forest has caused the
destruction of the mouse deer habitats and has put various mouse deer
species under a pressure that is causing their populations to decline.
HABITAT AND ENVIRONMENT
These animals inhabit equatorial forests and mixed secondary tropical
forest. They generally live among undergrowth on the edges of dense
lowland rainforests. They especially haunt rivers and swampy bush
areas, seeking escape by water when in danger.
BIOLOGY
Little about these animals is recorded. Essentially vegetarians, they
feed chiefly on fruits, supplemented by leaves. They also eat insects
(for instance, ants), if available. They do not seem to eat grassy
The premolars of the mouse deer are designed for piercing and
chopping food rather than for chewing. As noted, the stomach consists
of three functional compartments: the rumen, the reticulum, and the
abomasum. (The omasum of ruminants is represented only by a
rudimentary area.) The stomach occupies almost the whole of the
3 Information from G. Dubost.
OCR for page 294
294
MICROLIVESTOCK
abdominal cavity, extending from the diaphragm to the pelvic inlet,
which provides this small animal with large food-storage capacity.
The blood has a very high erythrocyte (red blood corpuscle) count
as well as the smallest erythrocyte size of any mammal. The flesh is
''white" and the muscles contain little myoglobin.
Mature females reproduce almost continuously, and usually regard-
less of season. In the female larger Malayan mouse deer, mating occurs
within 2 days of giving birth. In the African species, many births are
synchronized with the rainy seasons, when fruits are plentiful. The
gestation period is about 5~ months, depending on the species. There
is only one young per birth. Weaning normally occurs at 2-3 months,
but can occur as early as 3 weeks, with sexual maturity achieved at
=5 months (Asian species) and 10 months (African species). The
young stay alone, hidden in vegetation during the first month or two.
BEHAVIOR
Mouse deer are shy, keeping to dense jungle and depending on
concealment for protection. Although often present in large numbers,
they are seldom seen. Preferring to be near lakes, rivers, or streams,
they can nevertheless wander 1 km or more from water. They feed
mostly at dusk or at night, sheltering in undisturbed areas or under
shady bushes during the day. They utter weak, bleating sounds, and
when frightened, jump a meter or more in the air.
Communication is by scent and calls. The African species possess
anal and preputial glands, with which, along with urine and feces, they
mark their home ranges. Males of both Asian and African species
possess a chin gland to mark either the vegetation or their mates.
Mouse deer are among the most excitable, nervous, and jumpy
animals. One must tread softly in their presence for fear of causing
absolute pandemonium and mishap.
USES
Mouse deer are widely sought by native people for food, and their
meat is highly regarded. Dressed carcasses have a high proportion of
muscle (84 percent in Asian species), low proportion of bone (15
4 Information from G. Dubost.
Opposite: Water chevrotain. (A.R. Devez, CNRS, Mission Biologique au Gabon)
OCR for page 295
OCR for page 296
296
MICROLIVESTOCK
percent), and an insignificant amount of fat. The ratio of muscle to
bone is large 5.6:1. The mean dressing percentage of 62.1 percent is
greater than that reported for cattle, water buffalo, or goat.5
HUSBANDRY
Adults are wild, generally intractable, and "flighty," but young
animals (at least of the Asian species) tame readily and make good
pets. Nevertheless, these are delicate creatures and must always be
handled gently. Individuals caught in the wild tend to bash against the
sides of cages.
Despite an unpromising temperament, Asian mouse deer are regularly
bred in zoos, including those in Amsterdam, New York, and Zurich.
They also have been reared successfully in small enclosures at several
research institutes, such as the I.R.E.T Institute, Makokou, Gabon;
the Institute of Medical Research in Kuala Lumpur, Malaysia; and at
Fort Detrick in the United States.
Perhaps the best way to breed this animal is by using the battery
system of small units comprising one male and two females per cage.
The costs are mostly for obtaining suitable enclosures and for feeding
and watering troughs.6 The cages must be covered with mesh because
the mouse deer can jump. However, the covering must be sufficiently
high to allow the male to stand with its body vertical during copulation.7
They can be fed a variety of foods and grow well on stems of bean
plants.
ADVANTAGES
As noted, these are small, seemingly tractable creatures that are at
home in the heat, humidity, and diseases of tropical lowlands. They
might play a particularly important role as livestock for tropical
rainforests; the forests could be left standing while the animal still
produces meat. Today, in a widely condemned process, tropical
rainforests are being felled in order to raise cattle for meat.
5 Information from M.K. Vidyadran.
6 Information from Roy A. Sirimanne.
7 Information from I. Muul.
OCR for page 297
MOUSE DEER
LIMITATIONS
297
Small size makes mouse deer easy prey for various predators. In
the wild, snakes, crocodiles, eagles, and forest cats feed on them.
Mouse deer are among the most excitable, nervous, and jumpy
animals. One must tread softly in their presence for fear of causing
absolute pandemonium and mishap.
The different species are solitary, and it is difficult to keep many
individuals (especially males) in a restricted space. They must be kept
in a quiet enclosure, with cover or good shelters.
RESEARCH AND CONSERVATION NEEDS
The survival of these four "living fossils" depends on conserving
their rainforest habitat and restricting hunting, especially night hunting.
But studies of their propagation and management are also imperative.
In particular, research is warranted on various aspects of their
husbandry, such as enclosure design, space requirements, and health.
A special research need is to understand the animal's nutritional
requirements and to develop diets for use in captivity.
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OCR for page 298
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Representative terms from entire chapter:
malayan mouse
