Rabbit down, deer up

Contrary to what you might imagine, our understanding of the changing fortunes of Britain’s mammal populations is far from complete. In fact, it turns out that we have very little knowledge of just what has been happening to many familiar mammal species over the last two decades. This lack of information contrasts with what we know about birds, primarily because mammals tend to be more secretive than birds and, therefore, that much more difficult to monitor at the population level. Additionally, many of our mammal species are nocturnal in habits or occupy habitats that make them hard to observe.

The information that we do have tends to come from periodic national surveys, but these are usually expensive to run and so only tend to take place once every few decades. Annual monitoring, which can be key to understanding how and why populations change, is limited to just a handful of species, a number of which are actually monitored by birdwatchers participating in national surveys, like the weekly BTO Garden Birdwatch or the annual BTO/JNCC/RSPB Breeding Bird Survey. These birdwatchers have been kind enough to take on some additional recording of other taxa. Such surveys have underlined the decline in hedgehog populations nationally and, more recently, have flagged up a worrying decline in our rabbit population, which fell by 48% over the period 1995 to 2012. It has also been possible to detect regional declines in some of the more widespread species. For example, the fox population in England fell by 27% over the same period.

Some species have increased in number, with one group – the deer – showing a particularly pronounced increase in their populations. Living in Norfolk, we will all be familiar with the increasing numbers and distribution of muntjac, an introduced species that became established here after escaping from private collections. Nationally, its numbers have increased by a staggering 191% since 1995. Less dramatic, but still significant, increases have been charted for red deer (up 71%), fallow deer (up 89%) and roe deer (up 60%). Such increases have already had an impact on habitats and the other species that use them, underlining the importance of collecting reliable information on a regular basis to support conservation action.

Introduced deer

It is at this time of the year that the local muntjac turn their attentions to the flowerbeds and shrubby borders of the garden at work. Over the years we have discovered which of the plants in our wildlife garden are on the menu for these introduced deer and which are not. In part, selection appears to be driven by the weather and feeding conditions elsewhere. When times are tough, less favoured plants and shrubs may find themselves back on the menu and over recent days the deer have been much in evidence.

The presence of muntjac can be seen in our woodlands as well. Crouch down and look across the woodland floor and you’ll soon spot a clear browse line, below which the deer have stripped back much of the vegetation. The impact that such browsing has goes beyond the damage it does to the plants themselves. The herb and shrub layers in woodland provide important habitat for insects, cover for small mammals and nesting opportunities for birds like blackcap, willow warbler and nightingale. Increasing deer numbers have been shown to reduce the local populations of some of these species (e.g. the nightingales in Bradfield Woods) but the effects are not always negative. Browsing can, for example, sometimes open up more of the woodland floor, providing habitat for butterflies whose foodplants, unpopular with the deer, get a chance to increase in numbers now freed from competition.

Originally from south-east China and Taiwan, the muntjac was introduced to Woburn Park in 1894, from where the species was then released into neighbouring woods. Further releases, escapes and translocations have followed and the species (more correctly called Reeves’ muntjac) is now well-established across much of England, with a population thought to be in excess of 50,000 individuals.

Unlike the roe, red and fallow deer that are also to be found in the Brecks, the muntjac can be surprisingly tolerant of our presence. Those individuals using the garden at work or the scrubby habitats that border the river will tolerate a reasonable approach, particularly if you keep quiet and still. Sometimes there may be three or four of these compact deer browsing on the edge of the lawn and seemingly uninterested in the staff that traipse to their cars parked nearby.

Keeping these compact deer out of a garden can prove difficult. Their small size and great strength allows them to force through or under fencing and they are even capable of jumping a four foot wall (as we discovered in our town centre garden several years ago). They do remain a conservation issue, albeit one that is unlikely to ever be resolved, so perhaps we should learn to live with them.

The changing of the guard

I begin my walk in darkness, part of a daily ritual at this time of the year. Stepping out into the gloom of the forest with the dogs, I am otherwise alone. I know this patch well and the dark, sometimes shifting, shapes and sounds of the forest no longer hold any fear for me. The sound of something large moving through the vegetation will be one of the many deer and the upright figure that haunts the edge of the track will be a now familiar piece of broken trunk. For many the darkness of night is an unsettling experience, no doubt a reflection of our reliance on the visual. Perhaps we hold within us some primitive fear, an echo perhaps, from our ancestors whose wild woods held the threat of large carnivores long since lost from our countryside.

I have always enjoyed the sensation of being out at night, away from the pervading light pollution that spoils so much of our landscape. The darkness reins in our sight but heightens other senses, most notably those of hearing and smell. The damp, soft air of the forest night holds onto the smells of passing fox and muntjac, and carries the harsh calls of territorial tawny owls and the high-pitched notes of nocturnal migrants like redwing. Whether it is the warm, moonlit summer nights out ringing nightjars or, as now, the pre-dawn walks on damp winter mornings, the dark of the forest embraces you, shortening horizons and engaging you more closely through senses that strain to grasp at sounds and smells.

There have been times, however, when some of night’s sounds have unsettled me. The crack of a rifle close-by or, once in a chestnut wood in Sussex, the sound of footsteps following my nocturnal perambulations. It turned out that the source of these footsteps was a pheasant that had been following me as I worked my way around a regular beat (at the time I was monitoring small mammals with live traps baited with grain). The pheasant had learnt that when I caught something I emptied the grain out and replaced it. My laughter upon discovering this was clearly an outlet for the tension of my nervous energy!

Night’s dark shroud can be slow to slip away on these winter mornings, particularly when the moon is spent or the cloud thick. As the deer retreat from the rides and clearfell, to seek shelter in the thickets and forest cover, so other creatures are stirring. Noisy wood pigeons, roused by my approach, explode from their treetop roosts in a crash of flapping wings, while the calls of crows hang in the air. The world is waking, and it is time to turn for home and breakfast.

Riverine

Having spent much of the day in the house, the weather outside a succession of heavy showers, I feel a need to go out and get some air. It’s late afternoon and a suggestion that the sun might be breaking through gives me the impetus that I need and I head down to the river. The walk is brisk, easing the stiffness from my joints and clearing the day’s paperwork from my mind, and I cut through the still dripping wood and strike out towards the meadow.

I like this bit of the river. It is off the beaten track and you have to pick your way through rank vegetation to rediscover its meandering course. The scattered Alders chart the river’s route through the meadow and I am soon settled on the bank, screened on three sides by nettles and rough grasses. Because movement through this bit of meadow is difficult and noisy, it is impossible to approach any animals or birds without scaring them away. I find that the best approach (as it is in many habitats) is to find a suitable spot in which to settle and to wait patiently for the wildlife to approach you.

I have not long been settled when the sun fades behind a thickening blanket of cloud, heralding the approach of another squally shower. At first the smooth surface of the river reveals just a few spots of rain but then, increasingly, the ripples coalesce as the rain’s intensity increases. With several layers of clothing, including a goose-down jacket and a waterproof, I will be dry enough but I hunch forward, drawing my legs up to protect my camera bag. From under my hood I still have a good view and watch the approach of a male Muntjac. He has not seen me, or if he has, he has mistaken me for a large grey mass, perhaps a rock or unmoving pile of decomposing vegetation. It is wonderful to be able to watch unseen, the deer browsing intermittently as it passes by just a few feet from me.

The rain strengthens further, becoming a rush of hail, noisy on my hood and reducing the visibility such that I lose sight of the Muntjac. Just as quickly as it arrived so the hail halts and, soon after, the rain too. A Grey Heron drifts in on broad wings; legs held below it drops to the opposite bank. It seems unsure but I cannot tell if it is my presence or the fact that there is no obvious route for it to take into the water, such is the growth of emergent bankside vegetation. The heron lifts itself away with strong strokes and the river is mine alone.

Norfolk's deer revela our influence

Norfolk is well represented when it comes to deer, with six species currently established within the county. While it might seem fairly straightforward to divide the six species into native (Roe and Red) and introduced (Fallow, Sika, Muntjac and Chinese Water Deer), things are not quite what they seem. The presence of all six species within the county owes a great deal to our activities and to the deliberate introduction of animals for sporting or personal interests.

Like the Red Deer, the Roe is an ancient inhabitant of Norfolk, its bones present in the fossil and archaeological record. However, both species were lost from the county historically, only to be reintroduced from imported stock. Red Deer had become extinct across much of England and Wales by the end of the Eighteenth Century and the same is almost certainly true for the Roe within East Anglia. The Roe that are present here today are most likely of German origin, the descendents of individuals introduced to Warren Wood, near Thetford, in 1884 by William Dalziel Mackenzie.

Other species have a longer pedigree, as in the case of Fallow, brought in to populate the 40 or so deer parks established within the county since Doomsday. Red and, in one case, Sika Deer were also used to stock Norfolk’s deer parks, which were status symbols for those wealthy enough to be able to build and maintain them. The earliest of our deer parks appears to be Costessey, dating from around 1086. Like the majority of our other deer parks, that at Costessey was lost many decades ago. Many disappeared during the Civil War but three remain today, two well-known and well-maintained and one about which I know rather little (but would like to know more). The two big parks are at Holkham (completed by 1759) and Houghton (completed in 1722); both have magnificent herds of Fallow, that at Houghton managed to favour the white form of Fallow, that at Holkham with the standard form. The other park is at Melton Constable, reputed to support 300 animals, roughly evenly divided between Red, Fallow and Sika, but since it does not have the sort of public access associated with Holkham it is difficult to know how the herds are doing.

One of the reasons for the demise of deer parks was the expense of maintaining them. Holkham has some nine miles of wall (which took six years to construct) and the maintenance costs are high. As land has changed in value, it has not always be easy to maintain large areas outside of agricultural production. Deer have from the parks and it is the descendents of these that are now doing so well in the county.

A wet walk

I have been marking time. Brooding over the weather, the wind and rain confining me to the house, I have been studying maps and planning which parts of the county to explore in the warmer, more welcoming, days of spring and summer. Deciding that this won’t do, that the weather will not restrain my wanderings, I dig out a thick woollen hat and my waterproof and head out. With so much water in the air and seemingly oozing from the sodden ground I am drawn towards the river. The waters are brown with silt washed from the fields; in places they push their way up towards the lip of the bank, as if straining to reclaim the vast puddles that cover the bankside path. The thin, elongated, fallen leaves of a willow carpet the ground. Sodden with the rain, their grey undersides resemble small, lifeless fish, disgorged by the angry waters.

Temporarily the path leads me away from the river, skirting a field and a small piece of alder carr, and here I encounter a muntjac. This one is a female, squat in shape and hunched against the elements it is uncertain at my approach, moving off slightly before turning to stare at me intently. Its thick coat must provide a good degree of protection from the rain. Finally, a decision is made and the small deer turns and is soon lost from view amongst the dripping vegetation. There is a real sense of decay in this wood; the fallen leaves and timber, last year’s growth that has died back, all brown and sodden. Only the leaves of the bramble stand out, green and vibrant and screaming of life.

By now the rain has eased somewhat, enough to bring out smaller birds intent on feeding before the light fades. Amid the many blackbirds is a song thrush, its warm tones welcome and lifting my spirits further. Then, as if seeing the song thrush was a good omen, I catch sight of a finch in flight. Heavy and rounded in shape, I follow its course, bringing my binoculars up to catch it land in one of the tall alders that flank the fen. It is a hawfinch, the first I have seen on my local patch and I feel unadulterated joy. I’ve seen these birds before, most winters in fact, at well-known local sites but this one is mine, on my patch and unexpected. Is this reward offered to me as an enticement – look at what you may see if you venture out – or is it pure chance that I stumbled across it? Either way, it is a wonderful bird to see at any time of year, no matter what the weather.

Barking deer

From close by, the short, sharp-sounding bark of a muntjac deer unnerves the dogs. The deer has not heard our approach and can only be 20 metres or so away within the dense vegetation that borders this forest ride. More distant barks are ignored but the proximity of this one is enough to halt the dogs in their tracks. The series of single barks, each separated by a few seconds of silence, suggests that we are close to a female in season, possibly with a male in attendance; it is time to steer a different route and to leave these stocky little deer well-alone.

The dogs are certainly familiar with the muntjac that seem to do so well in and around Thetford Forest. The small hunched form of a muntjac is frequently seen crossing a forest ride and more distant barking is commonplace throughout the year.  The muntjac is an introduced species, originating from southeastern China, and first released at Woburn Park early in the Twentieth Century. Two different species were originally introduced, the Indian muntjac and the Chinese muntjac, but it is the Chinese muntjac that has become established. Standing about 48cm tall at the shoulder, these are small deer, short-legged and stocky in nature. The males have simple antlers which, in mature males, curve backwards and terminate in a hooked point. When alarmed, the short tail is raised and held vertically, displaying the conspicuous white underside – a useful identification feature. The very small hoofprints, with those of the rear feet registering upon those made by the forefeet, are also characteristic.

Muntjac breed throughout the year and young can be born in any month. After birth the female comes into season and will be pursued by a male for some time prior to mating. Each male utilises a home range that encompasses those of several females. Ownership of an area is signalled through scent marking, a behaviour utilised by many other mammal species for social communication. The males, and in particular dominant males, use scent marking to a greater degree than the females. In front of each eye is a large scent gland, which is frequently opened and sometimes everted (resembling a black grape) during courtship. Frontal glands, positioned on the forehead, are used to mark the ground and glands between the digits of the hind foot leave scent wherever the animal wanders. Such communication helps to signal the social status of individual males and is often enough to deflect potential aggressive encounters. These do happen on occasion and may sometimes be directed towards other species seen as a threat, including foxes and dogs – another good reason for me to steer my dogs away from the courting couple.

Are Norfolk's deer becoming a problem?

There has been quite a bit of discussion over recent months about the numbers of deer within the county. This has been part of a wider debate about deer numbers nationally and concerns have been expressed about the impact that they might be having on forestry and farming interests, other wildlife (by damaging woodland vegetation) and through collisions with motor vehicles. Just last week, there was an article on the subject in one of our local newspapers. The debate is an interesting one, particularly so for me in my role as County Mammal Recorder, and it raises a number of important issues centred around the interaction between humans and the other wildlife with which we share the countryside. 


Introduced species, such as muntjac and Chinese water deer, seem to be doing very well within the county and both species have increased in numbers and range over the last few years. Drive along any of the roads through Thetford Forest on a summer evening and you will see several dozen muntjac grazing on the verge during the course of your journey. These small, dog-sized, deer are surprisingly solid and any collision with a motorcar is likely to be damaging to both parties.


Research has demonstrated that at high densities, deer populations damage deciduous woodland by preventing natural regeneration and by removing much of the ground flora. This, in turn, reduces opportunities for other wildlife and is thought to be one of the reasons for the declines seen in a number of woodland bird species. Experiments using deer fences to exclude deer from small blocks within woodland show just how pronounced the impact of deer grazing can be. 


There may be good ecological and commercial reasons for the numbers of deer to be controlled and control through shooting has been an important component of forest management within the county for many decades. As with any control programme, it is important to know how many individuals there are in an area in order that a suitable level of control can be established. In the case of deer this can be something of a problem. Deer populations are not easy to monitor, in part because of their secretive nature, but also because populations may range over large areas. Traditional methods of monitoring mammals, such as recording field signs like tracks and droppings, are not always readily applicable to deer and require a high degree of skill on the part of the observer. Having said this, efforts are being made to build up a more complete picture of the number of deer in our region and various organisations are working together, through the Deer Initiative, to improve our understanding of these wonderful animals.