Chinese Water Deer

(Hydropotes inermis)

INTRODUCTION

There are two known subspecies of water deer. Hydropotes inermis inermis, which is native to China along the Yangtze River, is the type that can be found in Great Britain and on which these notes focus. The other subspecies of water deer is Hydropotes inermis argyropus which is found in Korea. Hydropotes inermis inermis is said to be the most primitive living member of the Cervidae family. This is because the buck carries large canine teeth or tusks and has no antlers, characteristics which other deer have evolved beyond. The Musk Deer (Muschus) also has no antlers and large canines, but taxonomists would describe it as a tragulid rather than a cervid – it has a gall bladder, a three-chambered stomach, an immobile upper lip, unspotted young and no scent glands on its legs. These technical differences make the Chinese Water Deer a biologically important and fascinating animal.

The Chinese Water Deer is the least common of our wild deer population and it is often said we know little about it. This is invariably a reflection of its limited geographic distribution. There is an ongoing study project at Woodwalton Fen Nature Reserve in Cambridgeshire which began some 24 years ago. Also, Whipsnade Wild Animal Park has produced two detailed papers on Chinese Water Deer which, along with a recent ecological study on the species in its native China, provides a considerable database for those looking into the subject in depth.

HISTORY AND DISTRIBUTION

Chinese Water Deer were first introduced into this country in the 1870s and were kept in London Zoo. In 1896 they were transferred to Woburn Abbey, Bedfordshire, with further additions being imported and added to the stock. Breeding was successful and by 1913 the numbers totalled 126. Detailed records ceased at the outbreak of the First World War but in 1935-36 it was recorded that 180 deer died, proof of their continued breeding. In 1929 and 1930, 32 deer were transferred from Woburn to Whipsnade, also in Bedfordshire, and released into the park. By 1933 a census estimated that the population had risen to about 200. But during the next twelve months it is believed that approximately 140 of the deer died – there is no information suggesting a link to the decline in the Woburn Abbey population. By 1936 the population swing was again positive, with 115 deer occupying an area of 1.7 hectares. It is thought that the current Chinese Water Deer population at Whipsnade is over 600 whilst at Woburn it is probably in the region of 250 plus.

Our present feral population derives from a number of deliberate releases, however the majority have descended from escapees. It is suggested that government officials working at Woburn during the Second World War were less than diligent in closing the gates! The majority of the wild Chinese Water Deer population still resides in close proximity to Woburn Abbey. It appears that the deer’s strong preference for a particular habitat – tall reed and grass areas in rich alluvial deltas - has restricted its potential to colonize further afield. The main area of distribution is from Woburn, east into Cambridgeshire, Norfolk and Suffolk, and south towards Whipsnade. There have been small colonies reported in other areas, but these do not appear to have survived. Isolated sighting are probably due to individual releases or escapes from private collections. Twelve years ago there was a Chinese Water Deer killed on a road in Somerset but there have been no further sightings there.

DESCRIPTION

Adult male Chinese Water Deer (bucks) stand in the region of 50-55cm at the shoulder, with the females (does) about 3-5cm shorter. Their live weight ranges between 11-13.5kg for bucks and 8-11kg for does. The adult water deer can perhaps best be visualized as being between the sizes of a Roe deer and a Muntjac. The hind legs of the Chinese Water Deer are longer than the fore legs which causes the rump to be carried higher than the shoulder, without appearing hunched up. It is this high rump feature which assists in distinguishing these deer from Muntjac does. However, they can be more easily mistaken for Roe does and vice versa. Chinese Water Deer do not have antlers and both genders grow canine teeth or tusks, the female’s being short and the male’s being much longer and visible. The ears are large and prominent. The eyes and nose resemble black buttons, giving a facial appearance similar to a teddy bear, a feature particularly noticeable in young animals as well as in bucks in winter coat.

Pelage in summer is a rich chestnut to ginger red, whilst the winter coat is a peppery gray-brown to pale brown. The tail is inconspicuous, being 5-10cm long, and there is no white on the rump or caudal patch unlike Roe and Muntjac, however the caudal patch may be paler than the rest of the coat. In winter coat, water deer sometimes have a shiny looking back. This is due to light reflection from broken hairs which are hollow to provide insulation and are translucent with the exception of the colored tip. This appearance is also often observed in Roe deer during these winter months. In April and May the deer shed their winter coat as a sleek summer coat grows through, taking on an unkempt appearance as their old coat falls away leaving what seem to be bald patches. The deer will retain their summer pelage until the autumn when the winter coat re-grows. Facial coloration differs between sexes; mature does sometimes have a pale whitish-gray band on the muzzle whereas the bucks have a darker gray-black coloration in the same area. Another distinguishing feature between the sexes is the neck is noticeably thicker in mature bucks. Like other deer, Chinese Water Deer have scent secreting glands for territory marking: they have small preorbital glands and interdigital glands, but on their hind legs only. They are unique amongst deer in having inguinal (lit ‘of the groin’) glands.

TUSKS

Canine teeth or tusks are grown by both bucks and does and these usually erupt in the autumn of the deer’s first year at approximately 6-7 months of age. Bucks’ tusks are considerably longer than does’. By early spring the recently erupted tusks reach approximately 50% of their final length, which averages 56mm. A doe’s tusks are much shorter and reach an average length of only 6mm. As the tusks develop, the root remains open until the deer is about eighteen months to two years old. When fully grown, only about 60% of the tusk is visible below the gum. The tusks in the buck are hinged and loose in their socket which gives muscular control in order to angle them backwards to facilitate grazing, or project them forward when fighting other bucks. Tusks are used whilst fighting in both a stabbing and a ripping manner and it is common to see older bucks with broken tusks resulting from this as well as animals with torn ears and long scars on body and neck. Fights are seldom fatal but may leave the looser considerably debilitated.

Tusks are concave on the inner side and are extremely sharp on both edge and point. The edge is maintained by being constantly burnished on the inner side by rubbing against the lips. This rubbing can wear away the tusks exposing the inner cavity of the tooth, providing an indicator of age. Bucks also rub young saplings between their tusks and face (preorbital scent glands) when marking territory, but this action is far less severe than the scent marking fraying of Muntjac, causing less visible sign of the local population.

HABITAT AND FEEDING

The natural habitat of Chinese Water Deer would normally be that associated with areas of rich alluvial deltas, but the habitat adopted in this country is wider ranging than that in their native land. Here they are found in woodland, grassland, arable fields and, not surprisingly, reed beds and fen land. When excess water leads to such high water table areas as they prefer flooding, the deer must move to find alternative feeding. Whilst relatively adaptable, reliance upon a specific habitat and, in the early months of life, a vulnerability to predation and as well as a high mortality rate probably play a key determining role in their limited distribution in England.

Chinese Water Deer are ruminants like other cervids. As with Roe, they have a simple digestive system that is based on selective, high nutritional feeding rather than more coarser bulk feeding. They feed in bouts of 20-45 minutes depending on the availability and quality of food. The remainder of the time is spent in ruminating or chewing the cud. Feeding occurs during both day and night, but the deer are most active around dawn and dusk. When not seen out in the open they can be assumed to be browsing available food in cover. Bramble is a particularly important food source in winter months. They can be categorized as selective grazers, with the majority of food intake comprising grasses, herbage and sedges. Crops are also eaten, carrot tops and spilled potatoes being a favorite. Browsing, as mentioned earlier, does occur but it is mainly restricted to leaves rather than woody vegetation. However, like all deer, they will exploit the best available food sources.

ANNUAL CYCLE

Between May and June the doe gives birth to up to four fawns, although two would be normal. Chinese Water Deer are capable of multiple births, with as many as seven fetuses previously recorded in a pregnant doe in China, but the highest number on record in England is four. At birth the fawns weigh approximately 1kg and gain 0.1kg a day over the next few weeks. Despite such a high birth weight for a deer weighing not much more than 10kg when fully grown, mortality at this stage can be high. The doe cleans up all signs of the birth and licks the fawns clean to remove any scent that might attract predators, especially foxes. The young are concealed in long grass or similar vegetation where they spend the first few weeks whilst the doe returns to suckle them at intervals. They may be hidden together but are more probably placed closely apart. Fawns are able to stand within an hour of birth and have been known to walk short distances in their first day. They are weaned by three months of age and they will have been nibbling grasses from very early on, reducing the intake of milk. Fawns are light brown with white spotting at birth and the spots disappear after about 8 weeks. Groups of fawns are often seen together as they mature though they are not necessarily related. By six months of age they are independent and approaching sexual maturity. It is at this time, as the rut approaches, that the young are dispersed or driven off by mature animals.

Rutting begins in late November, although amongst park or enclosed deer it might be earlier, reaching a peak in December and sometimes extending into January. The deer are now all in winter pelage and territories have been established. Copulation is brief, taking only a few seconds but with repeated mountings. Mounting is preceded by a buck’s courtship of a doe, usually but not necessarily within the bucks territory. The doe is checked for being in oestrus by the buck approaching with low, out-stretched neck, rotating his head which produces a slapping of the ears. Young bucks are sexually mature in their first year but in areas with an established population are rarely successful at mating. Does in their first year may conceive and fecundity is similar to that in older animals, but in heavily populated areas does will usually conceive in their second year. The gestation period ranges between 165 and 210 days, but the average of 180 days reflects the peak of the rut in early December when the majority of fertilized ova become implanted. The sex ratio of fawns is recoded as being more or less 1:1 bucks and does.

SOCIAL STRUCTURE

Depending on population density, Chinese Water Deer are considered solitary animals which interact closely only during the rutting months. Bucks are extremely territorial and the does also tend to retain a home range which may overlap outside the rutting months. There is evidence that does are territorial immediately prior to, during and after the fawning season and they have been recorded fighting. Whilst it is common to see a number of deer feeding in close proximity, they are going about their own business and will disperse in different directions, except fawns which will follow their dam. All ages and sexes have been observed running and frolicking in play, but it is more commonly seen in young fawns in their early months of life.

During the rut bucks are very aggressive in defending their territory, which they mark by scrapes and scent rubbings. They also mark territorial boundaries with piles of dung pellets or fumets, which at this time of year are reduced in size so as to produce more to excrete in these social marking areas. Encounters with other bucks usually begin with a stiff-gaited, threatening posture which is followed with parallel walking as if sizing each other up. If neither retreats at this juncture then a chase will ensue with the chasing buck making a clicking sound. Should both bucks decide not to submit, then a fight will probably occur. This takes the form of dancing around each other trying to land blows with their tusks and continues until one animal is injured or decides it is out-matched. Evidence of these encounters in the form of tufts of hair torn out in a fight can be found on the ground in an occupied and actively defended territorial area.

VOICE AND CALLS

The Chinese Water Deer is capable of emitting a number of sounds. The main call is a bark and this has more of a growl tone when compared with the sharper yap of a Muntjac. The bark is used as an alarm and water deer will bark repeatedly at people and at each other; in some cases they just bark for reasons beyond our knowledge. If challenged during the rut, a buck will emit a clicking sound. It is uncertain how this unique sound is generated, although it is possibly by using its molar teeth. During the rut a buck following a doe will make a weak whistle or squeak. The does emit a soft pheep to call to their fawns, whilst an injured deer will emit a screaming wail.

SUMMARY

Having been in this country longer than the Muntjac deer and having the potential of a high fecundity rate, the question of their very limited expansion within England immediately raises itself. It is established that they have some propensity to adapt from their native habitat to other land types, yet the spread of Chinese Water Deer is still only forecast at 1km a year within East Anglia. Is it because there have been fewer releases or escapees from fewer private collections than the Muntjac has enjoyed? Is our climate more restrictive than we believe? Is the mortality rate in a severe winter enough to retard displacement by enough years to produce a status quo? Is it less adaptable in habitat than other, more notably successful non-indiginous British deer? Whatever the answers are, in the Chinese Water Deer we have a biologically significant deer and a charming addition to our wild deer population. It deserves to be cherished, not least because in their native land they are ‘red listed’ as an endangered species.