Water Deer Population & Abundance - England

Outside of Arnold Cooke and Lynne Farrell's comprehensive study of water deer in Cambridgeshire, we have relatively few data on their population and density across their feral range in Britain. Most farmland populations are managed in some way, such that the density is probably more a result of desired numbers than the carrying capacity. Where direct management of the deer is lower, such as in fenland nature reserves, populations fluctuate according to land management practices. Cooke gave a nice example of how habitat management can have significant ramifications in his 2019/20 Deer Surveillance Report for Woodwalton Fen:

"The population increased [from 2006] up until 2010/11 because of the presence of elephant grass on Mormon land for several years, but then decreased even more dramatically due to loss of the crop and to inclement weather conditions in some years. I suspect that the population is currently at the highest level the landscape can sustain, but could change in the longer term if there were major management changes in the reserve or on the farmland – and could decrease in the short term if there was extreme weather."

While we know from the above study, Gérard Dubost's data collected at Branféré Zoological Park, and census information from Whipsnade that populations can build very rapidly, doubling every 1.27 years in good conditions, variations in land management may help explain how water deer populations have failed to persist in some spots, disappearing a few years after their initial colonisation. This is presumably part of the explanation for water deer showing the lowest expansion of any of our introduced species since 1972 that Adrian Ward noted in his 2005 review.

Density estimates are highly context-dependent, varying with habitat, season, and disturbance. Within any given area, pockets will exist that attract and support higher numbers than others, while biotic and abiotic factors may serve either to concentrate or disperse deer. The abundance of water deer on an undisturbed spring grass crop, for example, may be substantially higher than in nearby woodland, or in the same area during autumn when harvesting and gamebird shooting are underway. In Buckinghamshire, Sharon Scott has observed that counts in an area can change markedly when organised shoots are in operation, with animals displaced to adjacent ground. Densities may also be higher on nature reserves than on surrounding farmland, particularly where that farmland carries livestock (sheep, especially). The time of year matters too: higher concentrations are often recorded during the winter rut.

The values that follow are therefore intended to illustrate the range of densities recorded in England. They should not be taken to apply to other habitats, treated as a basis for county or national extrapolation, or assumed necessarily to reflect the current situation.

The highest density ever recorded for England appears to be at Whipsnade during the rut of 1988, when Stefan Stadler estimated the population stood at 7.6 per ha (760 per km²) – albeit a semi-free-ranging captive population. During the winter of 2019/20, Arnold Cooke estimated the water deer population on Woodwalton Fen reserve at around 0.8 per ha, though the presence of elephant grass (Miscanthus sp.) on an adjacent farm had resulted in higher densities for several years, peaking at just over 1 per ha (100 per km²) in one winter, before its removal in 2011. In their chapter in the 2008 Mammals of the British Isles: Handbook, Cooke and Lynne Farrell gave average densities at both Woodwalton and on the Norfolk Broads of around 0.1 per ha (10 per km²), and in Muntjac and Water Deer, Cooke noted that density was maintained at 0.09 per ha (9 per km²) on one area of farmland in Bedfordshire.

Higher densities have been estimated elsewhere. Counts by the Bedfordshire Natural History Society suggested between 0.2 and 0.5 deer per ha during the early 1990s, and in an article in Country Life in October 2024, Paula Lester reported that the water deer population on the Beckerings Estate in Bedfordshire was maintained at around 1,000 animals; an average density of 1.5 per ha (150 per km²). No published data exist, but some of the game estates in the Woburn and Norfolk regions may exceed this.

Recent surveys across the Norfolk Broads suggest that densities are considerably higher now than even a decade or two ago, though these have been conducted using drones, which are likely more accurate than earlier methods. A thermal drone survey on one Norfolk estate in 2023 identified 211 water deer at an overall density of 0.5 per ha, rising to around 1 per ha on the grazing marshes. The impact assessment published by the Broads Authority in 2025 -- based on drone surveys conducted over 20,350 ha in February of the previous year -- offers limited granularity but similarly points to high densities. In that report, Mike Harding recorded a mean site density of 0.08 per ha (7.7 per km²), the highest of the four deer species recorded. Of the 3,445 deer counted across the survey area, 1,571 (nearly 46%) were water deer, a striking indication of how dominant the species has become in the Broads landscape. Localised densities exceeded 1 per ha in the most favoured areas. In April 2026, Ben Harrower, Director of BH Wildlife Consultancy and part of the team conducting the drone surveys, told me they have recorded densities in the Waveney River Valley, which straddles the Norfolk-Suffolk border, as high as 1.3 per ha, the highest confirmed wild density for the species in England (likely also the world) to date.

In terms of overall numbers, most current published figures for England are likely to be significant underestimates. In 1995, The Mammal Society estimated the water deer population at around 650. The Society announced the population had risen to about 2,100 -- some 1,500 of which were free-living in England -- at their Autumn Symposium on British Mammal Populations in 2004. It's probably this 1,500 figure to which the Tracking Mammals Partnership were referring in their 2005 report UK Mammals, when they wrote that there were "less than 2,000" water deer in England. In his 2009 assessment in International Urban Ecology Review, however, Arnold Cooke estimated around 4,000 living wild in England, based on available distribution and density data, and two years later, writing in Deer, revised this upward to around 7,000, drawing on a combination of local and national distribution data and his own observations in Cambridgeshire.

More recently, the Mammal Society's Britain's Mammals 2018 gave a population range of 200 to 143,000, with a "highly tentative estimate" of 3,600. These figures drew primarily on a modelling analysis led by Simon Croft at the Animal and Plant Health Agency, published in 2017, and are sufficiently wide to be of little value. Croft and his colleagues acknowledged significant limitations in that analysis: the estimates were based on outdated density data, and the 3,600 figure covered only arable, improved, and rough grassland, with no wetland density information included.

In Muntjac and Water deer, published in 2019, Cooke provided his updated opinion that the population was likely in the range of 5,000 to 10,000 in England. During a chat over coffee in 2022, Arnold told me that he thought England's wild population was "closer to 10,000 than it is to 1,000 or 100,000", very tentatively suggesting the number was probably 7,000 to 8,000 animals. In his contribution to the Huntingdonshire Flora & Fauna Society Annual Report, published in 2025, Cooke upgraded this to 18,000, noting that the actual figure may be substantially higher. While Cooke's 18 thousand figure remains the most recent published estimate for England of which I'm aware, recent thermal done surveys carried out by BH Wildlife Consultancy, in collaboration with The Forestry Commission, tentatively imply numbers may indeed be significantly above even this, perhaps into the mid tens of thousands, but data are still being gathered and processed.

If we take the appraisal that there were "no more than 5,000 water deer in China" -- given to Richard Fautley in 2011 by Min Chen, a biologist at East China Normal University -- as broadly reflecting the current situation, the UK population would appear to be of real conservation significance. Both Fautley, in his PhD thesis, and Rory Putman and colleagues, in their 2021 paper in the Zoological Journal of the Linnean Society, proposed that the 7,000 deer in Cooke's 2010 estimate, together with around 500 animals in captivity in Britain, probably accounted for roughly 40% of the global population.

In my view, the number currently held in captivity in Britain is probably substantially fewer than 500. Whipsnade's 2025 inventory suggests 40-50 water deer in their collection; even allowing for some underestimate, perhaps 60 is a reasonable working figure. Woburn's numbers are harder to pin down, as the Abbey doesn't release its official census data, but one of their managers told me in 2014 that they aim to maintain around 30 in the park. Houghton Hall is similarly unknown, though its parkland setting is comparable to Woburn's and the numbers are perhaps in the same range. As of May 2025, Watatunga held around half a dozen individuals, and a pair reside at the Wildwood Trust in Kent. Britain's captive population, in my estimation, is therefore unlikely to exceed 250 animals and is probably closer to 150.

If we accept Min Chen's estimate for China and Cooke's lower 2019 estimate for England at face value, the UK population (wild and captive combined) may account for at least half of the animals present in both countries, rising to nearly 80% on Cooke's 2025 figure. If the South Korean Ministry of the Environment's remarkable 2018 extrapolation of at least half a million animals, and Yury Darman and Gleb Sedash's 2020 estimate of no more than 170 animals in Russia, are correct, however, the UK's contingent represents perhaps 1-4% of the global total*, depending on which English estimate is used. Should the thermal surveys discussed above end up revealing significantly higher numbers than earlier estimates -- as I suspect they will -- Britain's water deer population may prove to account for 20% or more of the global total.

Whatever proportion of the world population Britain's deer ultimately represent, their conservation significance seems hard to dispute. It is already clear that England holds substantially more water deer than China at present, and Putman's data point to a genetic lineage here that is now extinct in the wild in its native range.

Bibliography

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.

Darman, Y.A. & Sedash, G.A. 2020.  Korean water deer (Hydropotes inermis argyropus Heude, 1884): general outline for enlisting into the Red Data Book of Russian Federation. Biota and Environment of Natural Areas. (3): 35-40.

Cooke, A.S. 2019.  Muntjac and Water Deer: Natural History, Environmental Impact and Management. Pelagic Publishing. ISBN: 978-1784271909