Water Deer Reproduction - Suckling Behaviour

Drink up!

The suckling behaviour of water deer has been reasonably well described. Fawns are suckled roughly every four hours, meaning the dam returns five or six times over the course of a day – though Raymond Chaplin noted considerable variation between individuals: Pippa suckled her twins five or six times daily, while Becky nursed her single fawn far less often. Feeding intervals may be very long in some situations and, in their 2013 paper to China Animal Husbandry, Jun Gu and Guoya Gu note that fawns may be fed only once per day. Chaplin also observed that does may suckle a distressed fawn outside the normal schedule, adding occasional extra feeds.

During the first couple of suckling bouts, enzymes curdle the milk in the fawn's abomasum (true stomach), forming a dense, cheese-like mass known locally in China as naikuai (奶块, "milk lump") or zhangbao (獐宝, "deer treasure"). Curd formation of this kind is common among mammals, particularly ruminants. I know of no specific studies on the process in water deer, but in other ruminants the stomach secretes an enzyme called chymosin (sometimes also called rennin), whose sole biological purpose is to react with casein (the milk protein) and cause it to coagulate. Were the milk to stay liquid, it would pass through the fawn's still-developing digestive tract too quickly; by solidifying it into curd, the stomach can break it down slowly over several hours, ensuring maximum absorption of proteins, fats, and crucial immunoglobulins (see 'Milk matters' below). This slower digestion likely also works to the fawn's advantage in another way: by extending the interval before the next feed is needed, it reduces how often the doe must approach – a small but meaningful benefit while the fawn is still immobile and at its most vulnerable to predators.

Most observers agree that the peak suckling period lasts around three weeks, after which feeds become less frequent, usually tailing off entirely by seven or eight weeks. Chaplin's does were at either end of this range: Becky weaned her fawn at just four weeks, while Pippa continued nursing her twins for eight. By the standards of other British deer this is a short lactation. Suckling can, however, occasionally continue for longer, sometimes as late as 12 or 13 weeks. Steve Carter, for instance, photographed two almost-grown fawns suckling at Titchwell Marsh, Norfolk, in mid-September 2025. Roe (Capreolus capreolus), fallow (Dama dama), and red deer (Cervus elaphus), by contrast, often suckle their offspring sporadically well into October or November, at nearly six months of age. I have never observed or read of water deer attempting anything comparable, but would be glad to hear from anyone who has.

What prompts a doe to return to her hidden fawn to suckle is not fully understood. In her 1978 PhD thesis on the red deer of the Scottish island of Rum, Marion Hall suggested, however, the most likely trigger is the physical discomfort of a full udder:

"The mother's approach is possibly stimulated by a full udder, and if male calves do take more milk from her during each visit, so that it takes longer for her udder to become full again, this may explain the tendency for male calves to be visited less frequently than females."

It's an intriguing idea, and one that may well apply to water deer too. At Whipsnade, Endi Zhang observed that dams typically visited their fawns five or six times a day, each visit lasting a few minutes (two minutes on average) and combining suckling with grooming. He described two distinct patterns of initiation. In the first few days after birth, the dam would approach the fawn directly, sniff and lick it, and the fawn would rise to suckle. Once the fawn was a few days older, the doe would halt five to ten metres (16-33 ft) away and stand motionless, fixing her gaze on the spot where the fawn lay hidden; within seconds the fawn would rise and come to her, sometimes making nose-to-nose contact before nursing began. (As fawns grow older they become increasingly independent and find their own hiding spots, so the dam presumably returns only to the approximate area rather than knowing exactly where her fawn is.) I have only observed suckling by a very young fawn on one occasion, and in this case the doe simply grazed her way up to where the fawn was couched, rather than moving to it with the deliberateness Zhang described. The grass was tall enough to obscure the fawn almost entirely, so it was only the doe's posture and her standing motionless for a protracted period that alerted me to what was happening.

Zhang also noted that very young fawns appeared to suckle for as long as they wished, but that with older ones, does began terminating bouts themselves – raising their hindquarters and stepping sharply forward to break contact. At Branféré Zoological Park in southern Brittany, Christiane and Robert Mauget found that 63% of suckling bouts were initiated by the dam rather than the fawn.

Fawns appear to suckle from all four teats, though Chaplin observed that those in the groin were sought preferentially. This is interesting because in other species -- red deer and pigs, for example -- it is the anterior teats that produce the highest volume and most concentrated milk and are therefore most competed for, though no equivalent studies exist for water deer. In his PhD thesis, Zhang described how fawns may struggle to find teats at first:

"When very young, fawns searched for the teats at different parts of the dam's body, most often at the front legs, but when they were a few days old, they immediately rushed towards the inguinal region."

Water deer fawns also exhibit what is sometimes called a "food stroke" or Milchtritt ("milk step"). It's a behaviour recorded across several deer species in which the suckling fawn makes sharp, rhythmic upward kicks with one or both forelegs against the mother's flank or groin, apparently to stimulate milk flow. In a 2011 paper in Biological Bulletin Reviews, Vladimir Prikhod'ko and Elena Zvychainaya described the behaviour in musk deer (Moschus moschiferus) and noted its occurrence in water deer too – citing Hans Frädrich's 1966 paper in Zoologischer Garten, a reference I haven't been able to verify directly. Zhang's own thesis records that "the 'milk step', where fawns make rapid kicks with one front leg, was often observed", and Gérard Dubost and colleagues described the same behaviour as "blows of young with one foreleg to the female's hind leg". More recently, in a video to his social media channels in July 2026 in which he bottle-fed the two-month-old buck fawn he was hand-rearing, Paul Childerley received front leg kicks from the fawn on several occasions, including one before feeding started that appeared to suggest the fawn was anxious for feeding to commence.

Stefan Stadler, studying the same Whipsnade population as Zhang, noted the milk step alongside a rapid upward thrust of the head. This head-butting of the udder, or bunting, stimulates the release of oxytocin, a neuropeptide central to milk let-down, which both increases milk flow and strengthens the bond between the pair. In Stadler's observations, though, it seemed to cause the mother obvious discomfort, often prompting her to end the bout. I've never seen either kicking or bunting in wild fawns myself, but have only witnessed suckling on four occasions.

Nursing is occasionally done with the doe lying down -- more likely in the hours immediately after birth -- but both doe and fawn typically stand. The body position matters: in a 1998 paper in Acta Theriologica Sinica, Zhang described the characteristic posture required for successful nursing:

"Successful suckling seemed to depend on the dam and the fawn getting into the 'inverse parallel' position described [in] sheep. In this orientation, the fawn's muzzle pushed against the teat while dam stood firmly with her head turned back, nosing at the fawn's hindquarters. Her back was arched and her hind leg extended in a way which raised the teat and made it more prominent."

Suckling bouts are short and shorten further as fawns age. At Branféré Zoological Park in southern Brittany, Gérard Dubost and colleagues recorded a mean duration of around a minute and 35 seconds in the first week after birth, rising to just under two minutes at two to three weeks, then falling steadily to just over a minute at four to six weeks, and only 42 seconds by seven to nine weeks. At Whipsnade, vegetation often obscured the fawns, but Stadler managed to observe 74 suckling bouts averaging around a minute each (mean 57 seconds). In 43 cases where sex could be determined, females suckled for an average of 75 seconds and males for 55 – a difference that, while suggestive, was not statistically significant. The age-related decline seen at Branféré was mirrored at Whipsnade: bouts averaged 102 seconds in the first month, 40 seconds in the second, and 27 seconds in fawns older than two months. On the whole, male and female fawns appear to suckle for broadly similar durations, and while two fawns may nurse simultaneously, a doe with several young may equally feed each one in turn.

The shortening of suckling bouts with age likely reflects several overlapping factors. The initial need for a high nutrient intake to fuel this species' rapid early growth may demand longer bouts at first; Zhang observed that fawns at one to two days old suckled weakly and inefficiently, requiring extended feeding sessions before settling to around 43 seconds per bout by a week old. Hand-reared fawns collected from a reserve in China showed the same pattern: Hua Shen and colleagues reported in a 2007 paper in the Journal of Animal Husbandry and Veterinary Medicine that young fawns had little instinct to suckle and had to be force-fed, remaining poor sucklers until roughly a week of age – "eats less and spits out more", as the team memorably put it. As Chaplin noted in Deer, it is also worth bearing in mind that a fawn's stomach is not built to handle large volumes of fluid: the capacity is small, the milk is concentrated, and frequent short bouts suit the system better than long infrequent ones.

Stadler remarked that fawns younger than five days often looked visibly exhausted after nursing, which probably explained why they sometimes appeared to end bouts of their own accord. By two weeks, stronger and more robust, the dynamic had reversed: it was now almost invariably the mother who called time, most often simply by walking forward a step or two.

We know nothing about alloparental care -- also known as cooperative breeding, where a dam suckles or tends a fawn other than her own -- in wild water deer, and the species' broadly solitary nature suggests it may be uncommon. In captivity, however, where animals are kept at higher densities than they might naturally tolerate, it has been observed repeatedly. Peter Scherpe's 1971 thesis described an "aunt" figure in his captive study group who regularly groomed and suckled another female's fawn. At Whipsnade in August 1987, Stadler documented a male fawn nursing from an unfamiliar female who initially accepted him; after about 15 seconds she sniffed him, apparently registered the mistake, and moved sharply some 20 metres (66 ft) away to resume feeding. More typically, females responded to strange fawns with open aggression, kicking out at them with their forefeet; something I have observed both bucks and does do.

The most detailed picture of alloparental behaviour comes from Branféré Zoological Park in southern Brittany, where both Gérard Dubost and colleagues and Christiane and Robert Mauget documented it extensively. In their 2009 paper in Current Zoology, the Maugets reported that just over 10% of suckling bouts they recorded were non-filial. Females did not reject unrelated fawns outright if they were already caring for their own young, but invested significantly less in them: a female would groom her own fawn around 55 times on average, compared with roughly three times for an unrelated one, and rested with her own fawn for a cumulative total of around 86 minutes versus approximately three for a stranger's. Writing in Acta Theriologica in 2011, Dubost and colleagues noted that suckling and cleaning of unrelated young was common at Branféré, but never substituted for true maternal care – all fawns that lost their mother within the first eight days of life died, despite receiving allosuckling from other females.

More recently, Li Min's 2022 Master's thesis described similar patterns at Huaxia Park, where females occasionally groomed and suckled fawns that were not their own, though with markedly less investment: biological fawns were suckled 3.5 times more often and for 2.7 times longer than unrelated ones. One notable exception was a female who adopted an orphaned fawn after its mother died, nursing it more frequently and for longer than other dams nursed their own young. Cortisol analysis of droppings suggested that fawns receiving allosuckling were no more physiologically stressed than those nursing from their biological mothers – a finding that, given the disparity in care, is perhaps surprising.

Suckling is not always successful, particularly in very young fawns or when dam and fawn fail to align in the inverse-parallel configuration (head to tail) that appears necessary for standing nursing to proceed. Mothers sometimes reject attempts outright. One particularly well-documented example, observed by Endi Zhang at Whipsnade on the afternoon of 6th June 1993, illustrates the persistence this can demand: a male fawn made ten attempts to suckle over a 12-minute period while trailing his dam, all of which she rejected, though she did pause to groom him. Thirty minutes later he tried again -- 18 more attempts -- before finally being allowed to nurse for 37 seconds. I have observed suckling by fawns a week or so old on a handful of occasions, and in all cases the fawn made several failed attempts to suckle before succeeding the third or fourth time. Failed attempts occurred because the female broke contact in the manner described by Zhang: stepping forward or, on one occasion when the fawn attempted to suckle from the side rather than from behind, stepping over the fawn.

Milk matters

Data on Chinese water deer milk are sparse. The Animal Diversity Web states that the milk is high in protein and antibody content, though without citing a source. Chaplin describes it as "rich and nourishing, with the first few feeds being predominantly colostrum", which is consistent with what we know of ungulate physiology more broadly. Because the epitheliochorial placenta of ungulates blocks the transfer of immunoglobulins -- the large protein molecules central to antibody production -- fawns are born in a hypo- or agammaglobulinaemic state. In other words, they're born with few or no circulating immune proteins, and must take in colostrum rapidly after birth to acquire passive immunity.

Yong Xia and colleagues, writing in Modern Preventative Medicine in 2008, found that water deer colostrum is around 39% protein and contains 17 amino acids, seven of them essential. Inorganic analysis revealed a calcium content of almost 960 mg per 100 g of dry powder, alongside copper, manganese, zinc, and other trace minerals. In his 2013 patent application, Liang Zheng notes that nutrient levels in this colostrum curd are higher than regular dairy products, with exceptionally high concentrations of glutamic acid, proline, valine, and lysine, and that the immunoglobulin content is high – up to 28.5%. Once curdled in the fawn's stomach, this colostrum is known locally in China as zhangbao, highly prized as a folk medicine and showing some promise in treating infant anorexia in clinical trials. Water deer are now farmed in China specifically for this product.

Chaplin analysed a small post-colostrum milk sample and found it contained 18.4% total solids, 6% fat, 8% protein, and no lactose – a notably different composition from both cow's milk (approximately 3.6% fat, 3.3% protein, 4.1% lactose) and human breast milk (3.5% fat, 1.5% protein, 7% lactose). In some deer, red deer among them, milk composition shifts across the lactation period; whether this is true of water deer is unknown.

Zhipeng Li and colleagues analysed the milk of eight does kept on a farm in Yancheng, China, for bacterial content, and found a notably high microbial diversity – higher than that recorded in reindeer. The dominant genera were Pseudomonas spp. and Acinetobacter spp. (each around 12% of genera present), with smaller contributions from Chryseobacterium spp. and Corynebacterium spp. (each around 5%) and Comamonas spp. (4%). At the phylum level, Proteobacteria dominated (60%), followed by Actinobacteria (15%) and Bacteroidetes (14%). The stress of labour is known to increase gut permeability in many mammals, allowing bacteria to translocate from the gut into the milk; writing in Scientific Reports in 2017, Li and colleagues suggest that the demands of water deer's characteristically large litters may intensify this stress response, resulting in greater permeability and a correspondingly richer milk microbiome.

This rich milk fuels rapid early growth. At Whipsnade, James Kirkwood and colleagues tagged and weighed 79 mother-reared fawns living free-range in the park, finding that growth followed a roughly linear trajectory across the first month: fawns began at around one kilogram and reached almost three kilos (6 lb 9 oz.) by 30 days, gaining an average of 70 grams per day. Hand-reared fawns in the same study gained 50-70 grams (1.7-2.5 oz.) per day, falling to around 40 g (1.4 oz.) per day after weaning. In a 1990 paper in the Journal of East China Normal University (Mammalian Ecology Supplement), Li-xing Sun and Helin Sheng reported that fawns in Shanghai gained 90-106 g per day (3-4 oz.) consistently across their first month, reaching around 12 kg (26 lb 6 oz.) by six months of age. Taken together, these figures suggest fawns can add between 50 and 100 grams (up to 3.5 oz.) daily in the first month or so, and have reached roughly 80% of adult body weight by six months – a growth trajectory that, even by the standards of small deer, is impressively fast.

References

Chaplin, R.E. (1977). Deer. Blandford Press, Dorset.

Dubost, G. et al. (2011b). Social organization in the Chinese water deer, Hydropotes inermis. Acta Theriologica. 56: 189-198.

Frädrich, (1966). Einige Verhaltensbeobachtungen am Moschustier (Moschus moschiferus L.). Zoologischer Garten. 33(1/3): 65-78. [In German]

Gu, J. & Gu, G. (2013). Techniques for raising river deer. China Animal Husbandry. (20): 82-83. [In Chinese]

Hall, M. J. (1978). Mother-offspring relationships in red deer (Cervus elaphus L.) and the social organisation of an enclosed group. Ph.D. Thesis for University of Sussex.

Kirkwood, J.K. et al. (1988). Management and formula intake of young hand-reared Chinese water deer. International Zoo Yearbook. 27: 308-316.

Li, Z. et al. (2017). Unique bacterial community composition and co-occurrence in the milk of different ruminants. Scientific Reports. 7: 40950.

Mauget, C. & Mauget, R. (2009). Maternal investment and reproductive success in Chinese water deer. Current Zoology. 55(2): 102-110.

Min, L. (2022). A study on cooperative parenting behaviour in captive female water deer (Hydropotes inermis). M.Sc. Thesis for East China Normal University. [In Chinese]

Prikhod'ko, V.I. & Zvychainaya, E.Y. (2011). Behavior and phylogenetic relations among Artiodactyla families (Artiodactyla, Mammalia). Biological Bulletin Reviews. 1(4): 345-357.

Shen, H. et al. (2007). A preliminary study on artificial breeding of river muntjac. Journal of Animal Husbandry and Veterinary Medicine. 26(6): 65-66. [In Chinese]

Stadler, S.G. (1991). Behaviour and Social Organisation of Chinese Water Deer (Hydropotes inermis) under Semi-natural Conditions. Ph.D. Thesis for Universitat Bielefeld, Germany.

Sun, L. & Sheng, H. (1990). Chinese water deer at the area of Poyang Lake. Journal of East China Normal University (Mammalian Ecology Supplement). September (1990): 21-26. [In Chinese]

Xia, Y. et al. (2008). Experimental study on the effect of Chinese water deer gastric lumpy content on the growth and development in rats. Modern Preventative Medicine. 35(19): 3708-3710. [In Chinese]

Zhang, E. (1996). Behavioural ecology of the Chinese water deer at Whipsnade Wild Animal Park, England. Ph.D. Thesis for University of Cambridge. 196 pp.

Zhang, E. (1998). Uniparental female care in the Chinese water deer at Whipsnade Wild Animal Park, England. Acta Theriologica Sinica. 18(3): 173-183.

Zheng, L. (2013). Use of Zhangbao in the Preparation of Medicines for Preventing and Treating Gastric Cancer and Its Precancerous Lesions. Grant Publication: CN103251650B. [In Chinese]