Water Deer Distribution - A Note on Spread

It's often commented that water deer have spread much more slowly than other introduced cervids, such as sika or muntjac, and this certainly seems to be the case in Britain, although the pace appears to have increased in recent years. The UK Mammals report by the Tracking Mammals Partnership, published in 2005, noted that while water deer had doubled their range since 1969, that range remained the smallest of any deer species in the country. Subsequently, in 2008, Alistair Ward and colleagues calculated that the average annual increase in water deer distribution since their introduction had been only 2%, but an astonishing 22% of that total occurred between 2002 and 2007. Indeed, the number of 10 km (6-mile) squares occupied by water deer had increased from 23 in 1972 to 54 in 1998 and 187 in the most recent (2016) analysis, although 54 squares where they were recorded in 2007 or 2011 did not yield records in 2016, while their presence was recorded in 38 squares for the first time in 2016.

Some of this increase is attributable to the coarse scale over which the country is divided for the analysis, giving the impression that the range is continuous when it is not, and to the fact that more people recognise water deer and report their sightings now than in the 1970s and 1980s. Equally, however, the deer appear to have prospered across a large area of suitable habitat in coastal and Broadland Norfolk and Suffolk, allowing them to colonise rapidly. In his 2019 book Muntjac and Water Deer, Arnold Cooke notes that the situation is slightly different in Buckinghamshire, where animals appear to be settling more quickly and expanding their core distribution south-west. Cooke suggests this may reflect farmland densities being higher than in East Anglia, making small populations less likely to die out or move on. Overall, the 2016 data point to a general expansion westward from the core range of East Anglia and the northern Thames Valley (i.e., Bedfordshire and Buckinghamshire) into north-eastern Oxfordshire. (See also: Maturity and Dispersal for discussion of behaviour in animals introduced to new areas.)

It seems probable that large sporting estates in Bedfordshire, Buckinghamshire, and East Anglia that breed significant numbers of water deer generate spillover into local populations, supporting persistence in those areas and driving colonisation in neighbouring ones. Certainly, in an article in Sporting Rifle in 2014, Paul Childerley considered that in Bedfordshire "keepered ground has been the key to the CWD's survival and subsequent establishment in the wild", owing to fewer foxes and night patrols limiting poaching and coursing. Similarly, in a March 2025 episode of the YouTube channel Hunt, Gather, Cook filmed at Raveningham Estate in Norfolk, Conservation Manager Adam Gage noted that water deer numbers had "exploded" in the past eight or nine years, partly in response to predator and vermin control. Indeed, in their 2009 book Wild Deer in Britain, Roy Harris and Ken Duff proposed that:

"Another possible explanation for their relative lack of success as wild animals is that they suffer crippling losses to predators."

Based on data collected by Arnold Cooke and Lynne Farrell, water deer also appear to have more specific habitat requirements and a more restricted diet than other species. Furthermore, based on my observations and those of both Richard Champion at Whipsnade and Gérard Dubost at the Branféré Zoological Park in France, they are much more sensitive to disturbance than muntjac. That said, reports from stalkers and landowners in East Anglia suggest that while spread outside the species' known range may be slow, multiplication within it and infilling of existing range has increased significantly in the past decade or so. In his 2025 paper in the Huntingdonshire Flora & Fauna Society Annual Report, Cooke notes variation in spreading at the county level, with proliferation in the Broads promoted by continuous expanses of suitable habitat compared with his observation sites in Cambridgeshire. Changes in climate and in farming to accommodate it, along with wetland rewilding projects, may also help water deer expand within their current range and push beyond it. In his article in the May 2024 issue of the Deer Specialist Group Newsletter, John Jackson suggested:

"The explanations for the surge in the population and spread of this small ungulate are complex, cumulative and speculative. Climate change may be one including warmer summers and milder yet damp winters. Farming in Britain has also changed and evolved. The staple cereal crop in the region is wheat (Triticum aestivum). Traditionally that was sown in the spring. Over the last few decades, it is generally planted in the autumn for harvesting the following summer. That change in agricultural practice means that there are now fresh green cereal shoots for this deer to feed on at a once challenging or lean time of year when quality grazing and cover were in short supply."

In their 2010 expansion modelling, published in Diversity and Distributions, Pelayo Acevedo and colleagues predicted that water deer could potentially expand significantly beyond their current range, based on environmental favourability – as far as Wiltshire in the west, North Yorkshire in the north, and throughout England's eastern quarter. The researchers also suggest the potential for outlying populations in parts of south and central Wales, Kielder and the Scottish borders, Perthshire, and north-east Inverness-shire through to the Moray coast.

It seems likely that some ongoing conservation projects are also supporting this expansion. The Methwold project in Norfolk may, for example, help provide a reservoir for water deer if not properly managed, and/or help connect pre-existing habitat and populations to promote expansion within the county. Likewise, the Bedford and Milton Keynes Waterway Park -- a significant project aimed at connecting Bedford to Milton Keynes by creating 25 km (16 miles) of linear park with a navigable waterway at its core -- will inevitably provide a corridor for water deer. More broadly, the general drive by successive governments to promote set-aside and the active planting of wildflower strips and woodland to boost pollinator numbers is likely to have a knock-on effect for all deer, including Hydropotes. Michael Anker, Project Lead of the Norfolk Deer & Wild Venison Strategy, told me in December 2025 that these wildlife conservation projects have provided ideal habitat for water deer both to live in and to disperse through, resulting in not only a significant increase in numbers but also a rapid spread into areas where they have not previously been recorded. Certainly, my experience in Norfolk has been that deer are drawn to set-aside field margins, which often contain a mix of species including oilseed rape, scorpionweed (Phacelia), clary sage (Salvia sclarea), and kale (Brassica oleracea), along with native wildflowers.

References

Acevedo, P. et al. (2010) Assessing biogeographical relationships of ecologically related species using favourability functions: a case study on British deer. Diversity and Distributions. 16: 515–528.

Battersby, J. (ed.) (2005). UK Mammals: Species Status and Population Trends. First Report by the Tracking Mammals Partnership. JNCC/Tracking Mammals Partnership, Peterborough.

Childerley, P. (2014). Herd reduction. Sporting Rifle. (107):90-92.

Cooke, A. (2019). Muntjac and Chinese Water Deer: Natural history, environmental impact and management. Pelagic Publishing, Exeter.

Cooke, A.S. 2025. Population expansion of Chinese water deer in the former county of Huntingdon and Peterborough, 2014-2025. Huntingdonshire Flora & Fauna Society Annual Report. 77: 59-52.

Harris, R.A. & Duff, K.R. (2009). Wild Deer in Britain. Collins & Dean Press, Somerset.

Jackson, J. (2024). An endangered deer in the wrong place? DSG Newsletter. (35): 43-45.