Scotland's largest surviving mammal is an integral part of the Caledonian Forest. Deprived of its native habitat by centuries of deforestation, it will benefit from the return of the forest.
Red deer are widespread but patchily distributed in the Palaearctic region, from Ireland eastwards to China and from just south of the Arctic Circle in Norway to North Africa. The North American population, where they are known as wapiti or elk, occurs throughout large parts of western Canada and the USA, and is considered a distinct subspecies (Cervus elaphus canadensis), although some scientists treat it as a separate species (Cervus canadensis) in its own right. Red deer are very adaptable and have been introduced into Argentina, Chile, Australia, New Zealand and Kentucky in the USA, either for deer farming or for sporting interest.
Distribution in Scotland
Within Europe, Scotland has the largest population of red deer, almost 30% of the European total. The current concentration of red deer is centred in the Highlands and Islands and the southwest of Scotland. They have been present since at least the end of the last Ice Age but it is only in the Highlands that they have survived without a break in that time. Formerly, red deer were abundant in the extensive woodlands which covered most of Scotland but their range began to diminish 5,000 years ago due to forest clearance by people. By the mid to late 18th century their population was at its minimum because of extensive forest loss for agriculture, industrial demands for wood, hunting, and sheep farming purposes. They became extinct from most of the Scottish lowlands by the end of the 18th century (and from much of England and Wales at about the same time) and most deer were living in marginal mountainous areas of the Highlands.
In the 19th century deer stalking became fashionable and with sheep farming becoming less profitable this led to large tracts of land being dedicated to deer, allowing their numbers to increase. From 1883 to 1912 'deer forests' (open hill land that is managed specifically for deer) nearly doubled in size from about 800,000 hectares to over 1.5 million hectares. Many Highland estates today still maintain high deer numbers and the current population is estimated to be 350,000 individuals, more than double the number in the early 1960s.
Physical characteristics and behaviour
The red deer is the largest surviving wild mammal in Scotland. It makes an impressive sight even when seen at a distance, and an adult measures between 105-120 cm in height at the shoulder. Their weight is variable depending upon the food available and, in the Highlands, stags average between 90-140 kg and hinds 65-70 kg. However, most deer in Scotland are not reaching their full potential size because of a combination of living in high densities and surviving on a limited range of food plants in a degraded landscape outside their natural forest habitat. Prehistoric remains of red deer show them to be have been considerably larger than present day animals. Antlers with up to 22 tines or points have been discovered preserved in peat bogs in Roxburghshire, whereas today a stag with 12 points on its antlers is known as a 'royal' and is considered a prime individual. Complete skeletons have also been found, and these indicate that deer were up to one third larger in the past. On mainland Europe today deer still grow to such a size, as they live in forested areas. By contrast, almost 80% of the deer in Scotland live on open ground, but the cost of this adaptation to a less favourable habitat has been a reduction in their size.
The diet of red deer in Scotland today is comprised of grasses (mainly Agrostis spp. but also including some Festuca spp.) and dwarf shrubs, such as heather (Calluna vulgaris) and blaeberry (Vaccinium myrtillus), with heather being particularly important during times of winter snow. Red deer will also browse on trees, especially young ones, and their preferred native tree species are willows (Salix spp.), aspen (Populus tremula) and rowan (Sorbus aucuparia).
Throughout the year the deer will forage in different areas. In summer they move upslope to high ground, to avoid midges (Culicoides impunctatus) and other biting flies, and in winter they frequent lower lying areas, where more food is available, and also to gain shelter from the cold. Feeding grounds also vary between the sexes, with the hinds concentrating on the better, relatively grass-rich habitats, while the stags usually graze on the poorer, heather-dominated areas. Deer droppings take the form of a mass of oblong-shaped pellets, about 2 cm. in length, which are dark brown or blackish in colour.
In summer the adult deer have a distinctive reddish-brown coat which becomes darker brown or grey in the winter, with the rump, belly and inner thighs remaining buff-cream or yellow. Calves are born with whitish spots on their coats, but these disappear with the first moult, when they are about two months old.
Red deer have a number of external scent glands, and these serve a variety of functions, including the scent marking of areas and as indicators of sexual fertility in the hinds. They may also enable animals to identify each other on an individual basis. Deer have a keen sense of smell, while their eyesight and hearing are also acute, and the muzzle is a sensitive tactile organ. As highly mobile ungulates, they are able to travel long distances quite easily, and they are also strong swimmers - a fact which has enabled them to colonise many of the Scottish islands.
Only the males grow antlers. The branched antlers are solid bone and are shed and regrown annually, unlike, for example, the hollow horns of sheep which are retained for life. Once the antlers are cast in April or May, they start to grow again almost immediately and within three months are fully grown, becoming progressively more branched as the stag becomes older. Regrowing antlers every year is very demanding, in terms of the nutrition which is required to produce them, but it does mean that the stags have a full rack of healthy antlers at the beginning of the rut, or mating season, each year. If, instead, they retained their antlers, any damage would lead to a life-long disadvantage in the annual contests which determine whether they breed or not. Deer will often gnaw and chew shed antlers, especially in the nutrient poor areas which occur in many parts of upland Scotland, as they provide an important source of calcium and phosphorus.
The growing bone core is protected by a layer of skin, known as velvet. When the antlers are fully grown, by July or early August, the blood supply to the velvet is stopped, which then begins to putrefy and peel off. The antlers become desensitised as the nerves die, and the stags will thrash or fray trees to help clean the velvet off. Antlerless stags, known as hummels in Scotland, are rare but they can breed and their male offspring will grow antlers.
In late August and early September, hormonal changes in the stag bring about maturation of the gonads, thickening of the neck and hair to produce a shaggy mane, and development of the larynx. With its antlers now fully grown, the stag is ready for the rut. The bachelor herds that are maintained for most of the year now split up and come late September the roaring of stags can be heard echoing around the glens. This is the beginning of the rut when the stags compete against each other for the mating rights of a group of hinds, called a harem.
If a stag does not control a harem, he has little chance to mate. A stag holding a group of hinds will defend them vigorously, to the extent that he may not feed day or night. As a result of this, and the energy expended in physical contests with rivals, an individual stag will typically lose about 14% of his body weight during the rutting season. A challenge to a harem holder will begin with him and his rival roaring repeatedly for 10 to 20 minutes. If the challenger is out-roared by the harem holder, he will usually back down at this stage. If, however, he pursues his challenge the two stags will begin walking parallel to one another eying each other until one turns and lowers his head, as if to invite his opponent to do the same. The next moment there is an impressive clash and the antlers lock. Each stag attempts to push and shove his rival backwards, into submission, and the fight may go on for more than five minutes. Serious or even fatal injuries can result from these battles, and broken antlers are common. Occasionally, the antlers of fighting stags can become inextricably locked, with the animals unable to separate from each other - a situation which leads to both combatants dying of starvation and exhaustion.
Once the rut is over the stags will leave the matriarchal herd and eventually regroup with other unrelated stags over the winter. Most of the deer within a herd of hinds are related and the young males in the group are offspring that will remain with them until they are 3 or 4 years old. Female deer tend to stay in the locality where they were born and have overlapping ranges with their mothers - they are said to be hefted to that area. In contrast, maturing stags will disperse more widely when they leave the matriarchal group and usually move to a completely new range.
A hind that has conceived during the rut will begin to wean her current calf in December or January. If she has not conceived she may continue to feed her calf until it is 18 months old. After a gestation period of 33 weeks the hinds give birth to calves which weigh on average 6.5 kg. Birthing begins in late May and continues through to late July, with the majority of calves being born in early to mid-June. A hind will normally give birth in a standing position, and the calf will begin to suckle within 40 minutes. After the placenta has been expelled, the hind will eat it and clean any traces of the birth from the area, to minimise the risk of attracting predators.
During the first few days the calf will suckle every two to three hours, but the frequency of feeding slowly decreases after that. During suckling the hind will eat the calf's faeces and urine, to reduce the risk of the scent drawing predators. The highest rate of deer mortality occurs during the first year of life, with 80% of the deaths taking place in the week after birth. The main causal factors are bad weather and predation, with both foxes (Vulpes vulpes) and golden eagles (Aquila chrysaetos) known to take newborn calves.
At this stage, the mother will leave her calf hidden in long vegetation, visiting it very cautiously two or three times a day to feed it. After two or three weeks the mother will join her herd again properly, with her new calf. The calf grows quickly, increasing its weight by as much as 30 kg. before November, and is usually weaned by the time it's eight months old.
On the open hill a young hind will be ready to breed in her third or fourth autumn, while in wooded areas most hinds become fertile when they are 15-16 months old. A young stag, though sexually mature, will probably not hold a harem until he is six or seven years old. Red deer can live for over 20 years, but such an age is exceptional, and their lifespans rarely extend beyond 15 years. Most stags die at between nine and twelve years of age, whereas hinds will live for a year or two longer. When death occurs by natural causes, it usually does so in the early spring, when food sources are at their lowest point. Such mortalities are heightened in years of cold, wet weather, particularly at the end of winter or the beginning of spring, when many individuals may die of malnutrition and exposure to the cold.
As with other large mammals, deer attract a variety of parasites, including internal or endoparasites such as liver flukes (Fasciola hepatica), lungworm (Dictyocaulus viviparus) and nematodes. External or ectoparasites include ticks (Ixodes ricinus), deer keds (Lipoptena cervi) and the larvae of the nasal botfly (Cephenemyia auribarbis) and the warble fly (Hypoderma diana). To help remove such external parasites, red deer will roll on the ground in areas of dry or dusty soil, and favoured places for doing this can often be seen under old Scots pine trees, where vegetation growth is minimised by the dense canopy above.
Ecological relationships of red deer
Red deer are an integral part of the Caledonian Forest and other upland ecosystems in Scotland. Being such a large mammal, they have a profound effect upon the habitat in which they live, especially where they are found in large numbers. Deer density varies from less than one deer per square kilometre to over 40 in some areas of Scotland, such as Glencripesdale in north Argyll. In the 1950s, Sir Frank Fraser Darling reckoned that an average of five deer per square kilometre would ensure spontaneous forest regeneration and this figure has by and large been proved correct, although local conditions, including soil quality, the number of tree seedlings on the site, or the presence of other grazing animals such as sheep, can affect it.
Where deer numbers are high, they have a significant impact on vegetation, and will prevent the natural regeneration of both the trees and the ground flora in native woodland. Even less preferred tree species, such as Scots pine(Pinus sylvestris), birch (Betula spp.) and juniper (Juniperus communis), are unable to regenerate at all, if the deer density is too high. Fenced exclosures, such as that at Coille Ruigh in Glen Affric, provide a powerful example of how vegetation growth is suppressed by excessive numbers of deer - since the fence was erected in 1990, it is not only the young trees which have been able to grow again successfully and in abundance, but also other native flora such as creeping ladies tresses orchids (Goodyera repens), and bog myrtle (Myrica gale).
At lower numbers, however, deer have a beneficial influence on the forest ecosystem. For example, the trampling of their hooves can help to expose the soil, thereby providing suitable germination sites for the seeds of Scots pine, and grazing can help to maintain a greater diversity of plant species. Red deer can also play a significant role in maintaining open habitat. This is one of the important ecosystems of the uplands in Northern Scotland as it supports rare species such as the golden plover (Pluvialis apricaria) and dunlin (Calidris alpina).
In the past, red deer numbers were kept in balance with their forest habitat by natural predation, principally by the wolf (Canis lupus), although the lynx (Lynx lynx) and European brown bear (Ursus arctos) would also have taken young calves. These predators maintained the health of the deer by weeding out the old, the weak and the very young, thereby helping the overall population to become fitter and stronger. With these predators all now extirpated from Scotland, the general health of deer herds is less than it would be in an intact ecosystem, and although humans have hunted deer for a long time they do not replicate the effects of other predators.
In the past, deer stalkers concentrated mainly on hunting stags for trophy purposes, shooting the best individuals and leaving the weaker males and the hinds mostly untouched. This led to an artificially biased population and has encouraged high deer numbers. This is now being redressed through the establishment of higher cull figures, especially for hinds, and the coordination of culling efforts over larger areas. Stalkers today seek to maintain the health and vigour of their stag populations through selective culling, but it is much more difficult to do this for the hinds. Lacking distinctive antlers, individual hinds are harder to recognise, so it is not easy to select the most appropriate (ie the weaker or less fit) animals to shoot. In the past, deer would also have completely avoided areas in the vicinity of wolf dens, and the beneficial effect this would have had on local tree regeneration cannot easily be replicated by human practices.
Another major difference between natural predation and human culling is that in the former, the nutrients represented by the deer's body mass were retained in the ecosystem, both by providing food for the wolves and as carrion for other wildlife. With the advent of stalking and culling, the deer carcasses are now all `extracted' and the meat sold for human consumption, which represents a net loss of biomass and nutrients to the already impoverished ecosystems of the Highlands. A red deer carcass is a good source of food for carrion eaters such as golden eagles, foxes, buzzards (Buteo buteo), ravens (Corvus corax) and even badgers (Meles meles). A study in Strathglass showed that almost one third of the diet of the local pine martens (Martes martes) was carrion, and 99% of the carrion was comprised of deer. Deer carrion also supports a diverse range of invertebrates, while deer droppings provide a fertile growing medium for various species of fungi. Shed antlers also provide a food source for small mammals such as wood mice (Apodemus sylvaticus) and voles (Microtus agrestis).
An increasing problem with Scotland's red deer population is the threat to the species' genetic integrity because of interbreeding and hybridisation with sika deer (Cervus nippon), which have been introduced from Japan. In some regions, such as parts of the Lake District in England, the deer population now consists almost entirely of red-sika hybrids, and the front line of the area affected by such hybridisation is expanding at the rate of seven kilometres per year. Unless effective remedial action is taken to address this problem, it has been estimated that in due course the only pure red deer in Scotland will exist on isolated islands.
Although red deer have survived the near total loss of their native habitat - the Caledonian Forest - in Scotland, they have nonetheless suffered the effects of this deforestation. As early as the end of the 19th century it was recognised that the decline in body size of red deer was linked to the decline of the forest through human exploitation and in 1920 James Ritchie wrote - "A broad reading of the facts shows indubitably that the destruction of the forest has impelled the Red Deer of Scotland on a downward path, limiting its numbers, decreasing its range, and whittling away its former dignity by steps of physical decadence."
Red deer, through their excessive numbers and overgrazing, are sometimes seen as the main problem preventing the regeneration of the Caledonian Forest today. However, the ecological imbalance between native forest cover, numbers of grazing deer and lack of natural predators has been caused by humans, not the deer. The work being carried out now to help restore the Caledonian Forest should ensure that, in the future, red deer will once again have a proper habitat to live in, thereby enabling them to thrive in larger body size and better health than they do at present.
Deer - related pages
Published: Caledonia Wild! Spring 2000
Last updated: 25 August 2010