Water Deer Reproduction - Male Aggression

A pair of majestic red stags or fallow bucks, antlers locked, engaged in a muscle-rippling bout of virility, is perhaps the quintessential image of the deer rut. Despite their more diminutive stature, however, the rut of the water deer is potentially no less energetic or dangerous, although as with all deer species combat appears to be a last resort.

Combat between water deer bucks is rarely observed, much taking place in cover and under the cover of darkness. - Credit: David Ziggy Greene

Kenneth Whitehead in 1950, Centre d'Écologie générale de Brunoy naturalist Francois Feer in 1982, and most recently Gérard Dubost in 2011, all remarked that parallel walking is part of the territorial defence behaviour of bucks. Dubost and his colleagues described this as a stiff-legged walk. Whitehead also noted that ground-scraping with a foreleg and urination may accompany this parallel walk, which corresponds with my observations in Bedfordshire and Norfolk. Additionally, I have observed that the bucks may not always walk in parallel, periodically separating and one walking ahead of the other. Feer suggested that this walking behaviour is the only prelude to chasing and/or fighting, and that there doesn't appear to be any specific canine display as is seen in musk deer, although German naturalists Detlev Müller-Using and Robert Schloeth appear to hint at a 'canine threat' in their chapter on deer behaviour in Handbuch der Zoologie, published in 1963. Stefan Stadler never observed such a threat in his study group at Whipsnade, and I have never seen it nor come across any other descriptions in the literature.

In their 2008 chapter on water deer in Mammals of the British Isles: Handbook, 4th Edition, Arnold Cooke and Lynne Farrell explain how bucks approach one another with a stiff-legged gait, heads held low (i.e., necks below horizontal, in an aspect Fritz Walther called 'Kopf-tief-Halten' or 'Kopf-tief-Drohen'; basically “head down threats”) and rotated in such a way as to cause “ear-slapping”. In their 2009 book Wild Deer in Britain, Roy Harris and Ken Duff note that territorial chases are sometimes preceded by the territory holder approaching the intruder with neck stretched out down to the ground and head rotating, causing “his ears to flap rather absurdly, but presumably at the same time the tusks are displayed to their best advantage”. So, the ear-slapping may not be an activity in its own right, but perhaps collateral in an attempt to show off the tusks, although I have observed tuskless deer perform this behaviour. During the approach, the hackles, a roughly egg-shaped patch of fur on the shoulders, may be raised, and this has been described both by Stadler at Whipsnade and Sharon Scott in Buckinghamshire.

The risk of (potentially serious) injury means that fighting is a last resort for bucks and they employ a suite of body language to prevent things escalating, which includes, parallel walking, ear-slapping and mouthing. Here, two bucks in Norfolk face-off and exhibiting ear-slapping, mouthing and, during the brief chase, scissor-kicking. - Credit: Marc Baldwin

At Whipsnade, Stadler observed that in most cases an aggressive approach never escalated, with the approach of one animal leading to the withdrawal of the other in 73% of cases. In Norfolk, I have observed a smaller buck ear-slap and mouth towards a slightly larger one that appeared to be dominant (based on scent marking and chases observed earlier) but which made no obvious response, before moving away; the dominant buck followed and gave a brief chase of the subordinate, which fled.

If the bucks get close, they may walk in parallel some 10-20 metres (33-66 ft.) apart, with tail held out horizontally, before one chases the other if neither back down. In my experience, parallel walking may be accompanied by “mouthing” (i.e., a rapid opening and closing of the mouth), which I believe is the same as the “tongue flicking in vacuum” that Dubost and his colleagues mention briefly in their 2011 Acta Theriologica paper, and the “self-licking”, which involved the tongue appearing alternatingly on both sides of the mouth at an interval of 0.5 to one second and sometimes exaggerated chewing movements, Stadler noted in his thesis. Stadler suggests that while the origin of the behaviour may lie in aggression, this self-licking may be a self-reassuring behaviour associated with a highly excited state. At Whipsnade, Stadler noted that parallel walks normally lasted only a few seconds, but in some cases went on for several minutes, and I've seen males continue for 30 metres or more, even through quite dense vegetation where either is obscured from the other. Long and intense walks in Stadler's population were often interspersed with feeding bouts (i.e., walk, feed, walk, feed), which might form the same function as the “agonistic grazing” seen in herbivores such as wildebeest. Sometimes a walk intensified further into a “parallel run” that continued for up to 100 metres. Stadler observed:

When, for at least one of the contestants, the distance to the centre of his territory became too large, he turned round and moved back, and this change of direction was usually matched by the opponent.

Two water deer bucks in Norfolk engage in parallel walking, along with some mouthing, ground-pawing and "agonistic grazing". - Credit: Marc Baldwin

Defaecation and ground-pawing by both individuals during parallel walking contests was observed by Stadler and is something I have also witnessed on several occasions. Freie Universität Berlin behaviourist Wolf-Peter Scherpe mentioned a “Drohstampfen”, or 'threatening stomp' of the forefeet carried out by a buck towards another, although I know of no other reports. In their 1983 booklet on water deer, Arnold Cooke and Lynne Farrell note that confrontation displays may also include a buck stretching out his neck and shaking his head from side to side. The authors describe having occasionally “been threatened by bucks in this manner”.

A pursuing buck may emit a call variously referred to as “whickering, “chirruping” or “chittering” (see Vocalisation) during the chase or fight and/or immediately upon victory (see 'snow fight' video below), while retreating animals almost never appear to vocalise. Aggressors may attempt to “scissor kick” the fleeing animal with both front legs simultaneously. Spoored bucks typically manage to evade their pursuer either in cover or by having moved sufficiently far from the dominant animal's territory and chases tend to be relatively short, although I have seen determined bucks pursue others for several hundred metres at considerable speed. Raymond Chaplin has observed that strangers accidentally straying into a territory are chased only as far as the boundary by the master buck, while those having challenged for the territory may be chased several hundred yards out of the territory before the pursuit ends and the territory holder returns.

If neither buck backs down, or a pursued animal finds courage, things can escalate. In some cases, the bucks will face one another weaving and bobbing their heads while making “pouncing” movements to either side. As with the initial approach and parallel walk, the bucks may separate after this without physical contact. Alternatively, a fight may ensue. Where fights do break out, they invariably appear to be the result of a challenge for territory.

Chases can be short or long, depending on the proposed threat. A buck accidentally stumbling into a territory will be chased (sometimes rather half-heartedly) to the boundary, while a genuine contender may be chased well beyond the territory boundary. I have seen a master buck pursue a challenger across two fields without any obvious intent to stop. - Credit: Marc Baldwin

We don't get to see skirmishes very often and photographic or video evidence is rare. Most seem to be very brief, less than one minute, and take place either in dense vegetation and/or under the cover of darkness. Indeed, perhaps as a testament to the infrequency with which we see them, in an article to Shooting Times & Country Magazine in January 2008, Ian Valentine wrote:

They don't seem to use [the teeth] to fight with, but rather as a front. In the rut there tends to be a lot of power walking and chasing, but no fighting as such.”

Fights may be relatively rare, but when they do occur they're highly energetic, almost balletic, and several authors have referred to them as “dances”. The tusks are also very much a part of combative technique, and as early as 1945, the 12th Duke of Bedford noted:

They do not fight a great deal among themselves, and when they do fall out it is not always easy to discern the cause; but such disputes as they have are fairly vicious. The rivals dodge round each other, dashing in repeatedly to attempt a cut on the top of the shoulder, and when one of them runs away the victor pursues him for some distance as hard as he can go, trying to give him something to remember him by in hooking him on the top of the rump!

Two bucks involved in a serious fight in Norfolk. During these kinds of intense interactions, the aggressor makes a chirruping noise. - Credit: Mike Mckenzie

The following year, former Zoological Society of London veterinary officer James Aitchison described, quite evocatively, bucks:

“... raising their heads and striking downwards at their opponents with both tusks, viper-fashion

Despite the image painted by Aitchison, the canines seem to be used in more of a slashing than stabbing capacity, inflicting both scratches and deep wounds. Presumably, stabbing an opponent runs the risk of tusk breakage or other injury to the aggressor as the target moves; and there is much movement. Stadler wrote of bucks in close neck-to-neck and/or head-to-head contact, akin to the halskampf or “neck fight” that Rosl Kirschofer described in the similarly-tusked mouse deer (Tragulidae) in 1961, the bucks jumping to and fro in front of one another with neck and head held at 30 to 60 cm (1-2 ft.) above the ground, each chittering and striking out with one or both front legs. The aim of the to-ing and fro-ing seemed to be to get in a position to deliver a canine blow and, during one intense fight between two ear-tagged males shortly after 11:00 one mid-January morning in 1989, Stadler described how the bucks engaged in:

“... a vicious dance for about 45 seconds (the longest fight seen up to that date). During the dance, both males deliver an uncountable number (> 20) of canine-blows aimed at the rump, back, flanks and neck of the opponent.”

Two water deer bucks engaged in brief conflict during December 2022's rut. The fight between males of this species has been described as a "dance"; a reference to the acrobatic nature of combatants. Note the "whickering" sound produced by the aggressor during the fight. - Credit: Sharon Scott

The victorious male was then described as appearing “dizzy”, standing motionless for six minutes, and having sustained a 6 cm (2 in.) open wound on left carpal joint and “a rather tattered coat”. Stadlers observations and those of others point to males attempting to kick or bite/slash the other on the neck, shoulder or rump. As each tries to protect his side and bite the other at the same time, the bucks circle.

The only fight photographed in the northern reedbed at Woodwalton Fen was captured by Gary Dean just after 15:00 on 19th Dec 2009. It lasted for only 12 seconds and during that time one deer “danced gracefully, but menacingly” around the other. In February 2013, Mike McKenzie photographed two bucks fighting at Claxton in Norfolk, during which they circled one another. A very brief clash caught by Sharon Scott on her trailcam during early December 2022 showed one buck leaping over the other, swinging its rear out of the way of the master buck's tusks.

The photos taken by both Dean and McKenzie show the deer circling one another anticlockwise, and this is something apparent in the handful of other videos I have seen of their rutting behaviour. At Woodwalton Fen, Arnold Cooke noticed that damage to ears tended to be on the left side, rather than the right, implying a propensity for bucks to circle/dance in an anticlockwise direction. Cooke observed that 20% of the 211 sightings of bucks across three winters on the reserve had damage to one or both ears, while only 1% of 305 does/yearlings had similar damage over the same time frame. This suggested that ear damage resulted from fights, rather than being inflicted incidentally, by thorns or barbed wire for example. Based on 22 years' worth of sightings, Cooke found 126 instances of ear damage, of which 78 (62%) was to the left ear, 41 (33%) to the right and 7 (5%) to both ears; a statistically significant trend towards left ear damage. In a short article to the journal Deer in 2013, Cooke speculated, based on his data and the two photos provided by Stadler in his thesis, that left side damage might be more likely if bucks moved to their right during conflict, each exposing their left side (and ear) to their opponent - i.e., they move anticlockwise.

Fights can be serious and result in injury to one or both parties. It's not uncommon for mature bucks such as this one to suffer torn ears, broken tusks and damaged eyes, as well as slash wounds to the shoulder, flank and (particularly) rump. - Credit: Marc Baldwin

One final note regarding the combative behaviour of males is an unusual description from Sharon Scott in early January 2021. Sharon spent a couple of hours watching males rutting during a very cold spell, the air temperature around freezing. Several females were lying down, and a male was encircling them, chasing off interlopers. Along with the circling and lunging, she described a “chest clashing” behaviour during which “they put their heads back and charge at each other, butting their chests together like walruses do”. Sharon has never seen them do this before and neither Arnold Cooke or I have observed it, nor come across descriptions in the literature. Sharon also described to me how she watched two larger bucks “beat up” a smaller one during December 2022, after which the defeated animal, lying in long grass, was approached and vocalised to by a female.

While fights may not always result in injury - Raymond Chaplin, for example, noted how in the five challenges he watched at Whipsnade where a fight occurred, neither buck made physical contact with the other - it is common for males to have tufts of fur missing on (sometimes raked from) their backs and nicks in their ears, which appear indicative of at least minor contact during fights with other bucks. Tufts of fur are frequently found on the ground during the winter in areas with established water deer populations, again presumably dislodged during skirmishes. Eye damage, broken tusks (often one, but occasionally both), rump injuries and a pronounced limp are also relatively common among males, and I have observed what appeared to be a shredded nose in one buck that was presumably caused during combat. Chaplin reported catching three bucks at Whipsnade that an eye punctured and two with “the skin of the chin torn and hanging loose”.

Pursuing bucks often attempt to slash/kick at the rump of the fleeing animal and this can result in deep lacerations. Here, what I believe is a first winter bucks sports several rump injuries visible by the disturbance in the fur. - Credit: Marc Baldwin

Slashes from the tusks can be deep, and while those inflicted to the rump of a fleeing buck may not be life-threatening, they can prove an avenue of infection and/or result in disability. In March 2021, for example, Paul Childerley observed a buck sustain a large gash on its haunch, measuring approximately six centimetres (2.4 in.) in length and about two centimetres (0.8 in.) deep, caused by a slash from the tusk of a pursing male. Likewise, Whipsnade veterinary reports from the 1970s and 1980s contain several reports of water deer dying from injuries sustained during fights. During Stadler's Ph.D. studies at the zoo, 56 animals were found with some sort of injury, 44 (79%) of which were males. Of the injured males, 40 (91%) had injuries that could be attributed to intrasexual fighting and included, Stadler writes:

“... smashed eyes, ripped ears, long scars (5-30 centimetres [2-12 inches]) on virtually all parts of the body, or limping legs. In one case, a male was evidently killed during such a fight.

The latter case to which Stadler refers was an adult male found dead in one of the grass fields on 3rd December 1987, having died the previous night. A post mortem revealed two puncture wounds in the buck's heart; the shape of each hole and their separation corresponded with the water deer canine profile and distance, suggesting it had been stabbed through the heart by the tusks of another buck.

Thermal image of a buck on patrol. During the rut, much of a buck's time is spent patrolling and scent marking the core of his territory. This may be only a few metres or much larger, depending on the habitat and dispersion of females. Patrolling bucks typically hold their tail out horizontally, although this may be an artifact of recent defaecation, stopping frequently to paw the ground. A few faecal pellets and/or drops of urine are deposited into these scrapes and nearby vegetation may be bitten. Forehead marking is also known in this species and bucks will sometimes spend a minute or longer rubbing their face on vegetation, depositing scent from their small preorbital glands. - Credit: Marc Baldwin

I'm aware of two descriptions of vanquished bucks having been caught by their pursuer - neither attempting to fight. Feer described how one subordinate laid down in a submissive position, neck and head completely flattened to the ground; the dominant buck only attempting to bite if the subordinate raised his head. Feer commented that 'the fully prone stance had a bite-inhibiting effect'. Bob Lawrence, writing in the Shooting Times and Country Magazine during March 1982, described how:

The chases usually end with the loser evading his pursuer in cover but in one extreme case I witnessed the victor standing over the vanquished which was lying exhausted on his back with all four feet in the air, squealing like a pig.

Interestingly, his 1973 book Beasts in My Belfry, the late Gerard Durrell also described a buck screaming persistently when caught in a way that 'made pig slaughter sound like music'. One of his colleagues remarked on this being the way a water deer accepts its fate.

Two bucks in Norfolk engage in a scrap. This footage is slowed to 60% of normal speed to illustrate how the males "bow" from side to side and twist around. As is quite common, in my experience, these two separate without any physical contact being made. - Credit: Marc Baldwin

It is typically the males that are aggressive during the rut and the female seems to play no part in the maintenance of a territory/stand, although females may exhibit agonistic behaviour outside of the rut and this, and other social interactions of both sexes, is described in Behaviour and Social Structure.