Chinese water deer

(Hydropotinae)

Class Mammalia

Order Artiodactyla

Family Cervidae

Thumbnail description
Small, dainty, antlerless deer with large ears and tusks; cold adapted and territorial; a saltor and hider in dense vegetation

Size
Height 19.6–21.6 in (50–55 cm) at the shoulder; weight 33 lb (15 kg)

Number of genera, species
1 genus; 1 species

Habitat
Riparian vegeation such as swamps, reedbeds, and grasslands

Conservation status
Lower Risk/Near Threatened

Distribution
Coasts and river valleys of eastern China, Korea; introduced in France and England

Evolution and systematics

In the structure of their skulls, brains, appendages, genetics, and the spotting pattern of their fawns, Chinese water deer are closely related to the European roe deer (Capreolus capreolus) and moose (Alces) of the New World deer subfamily. Males lack antlers, but possess large, protruding upper canines with which they fiercely defend resource territories in fertile flood plains. Together with small cheek teeth, small and simple brains, their selection of highly digestible plant foods and their escape behavior via rapid, long bounds followed by hiding, indicate a very primitive or ancestral condition among deer.

The water deer first appeared some 30 million years ago in the Oligocene. However, it may be secondarily primitive. It may have lost its antlers in favor of large tusks while reverting back to defending small, but resource-rich territories. A similar evolutionary reversal reducing antler size in favor of tusks has been identified in the muntjacs among the Old World deer. Here, phylogenetically young species defending small territories have small, simple, or rudimentary antlers compared to phylogenetically old species with large, complex antlers found on large territories in relatively infertile landscapes. The water deer is unusual in that its primitive adaptations are normally associated with warm climates. However, it is adapted to cold-temperate seasonal climates with frost and snow. It is characterized by an exceptionally high reproductive output and early sexual maturation, which matches the ecological opportunities and dangers in flat valleys with large, flooding rivers. The genus consists of a single species, Hydropotes inermis, and two subspecies: Hydropotes inermis inermis, found in eastern China, and Hydropotes inermis argyropus of Korea.

The taxonomy for this species is Hydropotes inermis Swinhoe, 1870, Kiangsu, China.

Physical characteristics

The water deer is a small, elegant animal with narrow pectoral and pelvic girdles, long legs, and a long, graceful neck. Its powerful hind legs are longer than its front legs, so that its haunches are carried higher than the shoulders. It runs with rabbit-like jumps. In the groin of each leg is an inguinal

gland used for scent marking; this deer is the only member of the Cervidae to possess such glands. The short tail is no more than 1.9–3.8 in (5–10 cm) in length and is almost invisible, except when it is held raised by the male during the rut. This deer characteristically stands alert, with its head held high and its ears erect.

The most striking features are the long, curved upper canines in the male, measuring 2.1 in (5.5 cm) on average in length. At the end of the male's first winter, his canines will be about half their full size; final length is reached after about 18 months. These canines are held loosely in their sockets, with their movement controlled by facial muscles. The male can draw them backwards out of the way when eating. In aggressive encounters, he thrusts his canines out and draws in his lower lip to pull his teeth closer together. He then presents an impressive two-pronged weapon to rival males. The female, by comparison, has tiny canines measuring just over 0.2 in (0.5 cm).

In the fall, this deer's red or reddish brown summer coat is gradually replaced by a thicker, coarse-haired winter coat that varies from light brown to grayish brown. Neither the head nor the tail poles are well differentiated as in gregarious deer; consequently, this deer's coat is little differentiated.

Distribution

Formerly widespread in eastern China, the Chinese subspecies is now largely restricted to the lower reaches of the Yangtze River, coastal Jiangsu province, and islands of Zhejiang.

Feral populations dating to the mid-twentieth century are well established in southern England, and highly localized populations are found in France. The Korean subspecies is thought to have a wide distribution, but evidence is lacking.

Habitat

True to its name, the water deer occupies fertile river valleys as well as well-vegetated lake shores and coastal areas where tall reeds, rushes, sedges, and grasses provide it with cover. A proficient swimmer, it can swim several miles to make use of river islands.

Seasonal flooding of river deltas forces water deer to higher ground. They head up to hill grassland, where they venture into open fields, providing there is tall vegetation within easy reach. Other seasonal movements in search of better grazing may also be undertaken.

Behavior

Apart from during the rutting season, water deer are solitary animals, and males are highly territorial. Each male marks out his territory with urine and feces. Sometimes a small pit is dug and it is possible that in digging, the male releases scent from the interdigital glands on its feet. The male also scent-marks by holding a thin tree in his mouth behind the upper canines and rubbing his pre-orbital glands against it. Males may also bite off vegetation to delineate territorial boundaries.

Confrontations between males begin with the animals walking slowly and stiffly towards each other, before turning to walk in parallel 32–64 ft (10–20 m) apart, to assess each other. One male may then succeed in chasing off his rival, making clicking noises as he pursues his vanquished foe. However, if the conflict is not thus resolved, the males will fight. Each tries to wound the other on the head, shoulders, or back, by stabbing or tearing with his upper canines. Numerous long scars and torn ears seen on males indicate that fighting is frequent. Tufts of hair are most commonly found on the ground in November and December, showing that encounters are heavily concentrated around the rut.

Females do not seem to be territorial outside the breeding season and can be seen in small groups, although individual deer do not appear to be associated; they will disperse separately at any sign of danger. Females show aggression towards each other immediately before and after the birth of their young and will chase other females from their birth territories.

Communication between these solitary animals generally takes the form of low growling barks. They are certainly used as calls of alarm, but they are also directed repeatedly at other deer or humans for reasons that are unknown.

Feeding ecology and diet

This species spends roughly half its waking hours feeding, with 20 minute periods broken by spells of rest or rumination. Peak feeding activity is recorded around dawn and dusk. The water deer feeds at night too, although it is not known how much time is spent on nocturnal foraging. It is often observed grazing in the open, where it relies on good eyesight and smell to detect danger.

The water deer is a concentrate selector, avoiding low-grade food, but the degree of selectivity appears to vary between locations. One study in China of water deer rumens showed that the leaves of herbs made up 59% of the diet, with grasses and sedges comprising 24% and woody material 17%. Another study showed herbs constituted 93% of its diet.

Reproductive biology

During the annual rut in November and December, the male will seek out and follow females, giving soft squeaking contact calls and checking for signs of estrus by lowering his neck and rotating his head with ears flapping. Scent plays an important part in courtship, with both animals sniffing each other.

Mating among water deer is polygynous, with most females being mated inside the buck's own territory. After repeated mountings, copulation is brief. Gestation is normally around 180 days.

Water deer have been known to produce up to seven young, but two to three is normal for this species, the most prolific of all deer. The female often gives birth to her spotted young in the open, but they are quickly taken to concealing vegetation, where they will remain most of the time for up to a month. During these first few weeks, fawns come out play. Once driven from the natal territory in late summer, young deer sometimes continue to associate with each other, later separating to begin a solitary existence.

Conservation status

Although classified as a protected species in China, levels of hunting permitted during the 1990s did not appear to be sustainable. Population estimates at that time suggested a figure of no more than 10,000 individuals, yet this figure was given by the government as the annual tally hunted legally. Scientists also report at the beginning of the twenty-first century increased levels of poaching in eastern China. The IUCN lists the species as Lower Risk/Near Threatened.

Water deer are suffering increasing losses of habitat through conversion of wetlands to agriculture and aquaculture; significant losses have been recorded around the Yancheng coastal wetlands, one of the main strongholds. Construction of the Three Gorges Dam may have a huge impact on water deer habitats along the Yangtze River and associated waters. Ironically, numbers of this subspecies in southern England continue to expand following accidental introductions in the 1940s. It is feasible that numbers there may eventually exceed those in its native China.

Although the status of Siberian water deer (Hydropotes inermis argyropus) in Korea is not well documented (listed as Data Deficient), this subspecies is thought to be widespread and abundant. Proposals to establish a huge national park in the demilitarized zone between North and South Korea show that positive action that would protect this deer is being considered.

Significance to humans

This deer's tendency to remain standing still in the open makes it an easy target for hunters, both for meat and for its stomach colostrum, a prized ingredient in folk medicine. Formerly, it was viewed as a crop pest in China and slaughtered as such until rarity and legal protection ended this practice. Rapid growth, early maturity, and high fecundity make water deer considered for domestication. However, livestock farmers are deterred by this solitary species' reputation for territorial aggression.

Resources

Books

Cooke, A., and L. Farrell. Chinese Water Deer. Fordingbridge, UK: The Mammal Society and British Deer Society, 1998.

Geist, V. Deer of the World. Mechanicsburg, PA: Stackpole Books, 1998.

Macdonald, D. The New Encyclopedia of Mammals. Oxford: Oxford University Press, 2001.

Office of International Affairs. Microlivestock: Little-known Small Animals with a Promising Economic Future. Washington, DC: National Academy Press, 1991.

Putman, R. The Natural History of Deer. Ithaca, NY: Comstock Publishing Associates, 1989.

Organizations

British Deer Society. Burgate Manor, Fordingbridge, NH SP6 1EF England. Phone: 1425 655434. Fax: 1425 655433. E-mail: [email protected] Web site: <http://www.bds.org.uk>

Derek William Niemann, BA