My first encounter with Chinese water deer was whilst driving a (wildlife) route to get my baby daughter to sleep, 30 years ago a car journey worked when other methods failed! I lived in Luton at the time and this drive, up to Woburn, along county lanes allowed me to record and observe muntjac, hares, foxes and upon this occasion a few Chinses water deer. The surrounding habitat was one of large arable fields and grassland openings, certainly not where you would expect to see a marshland specialist. However, Chinese water deer live out in these fields hiding in the tall vegetation in the summer and occasionally using woodland for cover in the winter. They are easy to tell apart from the similar sized muntjac which tend to stay close to hedgerow or woodland edges unlike the water deer who are found in the middle of the fields. As for morphology, both have a slight slope to their backs toward the head which is more pronounced in muntjac. Additionally, water deer are generally lighter in colour and have a noticeable marking on their rump which helps distinguish them from muntjac which hold their tail up showing a white underside. The real difference is when you see the face full on and get the feeling that a teddy bear is looking at you, with its fluffy ears and black nose. Ignoring, of course, the large tusks jutting out below the bottom jaw.
There is just one species of Chinese water deer (CWD) which is native to China and Korea, but their numbers are falling as their preferred habitat of grassy wetlands and river margins is being lost to land improvement schemes for farming. They have been listed as vulnerable by the International Union for the Conservation of Nature (IUCN) Red List since 2015, but the UK population is expanding and is currently estimated at 3,600 and growing. There is thought that our British Chinse Water Deer may help repopulate their native lands.
They made their first appearance at London Zoo in 1873 and were not released into the deer park at Woburn until 1896 and again in 1913. Additionally, some were introduced into the grounds of Whipsnade Zoo in 1929 and many other animal collections throughout Britain. They were first recorded as wild in Buckinghamshire in 1945. This was followed by other escapees which had become free living in Bedfordshire in 1954, and Norfolk in 1968, Suffolk 1987 and Cambridgeshire 1971. Higher numbers are found in Norfolk as the broads and fens are similar to their native habitat, this allowed them to spread out into Suffolk (1987) and later Cambridgeshire (1971) along with some still escaping from private collections.
I sometimes still call in to check on the population at the Bedfordshire, Buckinghamshire border, driving my old route and seeing the deer in numbers of up to 20 in one field. The large group numbers tend to be in the winter months as females share territories when food is scarce and the bucks are in rut. Males are aggressive to each other and tend to be solitary, whilst females will form small groups throughout the year. Seeing up to five individuals in a group could just be mother with 4 young although 2 is the normal birth rate. This population has grown over the years pushing out in all areas surrounding Woburn but more successfully to the south east and along the Chilterns into Hertfordshire help by escapees from the established Whipsnade population.
These photos are some records from Lincolnshire, Kent Surrey and Sussex and elsewhere but we do not know how established these populations are. To fully understand the impact of Chinese Water Deer on the wider environment we need to build on our knowledge of how widely spread they are across the UK. This is because, although they do not fray trees like other deer species, there is localised crop damage to consider and the road traffic accidents they cause. You can help us to do this by recording your sightings on the Mammal Society’s Mammal Mapper app.
This blog comes from mammal expert Derek Crawley. Derek is a valued active member of the Mammal Society, he is Vice Chair and the Training Committee Chair. Additionally, he is the current Chair of the Staffordshire Mammal Group and a Regional Coordinator for the National Harvest Mouse Survey. All photos in this blog were taken by Derek himself.