Water Deer Interaction with Humans - Agricultural & Conservation Interests
Water deer are arguably our least-studied deer species, with many gaps in our understanding of their biology and behaviour, and this extends into a recognition of the impact on farming, forestry, and conservation interests. Populations have increased significantly in the past few decades, both here and, it seems, in parts of their Korean range, and this likely means their impact is greater now, too, although data are generally lacking. As Arnold Cooke put it in his 2019 book Muntjac and Water Deer, though, water deer must eat, and their biomass is such that the potential exists for them to cause impacts on native flora and fauna. Part of the problem with getting a handle on this subject is that water deer don’t exist in isolation; they coexist with other deer species that may feed in very similar ways on similar species. Consequently, it can be difficult, sometimes impossible, to separate damage caused by one species from that caused by another without the kind of robust monitoring that only currently exists for a handful of sites. The following is a summary of the data of which I am aware on water deer impacts, and I would be extremely interested to hear from others with experience of the topic.
British bother?
In common with all wild deer species in Britain, the water deer population appears both to be increasing and spreading, albeit more slowly than some other introduced species, and with this comes potential conflict with landowners. Water deer are known to feed on crops, including carrots, sweet potatoes, soybeans, bean sprouts and cereals (see: Food and feeding behaviour) although, again, the damage they cause seems less than that inflicted by other deer.
I posted a question regarding water deer damage to a well-populated deer stalking Facebook group in 2020. The consensus was that, in England, they do little, if any, damage in woodland, and are likely to be only a minor pest in cereal crops under most circumstances. I've had similar feedback from estate managers and farmers. One stalker who responded to the Facebook post noted that he watched the same deer repeatedly feeding on spring growth maize early in the season, while another described some damage to maize crops on his beat and what he referred to as a "decimation" of the oilseed rape crop, although this was in combination with a very wet autumn that put additional pressure on the crop. Overall, the situation was summed up by one respondent:
"On our shoot you can definitely notice a bit of grazing along the edge of some areas of wood that hold more deer. Nothing that bad normally to be concerned about yield.
Arnold Cooke, in Muntjac and Water Deer, recounted that Callum Thomson, when he was Woburn Estate deer manager, received reports of some unspecified crop damage at nearby Potsgrove, which at the time held a deer population of eight or nine per sq. km. At the Claxton Estate in Norwich, where the water deer population was approaching 25 per sq. km in 2016, there was no concern about damage to crops, the deer doing no more damage than hares and significantly less than rabbits. Having spoken recently (January 2024) with Claxton's manager, John Heathcote, about this, it appears that the situation has not changed despite the population having increased. In episode 17 of his Deer Management with Chris Rogers series, aired on the Shooting & Country TV YouTube channel during mid-December 2022, however, Rogers mentioned that water deer can cause grazing damage on agricultural crops if densities increase, as well as causing disturbance during gamebird shoot days, and often becoming trapped in fencing.
In his 2009 International Urban Ecology Review paper on this species in Britain, Cooke noted that water deer were feeding on the newly-sown farm grassland at Woodwalton Fen during the spring of 2009, and while this was of no consequence in the Great Fen conservation project, it could've been important had the intention been to graze the fields commercially with livestock. At the time, Cooke assessed the feeding impact of water deer on the reserve to be "intermediate stage", showing slight impact. The only indicator that provided any grounds for concern was the damage to the readily palatable comfrey (Symphytum officinale) during the autumn, 35% of sample plots showing evidence of grazing, and Cooke noted:
"Although grazing on comfrey itself is not an issue for the reserve’s managers, it could indicate that nationally rarer, but locally common, species might potentially be at risk."
While general browsing damage might be low, there are circumstances where water deer may have a more significant impact, such as impairing or preventing regrowth of sallow (Salix caprea) coppice. In 2010, for example, browsing was considered the reason three of 15 coppiced sallow plots in the north of the Woodwalton Fen reserve had unacceptably poor growth. Many more water deer than Reeves' muntjac (Muntiacus reevesi) were sighted in the area, suggesting they were causing most of the browsing damage here. In a related study on the reserve, while water deer all but ignored ivy bushes, they accounted for almost 61% of the browsing videos on young sallow coppice regrowth, muntjac in the remaining 39%.
In the spring of 2014, Arnold Cooke undertook a small trial to test whether impact on regrowth might still be occurring at the fen. A small patch of sallow was selected in an area with a high density of water deer and, in May, leafing stems of sallow were cut in a patch a few metres across. Stems were cut at about 40 cm (16 inches) above ground, surrounding vegetation cut and flattened, and remote cameras installed. The trailcam footage during June and July suggested water deer were more active in the area than muntjac and were responsible for 92% of the browsing. The level of browsing was judged to be unacceptable, with no regrowth above a metre (3.3 ft.), and while several water deer were identified in the videos, a buck with a distinctive broken tusk was responsible for most of it (i.e., 74%), indicating some may be "problem" individuals for sallow regrowth. In his 2012 report to Nature of Cambridgeshire, Cooke described how the deer's grazing in the reserve altered the vegetation structure:
"The impact of the brief, but fairly frequent, episodes of browsing on the willow was often to create and maintain ‘micro-lawns’ of densely-packed new growth a few centimetres in height and perhaps 10 or more centimetres [4 in.] across. From a distance these resembled patches of moss. These fast growing young stems seemed very palatable to the deer."
Outside of the reserve, deer were observed taking carrot (Daucus carota) and sugar beet (Beta vulgaris var. saccharifera) crops, both in the ground and in storage, particularly when forced onto farmland by flooding or snow, or in periods of high density. The damage was very limited, nonetheless, as the deer tended to focus on the green tops rather than the root, unless they'd been earthed over, and didn't aggregate. Water deer apparently also knocked ears off barley when running through the crops just prior to harvest, but Cooke reported that, overall, the farmer was unconcerned about the minimal losses in yield. Similarly, up until 1968, the 68-hectare (170 acre) farm at Whipsnade Zoo grew food for the collection, including barley, oats, wheat, potatoes, kale, and Russian comfrey (Symphytum x uplandicum). In their 1988 paper to the Journal of Zoology, Reinhold Hofmann and his colleagues note that, although water deer were recorded in the farm area throughout the crop-rearing period, no significant damage to crops was recorded. Writing in the Norfolk Bird and Mammal Report for 2000, David Nobbs, the then-warden at Wheatfen reserve in the Yare river valley just south of Norwich, described water deer as making "an attractive addition to the fauna of Wheatfen and cause little damage on the reserve".
More recently, on the Beckerings Estate in Bedfordshire, Paul Childerley explained that the deer can have an adverse effect on commercial flower crops by feeding on the flower heads, but typically do little damage provided the numbers are maintained at a reasonable level. Childerley told me that a significant number had to be culled on the estate in the 2020/2021 winter, as they were causing "some considerable damage" to the game crop. Beckerings drill maize and sorghum (Sorghum bicolor) as a game crop, and oilseed rape is widely grown on the tenant farms. Conversely, John Heathcote, owner of the Claxton Estate in Norfolk, told me in December 2024 that they see few, if any, impacts from water deer either on their marshland or arable crops, and the deer were much more likely to be found feeding on "weeds" among the crops or in set-aside than eating the crops themselves. Around the same time, David Hooton, the Forestry Commission East and East Anglia Deer Manager, noted that the Commission were getting more reports and evidence of water deer impacts in woodland and on crops where densities are high, including deer impacting set-aside buffer strips planted for birds and butterflies:
"We have seen significant populations of [water deer] developing in East England over the last 10 years, based on the fact that there was thought to be little impacts from them. Having met a few owners in the Norfolk Broads recently we are seeing subtle changes in composition of floral interests in grazing marshes, and also impacts to reed beds, attributed to [water deer] and red deer, often difficult to tell the differing impacts apart in reed beds. Reed cutters are reporting significantly less growth on reeds than a few years ago, this has coincided with the increases in both [water deer] and red deer."
In March 2025, a deer stalker based in Suffolk told me that he's seen significant increases in water deer on the grounds in Norfolk, Suffolk, and Cambridgeshire on which he works, and that farmers are seeing damage where densities are high, such as on the Norfolk Broads. He explained that, as these deer don't move around much, they're in fields virtually 24 hours per day all year and, while the winter crop can benefit from grazing, he has observed them suppressing rye crops. Perhaps more significantly, the deer lie out on top of the winter barley, flattening the crop and increasing the combining costs for the farmer. Furthermore, the deer defaecate in their couches on the crop and the combine sieves cannot differentiate between the cereal heads and deer droppings, resulting in batches being rejected.
While the situation may be slowly starting to change, despite many nature reserves in East Anglia and the Home Counties being home to (sometimes substantial populations of) water deer, it seems that few consider the damage significant enough to warrant culling. In their report on fenland ecosystem services, published in 2011, for example, Centre for Ecology and Hydrology ecologists Jerry Tallowin, Owen Mountford, and Joanna Savage wrote:
"The Chinese Water-deer (Hydropotes inermis) is locally frequent in wetlands in eastern England, but there is no suggestion that their grazing is having an unduly damaging impact on swamp communities."
Similarly, in September 2024, Suffolk Wildlife Trust Deer Manager Matt Gooch told me that, while there are significant populations of water deer across their sites, including more than 100 animals on the 486 ha (1,200 acre) Carlton Marshes reserve near Lowestoft, observational surveys of the reserves in the north east of the county showed no discernible impact from them. Consequently, the Trust doesn't manage water deer on any of their reserves, although Matt noted that this decision would be reviewed in the event that damage was reported, or if local land owners struggle to manage the deer on their land. With that in mind, David Hooton mentioned to me one landowner near Lowestoft who believes that an increase in water deer on his grazing marshes has resulted in fewer flowering plants. Further west, in Bedfordshire, Senior Ranger at the Forest of Marston Vale Nicola Ceconi told me, in June 2024, that the reserve does not currently either survey the water deer population or carry out any culling, although this is a subject that's under frequent review, adding:
"Generally speaking, we do find that the Chinese water deer do less damage than the muntjac, but we are seeing more of them in recent years and they are definitely browsing the hedgerows in the wetlands."
In Muntjac and Water Deer, Arnold Cooke recounted discussions with Tim Strudwick, the RSPB warden at Strumpshaw Fen in Norfolk, who had not noticed any problems from water deer grazing or browsing in 2010, despite the local summer density on the reserve being about 20 per sq-km. The only issue raised was whether their paths through the reed beds allowed foxes easier access to predate nests of rare birds, but he explained in 2016 that this concern had not been realised. Indeed, if deer paths through the reeds benefit fox ingress, this could equally promote higher fawn mortality, given that foxes may be a significant predator of fawns.
At the time of writing, I'm aware of only one nature reserve on which water deer have been recorded as causing significant damage. Orford Ness is a coastal shingle spit in Suffolk owned and managed by The National Trust that covers about 888 ha (2,194 acres) and, in his note to Essex Naturalist in 2022 on the spread of the species in the county, John Dobson referenced a conversation with the late naturalist Steve Piotrowski in which Piotrowski mentioned they were causing a lot of damage to the SSSI at Orford Ness, eating the rare lichens in winter. In an email conversation during January 2025, Area Manager Sam Cooper explained that a cull had become necessary after the water deer population on the reserve had risen to the point where they were damaging the crust of the shingle, which can take a decade or more to recover, and were also disturbing the wetland grazing marshes where a variety of ground-nesting birds nest, causing nests to be abandoned and leaving eggs and young birds vulnerable to predators. Sam noted that vegetated shingle in the form Orford has is both extremely rare and extremely fragile; deer damage it by trampling the crust, destroying the stone layout crucial for moisture to be trapped and plants to grow, causing a long lasting (sometimes permanent) impact. In addition to the number of deer running across the lichen heaths on the shingle breaking it up and damaging its structure, the animals were also grazing the ground flora, causing significant pressure on both the lichens heaths and general vegetated shingle plants (i.e., sea campion, Silene uniflora, and sea beet, Beta vulgaris subsp. maritima). Sam added that he believed that there was likely also some trampling of eggs by the deer, although no direct evidence has been recorded from the reserve.
In their extensive report on deer impacts in the Norfolk Broads, published in February 2025, the Broads Authority note that, based on thermal drone surveys, water deer are clearly the most abundant species, especially in the fens and marshes in the southern catchments where densities may exceed one per hectare, above the densities reported to trigger damage. Increased numbers of red (Cervus elaphus) and water deer moving through the reeds appears to be causing damage, reducing reed height, dominance, and flowering, reducing overall abundance and impacting habitat specialists such as bitterns (Botaurus stellaris), which have declined in the National Park in recent years. Increased browsing damage has also been reported, including of milk parsley (Peucedanum palustre), which is a vital food plant for caterpillars of the endangered swallow-tail butterfly (Papilio machaon). Further surveillance work is underway to better understand these impacts and relationships.
In their assessment of the impact of 34 alien mammal species introduced Europe published in 2010, University of Bern researchers, led by Sven Bacher, assigned water deer a "total impact" score of five. This score was the combination of a "potential impact" of two for environmental and three for economic damage. The "actual impact score" was 0.01 and 0.014, for environmental and economic, respectively. For context, Reeves' muntjac and fallow (Dama dama) were given a total impact score of 25. Hence, the analysis considered water deer to have a low socio-economic impact, the species displaying a low potential impact and a highly restricted distribution in England. Similarly, in 2011, Sabrina Kumschick and colleagues published their analysis of the "invasiveness strength" of a variety of mammals and birds. They assessed multiple factors and used them to calculate an impact difference score; the higher the score, the more invasive the species was. Water deer were given an average economic score of -0.7 and an average overall score of -0.2, suggesting that they're weak invaders. Again, for context, the Reeves' muntjac scored 2.3 and 2.5, respectively. Water deer certainly appear less exploratory than muntjac, which may contribute to them being weaker invaders, but numbers can build quickly in colonised areas.
In 1996, Alan McCormick and Jamie Cordery canvassed 10,000 BASC members in the UK to survey their deer stalking activity over that year. Based on just over 6,700 responses, it emerged that water deer represented only about 0.2% of the animals culled that year, versus 49% roe and 24% red deer. I know of no more recent data for Britain at the time of writing, although speaking with stalkers and the Forestry Commission, it is fair to say that significantly more water deer are taken in cull plans today than in 1996. There is currently a project underway by the Forestry Commission that may provide new insight in both the distribution of culling effort and number of deer killed in the coming months.
Native nuisance?
Robert Swinhoe, in his original 1870 description of the species, noted that the deer ate mostly rush sprouts and coarse grasses but "they doubtless often finish off with a dessert from the sweet-potatoes, cabbages, &c. which the villagers cultivate on the islands during the winter". He nonetheless points out that the fact the deer are permitted to persist in such abundance suggests that they do very little damage to crops. Writing in Shooting in China, published during 1908, however, US consul in Kobe Thomas Jernigan recounted the experience of Jersey-born adventurer and writer Major-General William Mesny during his first campaign in Kwei-chow (modern day Guizhou, a mountainous province in southwest China), between 1867 and 1874. Mesny had described to him by natives a large and ferocious animal referred to locally as Ma-hswing ("house bear"). (I think this might've been a phonetic misspelling of Jiā xióng, 家熊.) It was larger than the biggest bear, with a mane like a horse, brown as an ox and ferocious as a panther; its roar was heard miles away. The farmers were well disposed to the Ma-hswing, though, because it kept away predators that took livestock and its favourite food was the deer and wild pig, two of the greatest and most persistent depredators known to the farmer. This suggests that farmers were in well-established competition with deer by the mid-19th century, and Jernigan goes on to say "... there can be no shadow of doubt that [river] deer play havoc with the grain crops ...".
We know little about the present impact of water deer on agriculture in China, although the drastic reduction in the species' range and population in recent years likely means damage is concomitantly lower than when Swinhoe and Jernigan were travelling. In his thesis on water deer ecology at Whipsnade, Endi Zhang notes that in China they're fond of crops including soybean, peanuts, and sweet potatoes. Additionally, in their Chinese paper to the Sichuan Journal of Zoology in 2002, Endi and Xiao-long Zhang report the results of a survey of local people living and working around the Defang Milu Reserve in Jiangsu Province during February and March of the previous year. The results indicate that water deer commute through cotton fields at night en route to forage in wheat and rape fields when food is limited in the winter, suggesting potential conflict with farmers.
In Korea, the picture seems very different and, in the south at least, Korean water deer have been designated a "harmful wild animal" since 1994, owing to the damage they inflict on crops and the number of traffic accidents they cause. In their 2018 Mammals of Korea, Yeong-Seok Jo, John Baccus and John Koprowski state that some 11,000 deer are eradicated as vermin each year in the South, and that the meat has little, if any, economic value, which aligns with discussions I've had with Korean naturalist Junha Kim. Jihyang Jung and colleagues, in their 2016 paper to Animal Cells and Systems, suggest that the agricultural sector in the South want the government to take action to manage water deer numbers:
"Farmers have been appealing to the [Korean] government for actions to reduce the deer population; however, the government has not yet responded …"
In a paper to the Korean Journal of Environmental Biology published during 2007, Seong-il Yoon at Hanyang University in Seoul presented the results of crop loss survey by wildlife in 11 of South Korea's national parks. The data, which took the form of interviews of farmers, suggest damage by deer both in terms of trampling the crop and eating tender leaves of cabbages, sweet potato, and beans. Indeed, while the survey data do not differentiate damage caused by water deer from that by roe (Capreolus capreolus), it does suggest that the two species caused significant damage to cabbage and bean crops in particular.
More recently, Eun-kyung Ko's article to The Hankook Ilbo newspaper (a well-respected newspaper in Seoul), published in November 2023, reported that between 150,000 and 200,000 water deer were killed each year under a government bounty scheme because they damage crops. The article quotes statistics released by the Ministry of the Environment, who run the bounty scheme, which suggest that, in 2022, just over 153 thousand water deer were shot having been estimated to cause nearly 1.2 billion won's-worth (£640,000 / US$822,000 / €750,000) of damage to crops, although this is down from a peak of just over 3 bn ₩ (£1.6 m / US$2 m / €1.9 m) in 2012, when only 30,000 deer were shot under the bounty scheme. In 2018, according to the article, one water deer was shot because it was suspected of having eaten about 15,000 ₩ (£8 / US$10 / €9) worth of crops, about half the bounty price per animal.
Ko, The Hankook Ilbo's animal welfare reporter, explains that a contentious element of deer management in South Korea is that while hunters are paid per deer shot, farmers who suffer losses tend not to be compensated because the critical threshold for reimbursement is 100,000 ₩ (£53 / US$69 / €63) is difficult to demonstrate because water deer damage tends to be small scale but repetitive. The article goes on to point out that water deer are a resource worthy of protection in South Korea and more effort should be directed to keeping deer off important crops, either by installing fences or planting species that the deer prefer elsewhere on the farms to distract them from the main crops, and where this isn't possible government funds should be used to compensate farmers appropriately rather than on bounties. The public comments left against the article are mostly people agreeing that water deer are a problem for farmers but criticising the author for underestimating the level of damage they inflict, with several mentioning that the deer trampling/flattening crops is just as important as feeding damage.
We know little about the population or its impacts in the North, but Jo, Baccus and Koprowski mention that the Gwangju Metropolitan government designated this species a “Provincially Protected Species” in 2011 owing to conservation concerns:
"The North Korean government made a habitat for the species at Mt. Guwol, Hwanghaenam Province a Natural Monument. Despite several releases of Chinese water deer by North Korean government, populations remain small due to illegal snaring for bush meat."
Researchers I have spoken with similarly consider it probable that the North's population has declined significantly in recent years.
At the time of writing, however, I know of no current data on the financial cost of water deer to agriculture anywhere in the world, nor on how many water deer are culled globally each year to protect crops.