Water Deer Food & Feeding - Species Eaten

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As discussed elsewhere, Chinese water deer are highly selective feeders, both in terms of the species they eat, and the parts of the plant they take. Given the option, they choose the tenderest (most easily digestible) growing tips and shoots, and their diet is broadly composed of graminoids—young, sweet grasses in particular, but also rushes and sedges—forbs (i.e., non-woody flowering plants), broad-leaved species, and occasionally conifers and woody browse. Grazing seems to account for more of the diet than browsing, at least here in Britain, and I'm told that when stalking them it is necessary to gralloch (disembowel) the carcass more quickly than for other species, owing to their preference for grazing making them “juicy”.

Full English

In the UK, where water deer are an introduced species, most of the dietary data in the literature come from studies on wild populations in Cambridgeshire by Arnold Cooke and Lynne Farrell, from free-ranging captive animals at Whipsnade Zoo by Stefan Stadler and Endi Zhang, and studies of a small number of animals held in private collections, such as those by Raymond Chaplin, Bob Lawrence, Michael Clark, and Rob Smith and his colleagues at Reading University.

An important point to begin with is that the species on which water deer are observed feeding on do not necessarily appear to be a good proxy for that species' prevalence in the diet. In their 1983 booklet, for example, Cooke and Farrell note how water deer are only rarely seen to browse on bramble, willow, hawthorn, and birch, yet rumen analysis from Woodwalton Fen in Cambridgeshire suggested that bramble was an important component of the diet, especially during the winter and spring. Indeed, the analysis, carried out by Lynne Farrell and Tony Mitchell-Jones, assessed the rumen contents of eight deer, six from Woodwalton, one from Holme Fen, and one from Monks Wood. Expressed as percentages of drained wet weight, at Woodwalton browse species made up one-third, the main components being bramble leaves (15%), buckthorn (Rhamnus cathartica) leaves and berries (6% and 3%, respectively), ivy leaves (3%) and sallow (Salix species) leaves (3%). The remaining 63% that could be identified were grazed species, nearly half (48%) of which were grasses and sedges. Nicely illustrating the variation seen in the diet of this species, the individual from Holme Fen had eaten mostly bramble (79%) and ferns (19%), while the Monks Wood animal had consumed only meadowsweet Filipendula ulmaria. In Muntjac and Water Deer, Cooke summed up this study:

“This small sample reflected the broad range of plant species that might be taken and showed how the ratio of the main dietary components could change from deer to deer and probably between days and seasons.”

Cooke and Farrell observed that water deer at Woodwalton also took the rhizomes of reeds and the shoots of chickweed, and Arnold tells me that they graze heavily on comfrey (Symphytum officinale), particularly during the autumn, and eat a lot of yellow iris (Iris pseudacorus) and water dock (Rumex hydrolapathum) leaf-tips in the spring. They may also tackle bullrush (Typha spp.) leaves, which is something mentioned to me both by Arnold and by Sharon Scott in Buckinghamshire. On the fen, Cooke and Farrell recorded that the deer grazed in peripheral farmland during the winter and spring, especially if there was snow or flooding in the reserve, but tended to lose interest in farmers' grass fields after the beginning of April, when the grass starts to seed. Growing shoots and buds have a higher protein content early in their season (i.e., during late winter and early spring) than once the growth finishes and leaves are functioning - come autumn, grasses are almost nutritionally worthless as resource is diverted to root growth. The grasses taken were mainly Timothy grass (Phleum pratense), cock's-foot (Dactylis glomerata) and velvet grass (Holcus lanatus), and most of the activity was within 300 metres (330 yds) of the reserve boundary.

Raymond Chaplin reported kale (Brassica oleracea var. sabellica) in the stomach of a water deer shot on farmland near Woburn, and while he doesn't give any specific details in either his private research notes or his 1977 book Deer, this does point to their seasonal opportunism. Similarly, water deer are well-known to take root vegetables in captivity, and Cooke and Farrell have recorded them feeding on carrot tops in farmland bordering Woodwalton during snowy winters. Furthermore, in early 1979, water deer at Woodwalton were observed feeding on potatoes left on the surface after harvest.

I have frequently observed water deer among cereal crops during the summer and on oilseed rape during the winter and early spring around Woburn, although they tend to feed on weeds in the fields and margins rather than the crops themselves. That said, Paul Childerley has reported issues with water deer damaging game cover and cereal crops in Bedfordshire. In Buckinghamshire, Sharon Scott tells me that the water deer typically spend the winter either on grass or cereal crops, particularly winter wheat, which are presumably quite attractive to them at that time of year, but we have no data on whether much damage is caused. Overall, we have little evidence of fruit in the diet of English water deer. Sharon has also told me, however, that she has seen water deer taking fallen crab apples (Malus sylvestris) during the late summer and autumn in Buckinghamshire, and I have one trailcam video that appears to show a buck eating them during December 2023. Endi Zhang noticed muntjac and wallabies eating crab apples at Whipsnade, but never observed water deer showing any interest. In December 2016, Michael Demidecki flushed a deer from an arable field while walking the Aylesbury Ring in Buckinghamshire and, upon investigating its couch (i.e., where it had been lying), found several sloe pips that had been, in his words, “ejected” by the deer. There is also one example I'm familiar with of water deer eating nuts. On 6th October 2024, wildlife photographer Steve Liptrot photographed a doe, in his words, “feasting on acorns in the middle of the day” at RSPB Strumpshaw Fen in Norfolk.

Much of the data on captive water deer diet from here in the UK comes from Whipsnade, and caution must be taken with their interpretation as rumen analysis of individuals there suggest the habitat is suboptimal for them and there are few, if any, suitable patches of sweet grasses and herbs. Certainly, Whipsnade's water deer tend to be more diminutive than those in the wilds of England and I've observed one eating dead oak leaves there during the winter, which might imply there is limited more desirable food available. This is despite the staff at the zoo providing deer pellets year-round and chaff during periods of snow and frost, which the deer largely seem to ignore. Nonetheless, Endi Zhang found two-thirds of the diet of deer at Whipsnade was grasses, 22% forbs and 4% woody species, with 8% of fragments unidentified. Overall, Zhang identified 19 species of monocotyledons (grasses, sedges, rushes, etc.), 13 forb and three woody plant species in the rumens of 11 deer surveyed between April and May 1994. Six species made up 40% of the grasses and these were, in order of abundance in the samples, common bent grass (Agrostis tenuis), meadow foxtail (Alopecurus pratensis), perennial rye grass (Lolium perenne), false broome (Brachypodium sylvaticum), red fescue (Restuca rubra), and cock's-foot. Stinging nettle (Urtica dioica) and mouse-ear hawkweed (Hieracium pilosella) were the most common forbs, accounting for 5.2% and 3.6%, respectively, while woody plant remains were from dog rose (Rosa canina, 3%), bramble (Rubus fruticosus, 0.6%), and hawthorn (Crataegus monogyna, 0.25%). Zhang also noted that the deer appeared to feed on thistles (Cirsium spp.), particularly during the winter when the plants turned yellow.

Outside of Whipsnade, Raymond Chaplin carried out palatability trials at the request of the Forestry Commission during the late 1960s. Japanese larch (Larix leptolepis), Norway spruce (Picea abies), Sitka spruce (P. sitchensis) and Douglas fir (Pseudotsuga menziesii) were offered to his captive animals. All stages and species had their lead (growing) shoots bitten out by the deer but browsing on peripheral branches was most severe on Larix and Pseudotsuga, while Picea were largely undamaged. Among his captive population at West Midlands Safari Park in the late 1970s, Bob Lawrence documented consumption of ragwort (Jacobaea vulgaris), bracken (Pteridium aquilinum) and foxgloves (Digitalis purpurea) without any apparent ill-effects.

Interestingly, it seems that despite readily taking fresh browse and grass in captivity, water deer refuse hay. In his 1950 opus, Kenneth Whitehead wrote of how, at Woburn during the hard winter of 1946/47, it was feared that the whole stock would die:

“They are greatly handicapped by their refusal to eat hay, and many, during this bitter spell, were found lying dead beside a haystack.”

Several authors and gamekeepers have also commented on how difficult it is to provide supportive feeding for water deer during the winter months.

In his engaging article to Country Life in May 1953, Whitehead described the early life of a water deer doe rescued as a fawn from Woburn Abbey after apparently having been abandoned and raised by hand. Whitehead noted that, once weaned, the deer's diet was quite broad:

“Her rations are now varied, ranging from carrots, porridge oats, and brown bread to anything she cares to help herself to in the garden. She is particularly fond of bindweed, as well as a nip here and there among the herbaceous border and rock plants.”

Along with a selective menu, it seems that water deer may supplement their diet with minerals, and the Bedfordshire Natural History Society records contain one report of a deer licking salt off a road in the county during mid-January 1988. Additionally, Whitehead described how the hand-reared doe was seen eating steamed fish put out for the owner's cat, and this remains the only report of flesh consumption of which I'm aware.

Asian aliment

To the best of my knowledge, we have no data on the diet of this species from its Russian or North Korean range, so all information on the food preferences of Hydropotes in its native range come from China and South Korea.

Robert Swinhoe doesn't appear to have made any reference (that I can find) to the diet of the water deer around Shanghai in his original papers describing the species. Indeed, the earliest formal study of their eating habits of which I'm aware was conducted during the late 1980s by Helin Sheng and S. Ou, who examined the winter diet of 136 water deer from the Zhoushan Islands in China's Zhejiang Province. The data, published in the mammalian ecology supplement of the Journal of the East China Normal University during 1990, show 34 species were identified from the rumen contents, 32 seed plants and two ferns, and suggest that the water deer here selected the leaves preferentially, rarely taking fruit (about 3% of rumen contents). A short time later, Lixing Sun analysed the rumen contents of deer from Poyang Lake Nature Reserve and, according to Endi Zhang in his Ph.D. thesis, found that 93% of the identifiable plant fragments were from herbs. Zhang goes on to note that short grass species including acanthaceous indigo (Strobilanthes cusia), cleavers (Galium aparine), and pale persicaria (Polygonum lapathifolium) are favoured by water deer in China.

In his thesis, Zhang describes how, in Yancheng, China, the water deer diet was found to comprise 23 species of grasses and sedges (23.5%), 58 species of forbs (59%), and seven woody plant species (17%), with the deer preferring forbs to either grasses or woody plants. Looking at the different parts of the plants eaten, about 46% were leaves, 23% stems, 15% buds, 8% flowers, and 8% fruits. Zhang gives the preferred grasses in Yancheng as red sprangletop (Leptochloa chinensis), sea-lavender (Limonium sinensis), Japanese bristlegrass (Setaria faberi), corn (Zea mays), creeping grass (Zoysia macrostachya) and eel grass (Vallisneria spiralis). Preferred forbs included soybean (Glycine max), alfalfa (Medicago sativa), Indian chrysanthemum (Chrysanthemum indicum), daisies (Ixeris sp.), false strawberry (now Potentilla indica), lawn marshpennywort (Hydrocotyle sibthorpioides) and fringed pink (Dianthus superbus). Woody plants taken included brush cherry (Syzygium buxifolium), cape jasmine (Gardenia jasminoides), chinaroot (Smilax china), shrubby bushclover (Lespedeza bicolor), common mulberry (Morus alba) and sea bilberry (Vaccinium bracteatum).

In their 1998 booklet Chinese Water Deer, Arnold Cooke and Lynne Farrell mention a study from China that found 96% of rumens contained sea bilberry, and a palatability study, also in China, where captive deer were presented with different types of food. Of the food taken, 59% of the species were herbs, 24% were grasses and sedges, and 17% woody species - again, mainly the leaves were eaten. Also in captivity, during their study of water deer vigilance at a wooded enclosure in Shanghai, published in the Chinese Journal of Zoology in 2012, Xin-Xin Tian and colleagues noted how the free-range animals were given supplemental food including bamboo (Banbusa multiplex), white clover (Trifolium repens) and peach (now Prunus persica).

Data collected at the Yancheng Nature Reserve suggested a predominance of forbs and grasses were taken, contributing 87% of the diet, but of the 48 species the deer were seen to eat, most were forbs and only 15% were grasses, despite them preferring habitat covered with graminoids. Studying the droppings of deer on the Zhoushan Archipelago, Guangpu Guo and Endi Zhang also found forbs (particularly legumes) and woody plants (especially ericaceous species) were dominant in the diet, with woody species taken most frequently during winter. At least 137 plant species, including 61 families and 115 genera, were taken by the deer. Herbaceous plants decreased while woody plants increased from spring to winter. The diet was dominated by forbs in spring (48%) and summer (50%), shifting to woody plants in the autumn (59%) and winter (61%), but both were the main components of the diet in all seasons. When looking at the plants on the study site that showed evidence of browsing, 60% were forbs, 30% woody species, 8% ferns and 2% grasses. Guo and Zhang's study, published in Acta Theriologica Sinica during 2005, and an earlier Chinese paper by Endi and Xiao-long Zhang at the Dafeng Milu Nature Reserve in Yancheng on China's east coast, published in the Sichuan Journal of Zoology during 2002, collectively reported that water deer also fed in agricultural/paddy fields, taking sweet potato, peas, wheat, and rape. Likewise, Helin Sheng and Houji Lu, in there 1984 Chinese paper to Acta Theriologica Sinica, mention Zhoushan deer sometimes entering farmland to eat bean sprouts, potato leaves and other crops.

Some of the earliest work on the diet of water deer in Korea with which I'm familiar was based on feeding signs, and during his Ph.D. studies at Chungbuk National University in the early 2000s, Bae Keun Lee found that water deer in the Woraksan National Park preferred Leguminosae (legumes), followed by Gramineae (grasses) and Asteraceae (daisies). In recent years, more focus has been turned on the diet of this species, possibly owing to its status as a pest in Korea, and in Mammals of Korea, published in 2018, Yeong-Seok Jo, John Baccus and John Koprowski summed up a diet that's broadly similar to that reported in the UK: plants taken from 15 taxonomic orders and a general preference for forbs and woody plants, with flowering plants and grasses the most significant components (in a ratio of around 60:30). Grasses are primarily taken in spring and autumn, legumes in summer and nightshades during winter.

Using genetic analysis of plant remains in 15 samples of water deer droppings collected in northern South Korea during July 2009, Baek Jun Kim and colleagues identified 18 orders and 24 families of plants. These were mostly from the Asteraceae family (28%), followed by Fagaceae (beech - 16%) and Polygonaceae (knotweeds - 11%). Overall, at the lowland site 94% of the plant remains were forbs, mostly Asteraceae followed by Polygonaceae. In the mountainous area, 30% of remains were forbs; here woody plants dominated (58% - mostly Fagaceae, then Rosaceae) followed by grasses (11%). Later, during a field survey of water deer in lowland Kangwon Province, the results of which were published in Landscape Ecology and Engineering during 2011, Kim and his team observed deer feeding on leaves of shrubs or arbores such as black locust (Robinia pseudoacacia) and willow (Salix koreensis), and more frequently on herbs on the ground under the trees.

Jihee Kim, Sungbae Joo and Sangkyu Park collected faecal pellets from the Janghang wetland in the Han River estuary between June 2013 and January 2015. Based on their DNA analysis of 77 samples, 35 genera of plants from 20 families were identified, with a prevalence of Salicaceae (27%), Fabaceae (17%), and Poaceae (14%). Forbs were taken most frequently (75% of samples), followed by woody plants (58%) and graminoids (23%), although woody plants predominated in winter (81%). In spring, 11 genera were detected (mostly Salix, Astragalus and Veronica), in summer 25 genera were taken (esp. Salix, Astragalus, Populus and Amorpha), and in autumn 21 genera and winter 11 genera were present (mostly Populus and Salix in both seasons).

More recently, in a paper to Scientific Reports during 2022, Seung-Kyung Lee and colleagues at the Seoul National University presented genetic data from water deer faecal pellets collected in South Korea suggesting browsing on woody plants was common in both summer and winter. A total of 40 samples were collected between April 2017 and March 2018, and the high-throughput sequencing identified 63 plant genera, with Morus (mulberry species) the most abundant. Interestingly, in contrast to an earlier paper by two of the same authors, which looked at the germination success of seeds in the faecal pellets and found many more (both in terms of number and diversity of species) forb seeds than graminoids or woody species, these data show woody plants dominated, accounting for nearly 70% of species identified, followed by forbs (7%) and graminoids (<1%). The most abundant genera were Morus, Rubus, Prunus, Corylus and Robinia. Unsurprisingly, deer in wooded areas ate more woody plants than those living in lowland areas, although season had a bigger impact on species taken than habitat. Morus, Prunus, Amorpha, Rhododendron and Hovenia were taken most frequently during the winter, while Rubus, Rosa and Corylus were more prevalent during summer. Overall, woody species constituted nearly 77% of the diet in winter and 60% in summer, leading the authors to conclude that Hydropotes is a browser by nature.

News articles from South Korea suggest these deer feed on soybean and peanut crops, which brings them into conflict with farmers. Several governmental documents also make mention of water deer damaging crops, although I know of no formal studies of their impact or damage assessments.

Overall, the diet of water deer across their range seems to be one of an intermediate feeder, browsing or grazing depending on the locally available plant species. Their diet composition is also likely to be influenced by humans where preferred crop species are grown and, writing in Zoological Research in February 2000, Endi Zhang suggested that water deer may be undergoing a change in diet and foraging, from woody plants and forbs in forests to forbs and grasses in grassland, as human activities force them out of forests into wetland grassland in their native Yangtze River range.

Finally, it is perhaps also interesting to note that water deer are rarely observed drinking. Presumably, subsisting on a diet of lush vegetation and dew supplies most of their water requirements.