Mammals in the British Isles

Family Hystricidae

The large South American coypu, Myocastor coypus, which produces the fur known commercially as ‘nutria’, escaped from fur farms in the early 1930s and established feral populations in several places, mainly in East Anglia. It is a large aquatic rodent reaching a length of a yard from nose to tail, looking like an enormous brown rat with webbed hind feet, blunt nose, small eyes and ears, and orange coloured enamel on the front of the incisor teeth. In East Anglia the population increased enormously in spite of heavy mortality in severe winters, so that the animals became a pest to agriculture and a threat to the stability of river banks. Since the early 1960s official control measures have greatly reduced its numbers.

ORDER CETACEA

Although seventeen species of whales and dolphins have been recorded as British, mainly because they have been found stranded on our coasts from time to time, they cannot be regarded as part of the British fauna as dealt with here – the wreck of a foreign ship on our coasts does not give its crew British nationality or make it part of the native population.

ORDER CARNIVORA

Of the ten indigenous species of beasts of prey two have been extinct for centuries; the remaining eight have been joined by a recent introduction derived from animals escaped from fur farms.

Family Canidae

The wolf, Canis lupus, was exterminated some 500 years ago in England and Wales, but survived in remote parts of Scotland and Ireland for another 250 years. Its descendent, perhaps with an admixture of other ‘blood’, the domestic dog, has some effect upon the country’s ecology, killing according to one authority146 some 6,000 sheep a year – in 1978 4,639 were killed and 3,833 injured – and every day depositing 500 tons of dung and a million gallons of urine ‘on Britain’s pavements and parks’, equal to the sewage from four million people.

On the other hand the fox, Vulpes vulpes, is found everywhere in Great Britain and Ireland and in some of the islands. Its abundance is due to its adaptability to various habitats and foods, to its nocturnal and crepuscular habits, and to its tolerance of the near neighbourhood of man as shown by its recent extension of habitat into the suburbs of towns.

Family Ursidae

The brown bear, Ursus arctos, has been extinct in the British Isles for a thousand years; its natural distribution covers all of northern Europe, Asia and America. It varies greatly in size, from the comparatively small European race to the enormous ‘grizzlies’ of Kodiak Island off the Alaskan coast, as large as the ‘Cave bear’ that lived in the British Isles before the last glaciation of the Pleistocene epoch.

Family Mustelidae

The family consists of small to medium-sized carnivores, the British species characterised by long bodies and short legs. The pine marten, Martes martes, as large as a rabbit, with deep brown fur, a yellow patch on the throat, and long bushy tail, is an inhabitant of woodlands, where it feeds mainly on small birds and rodents. It is an agile climber. It was formerly found throughout the British Isles but has long been extinct except in northern Scotland, the Lake District, north Wales and Ireland.

Although the pine marten has been successfully destroyed as vermin in most of Great Britain, two other species, the stoat and the weasel, both subjected to similar persecution, have been able to remain plentiful. The larger of the two, the stoat, Mustela erminea, with head and body length of about a foot in males but some two inches shorter in females, is brown above, off-white below, and has a black tip to the tail. In the northern part of its range the winter coat is white with black tail tip; but in the southern part it resembles that of the summer; partly white examples occur in winter between the extremes of its range. Stoats are found throughout the British Isles and on some of the off-lying islands; those in Ireland, being smaller and having less white below, are recognised as a separate subspecies M.e.hibernica.

The weasel, M. nivalis, about four inches shorter than the stoat in both sexes, is similar in colour but does not have a black tail tip. The winter coat is not white in British weasels, though further north on the continent it is. Weasels feed mainly on voles and mice, whereas stoats take larger prey as well, especially rabbits. They are found throughout the mainland of Great Britain and some of the islands, but not in Ireland.

The polecat, M. putorius, is larger than the stoat but similar in build; the fur is brown with a white patch on the face between eyes and ears, the two often joining to form a bar. There is a white patch under the chin extending up onto the muzzle, and the edges of the ears are white. The ferret is a domesticated form of the polecat, perhaps with some hybridisation with the Steppe polecat of eastern Europe which may be specifically different; as it breeds successfully with the polecat, and some specimens cannot be distinguished either by colour or skull structure, the specific name, M. furo, for it seems superfluous. Albino ferrets are popular with the breeders and users of these animals. The polecat is an unselective carnivore; it was exterminated as vermin over most of Great Britain by the beginning of the twentieth century, but remains common in the greater part of Wales and the Welsh Marches.

The mink, M. vison, a native of North America, escaped from fur farms and became established as a feral member of our fauna in the 1950s; it is now widespread in Great Britain and common in many places – it is also present less widely in Ireland. The mink, about the size of a polecat, with a rather bushier tail, has very dark brown fur with white spots on the chin and throat. It is an unselective carnivore, and the effect of its activities on the native fauna has yet to be assessed – it may not be as destructive as some people have feared.

The well-known badger, Meles meles, grey above and black below, with a fore-and-aft black streak over eye and ear on each side of the white head, is found throughout the mainland of the British Isles and on some of the islands, and is common in many parts. It is a comparatively large animal – weights of over 35 pounds have been recorded – and is so widely spread because it is adaptable to many different habitats, has discreetly retiring habits, and is omnivorous, eating anything from earthworms to rabbits and from fruit, bulbs, and nuts to corn and grass. It comes out to forage at night, remaining underground in its set by day.

The otter, Lutra lutra, on the other hand is restricted in habitat to the neighbourhood of water, and, though formerly found throughout the British Isles and the off-lying islands, is consequently much less common than the badger; since about 1950 it has declined greatly in numbers over most of mainland Great Britain, but it is still plentiful in western Scotland, Ireland, much of Wales and south west England. The aquatic habit of the otter is shown by its webbed feet and broad snout with long tactile whiskers. The fur is brown all over, lighter on the throat, and the tail is long and tapering. The diet of the otter consists mainly of fish, freshwater or marine, for in the west of Scotland it is as much an inhabitant of the sea shore as of fresh waters.

Family Felidae

The wild cat, Felis silvestris, somewhat larger than most domestic cats, is a tabby with dark cross stripes on a grey background, and bushy tail ending in a rounded, not pointed, black tip. It has long been extinct in most of Great Britain and is now found mainly in the highlands of Scotland where it is extending into its former range; it was never native to Ireland. Its food includes rabbits, hares, rodents, and birds. It has hybridised much with feral domestic cats – domestic cats both feral and tame are probably the most destructive of all predators to the small mammals and birds of our fauna.

ORDER PINNIPEDIA

The seals are only marginally part of our fauna, for they are confined to the waters off the coast and to the sea shore from which they come a short way onto land only in remote undisturbed islands. They are, however, animals of particular interest to zoologists, and of unusual endearment to the public in general. Two species live and breed on British coasts; five others are merely accidental vagrants from northern seas, and thus form no regular part of our fauna.

Family Phocidae

The common seal, Phoca vitulina, and the grey seal, Halichoerus grypus, are not easy to tell apart when in the water, unless very close to the viewer. The coat colour of both species varies greatly; the basic pattern is of dark spots on a grey background, the spots tending to be smaller in the common seal, but no two individuals are exactly alike. Bull common seals reach a length of two metres overall, cows about 20 cm less, whereas bull grey seals reach three metres but the cows some 45 cm to 60 cm less. The snout of the common seal is comparatively short, giving the head a rounded appearance and a ‘dished’ profile; in the grey seal it is long and high, giving a convex profile to the head. Both species can be found on many parts of our coasts, but concentrate in special places to form breeding colonies. The common seal is least likely to be met with on the southern and western coasts of England and Wales; it breeds at several places on the east coast, especially in the Wash, in Orkney and Shetland, on the west of Scotland and the islands, and the east of northern Ireland. On the east coast of England the main breeding colony of the grey seal is at the Farne islands; in Scotland it abounds in Orkney and Shetland and many islands of the west. There are also breeding colonies on the coasts of Wales, Cornwall, and much of Ireland. The common seal prefers shallow waters with sand and mudbanks and is often found in estuaries, whereas the grey seal lives in deeper waters off rocky coasts. Both species come ashore to give birth, the young of the grey seal remaining on or above the beach for about their first three weeks, but those of the common seal, born on sand or mudbanks covered at high tide, swim with their mothers from the first.

ORDER PERISSODACTYLA

Family Equidae

Wild horses have been extinct in the British Isles for about 10,000 years, but half-wild breeds derived from introduced domestic horses exist in several districts of extensive unenclosed land.

ORDER ARTIODACTYLA

Family Suidae

The wild boar, Sus scrofa, has been extinct in Great Britain for some 300 years. Although its domesticated descendants have played an important part in the rural economy of Ireland it was never indigenous there.

Family Cervidae

Stags of the largest of our two native species of deer, the red deer Cervus elaphus, stand up to about four feet at the withers, hinds about six inches less. The coat colour varies greatly; in general it is red-brown in summer, grey-brown in winter, with a white patch on the rump. Calves at birth are reddish-brown with white spots, but lose the spots at their first moult at the age of about two months. Horns, now generally called antlers, a term originally meaning the branches or tines, are carried only by stags. They are dropped from the pedicles, from which they grow on the forehead, in spring or summer, whereupon new ones at once start growing and are complete by the autumn. The red deer, formerly present throughout the British Isles, remains as a truly wild animal only in Scotland, the Lake district, on Exmoor and the Quantock Hills, and in south-west Ireland; elsewhere feral deer, often derived from escaped park animals, are present in many places. In Scotland the deer are animals of the hill, but in lowland England they are more generally inhabitants of woodland where they reach greater size and the stags bear larger antlers.

The sika deer, C. nippon, smaller than the red deer but similar in build, was introduced from the Far East in the second half of the nineteenth century, and feral populations have become established in a number of places in the British Isles. The coat is red with light spots in summer, darker and unspotted in winter; the rump patch and tail are white except for a narrow black line on the latter. The antlers of the stags are smaller and have fewer tines than those of the red deer, and lack a bez tine between the brow and trez tines. Sika deer inhabit woodlands from which they come out to graze from dusk to dawn. They hybridize freely with red deer where the ranges of the two species overlap.

The fallow deer, Dama dama, is another introduced species, but has been adopted into our fauna for a much longer time – probably almost a thousand years. It has for long been a favourite ornament in parks from which it has escaped so that feral populations are widespread in England, Wales and Ireland, and are found in some parts of Scotland; those in Epping and the New Forests probably represent the early stock. Bucks stand about three feet high at the withers, does a few inches less; the antlers of the bucks are usually handsomely palmated. The colour varies greatly but is light with spots in summer, much darker and generally without spots in the winter. The border of the white rump patch is black, as is the upper surface of the tail.

The roe deer, Capreolus capreolus, is a true native of Great Britain but not of Ireland. It is plentiful in Scotland and northern England, but has been introduced into southern England, and into East Anglia where it was exterminated some two hundred years ago. It is a small deer, barely two feet six inches at the withers, with no visible tail. The colour is tawny red, the muzzle black and the chin white; in the darker brown winter coat two white patches appear on the throat. The antlers of the buck are short spikes each with one forwardly directed tine at the base and a backwardly directed one at the top. Roe live in woodlands, which they leave to browse on bushes at dawn and dusk.

Two other small species of introduced deer are at large in parts of England, descended from animals that escaped from captivity during the present century. The muntjac, Muntiacus reevesi, is widespread through much of south, central and eastern England, and is still increasing its range. It is not more than eighteen inches high at the withers; the coat is deep chestnut in colour, lighter below. The antlers are short spikes carried on long hair-covered pedicles prolonged forward as ribs on the face. Muntjac live in dense cover where they are more easily heard than seen, for they utter a short sharp bark repeated many times when disturbed. The Chinese water deer, Hydropotes inermis, is slightly larger, reddish to greyish brown, and with large ears; the bucks do not have antlers but long upper canine teeth that project from the mouth as tusks nearly three inches in length. Water deer live among long dense herbage on which they graze – they are less widespread than the muntjac, being feral but numerous in parts of Bedfordshire, Northamptonshire, Buckinghamshire, and Huntingdonshire.

Family Bovidae

Cattle, sheep and goats do not exist in the wild in the British Isles. Wild cattle, from which domestic cattle are descended, have been extinct in Great Britain for some three thousand years – the ‘wild’ white cattle preserved in several parks are derived from domestic animals. A primitive breed of sheep, the Soay breed, has long been present on the island of the St. Kilda group to which it gives its name meaning ‘Sheep island’; it is derived from domestic stock. The ‘wild’ goats that are feral on mountains or islands in various parts of the British Isles are derived from domestic animals, for the species has never been indigenous. The domestic sheep, however, has played an important part in shaping the ecological background of the British fauna, much of our so-called man-made landscape being in fact a sheep-moulded landscape.

In the chapters that follow we consider the biology of this mammalian fauna, enquire into its origin and present distribution, and investigate the way of life of its various members, and how it shares the approximately 75 million acres of its homeland with over fifty million human beings.

CHAPTER 2

ICE AGES

THE small number of mammalian species now living in the British Isles is sometimes spoken of as an impoverished fauna. This is not strictly correct; it is a small fauna compared with those of some other lands, but of the forty-six indigenous species only five have been exterminated in historic times, whereas fourteen that are not indigenous have been introduced and now permanently enrich it. The causes of the present composition and distribution of our indigenous mammalian fauna must be sought in the geological history of the islands.

The basic geological structure of the country has evolved through enormous periods of time during which the rocks were laid down as deposits on the floors of successive seas, or extruded through the earth’s crust by volcanic activity. If we could see from a satellite the events forming the present topography of the earth as in a time-lapse film, so that many millions of years were concentrated into an hour, the tortured crust would appear to be in constant movement, writhing and squirming as immense forces distorted it. The tectonic plates jostling each other or drawing apart to form the oceans, pushed asunder by the material rising between them from below, were sometimes sunk far beneath the sea from which they received deposits of enormous thickness, or thrust up into mountains and lands from which erosion carried their substance back to the oceans – everything was, and still is, in constant flux. During all these upheavals plants and animals were evolving ever since life first appeared on the earth some time in the Precambrian epoch, perhaps as much as three thousand million years ago.

The successive epochs into which palaeontologists divide geological history each had their characteristic faunas and floras which left their remains as fossils in the rocks, representing a biomass, or aggregate of living matter, so great that it is almost beyond comprehension to the human mind. Among this teeming swarm the mammal-like creatures first appeared in the Triassic epoch, which began some 225 million years ago; but ten million years were to pass before the Eutheria, the placental mammals, evolved towards the end of the Cretaceous epoch. In the succeeding Eocene epoch, which began about seventy million years ago, the orders of mammals that we know as living animals were already differentiated together with others that are now extinct.

During the following epochs, the Oligocene and the Miocene, in which great crustal disturbance took place, including the upraising of the great mountain ranges, the evolution of the mammals produced a vast variety of forms which reached a peak in numbers before the end of the Miocene some twelve million years ago. In the succeeding Pliocene, which lasted about ten million years, the land masses gradually took on their present shapes, and mammalian species began to decline in number, a decline that continues to the present day. Throughout these epochs the climate varied from time to time, sometimes temperate, at others cool and wet, or warm and arid, but it was not until the Pleistocene that the greatest climatic change in later geological history took place.

The Pleistocene epoch was comparatively short; it has been deeply studied using modern techniques during the last fifty years so that our knowledge of it increases every day. It was formerly thought to have lasted about a million years, but is now known to have been probably twice as long – some authorities consider it to have lasted as much as three million years. It is popularly called the ‘Ice Age’, a name that over-simplifies the matter, for the ice ebbed and flowed so that mild periods of sometimes almost tropical warmth, separated successive glaciations. At its height ice sheets covered most of Europe, North America and northern Asia, while another covered Antarctica, as it still does.

It was in 1837 that Louis Agassiz, the Swiss and later American geologist and zoologist, first drew attention to the evidence that glaciers had once covered much of the land, evidence which he had discovered in 1836 on his field excursions in search of fossil fishes.4 His views were adopted by the Reverend Dr William Buckland F.R.S., Canon of Christ Church and Professor of Geology at Oxford, later Dean of Westminster, the English pioneer geologist and palaeontologist. He found similar evidence in the British Isles, especially the grooves and scratches scored in rock surfaces of the north, over which glacial ice had flowed engraving the substrate with the burins of its entrapped stones.28

Buckland was the first President of the British Association for the Advancement of Science, and when he addressed the ‘British Ass’ on the subject of glaciation one of his waggish friends drew a caricature of the great man standing on a surface covered with glacial scoriations while at his feet lay two pebbles, one of them labelled ‘specimen no. 1, scratched by a glacier thirty-three thousand three hundred and thirty-three years before the creation’; the other, ‘no. 2, scratched by a cart wheel on Waterloo bridge the day before yesterday.’

Fig. 2. Position of the ice edge at maximum cover of Eurasian glaciation during the Anglian glaciation of the British Isles.

As with all new theories before they become accepted as established truth, the glacial theory at first met with much opposition as well as ridicule – indeed Buckland himself at first strongly disagreed, and it was only during a tour of Scotland in company with Agassiz in 1840 that he was convinced. Thereafter he has strongly supported the theory and, through the evidence of glacial action on polished and scoriated rocks and the presence of morraines, most of the leading geologists of the day agreed with him. He was also the first to suggest that the famous parallel roads of Glenroy in Scotland were the former shore lines of a glacial lake formed by the damming of Glen Spean by two glaciers coming down the north and east sides of Ben Nevis.

The knowledge that the country, and later that all countries on both sides of the north Atlantic, had once been in the grip of an Ice Age stimulated geologists to more detailed research, and it soon became apparent that there had been not one Ice Age but several. The difficulties of identifying and dating them were enormous, because younger glaciations are bound to disturb, distort, and confuse the traces of older ones, as are denudation, erosion, and changes of sea level in the often long intervals between them. Local variations in the extent and intensity of glaciation further complicate the problem.

The basic pattern of the successive glaciations in Europe was appropriately worked out by investigating the glaciations of the Alps, where Agassiz had first discovered evidence of the ‘Ice Age’. About the beginning of this century Penck & Brückner122, after prolonged study of the gravel terraces laid down by rivers rushing forth from beneath the melting glaciers, concluded that there had been four main ice ages separated by long interglacial periods when the land was free from ice-cover and the climate was comparatively warm. They named the four glaciations after rivers flowing down from the Austrian alps to southern Germany, in the valleys of which they examined the fluvioglacial gravels and moraines; the oldest they named Günz, and the succeeding ones Mindel, Riss and Würm.

The last glaciation, the Würm, reached its peak about 20,000 years ago, but it was not so severe or long-lasting as some preceeding ones. During the Mindel glaciation the ice sheets reached their greatest size and covered an enormous area of Europe, much more extensive than that covered in the later Riss and Würm stages. The interglacial stage between the decline of the Mindel and the onset of the Riss lasted nearly a quarter of a million years, during which a contemporary intelligence might have thought that ice ages had gone never to return. Although the Günz was designated the oldest or first glaciation, there are now known to be indications of numerous glaciations older still, hence the differences of opinion between authorities on the probable length of the Pleistocene epoch. There cannot, in any case, have been any sharply defined boundary between the Pliocene and the Pleistocene, for the whole of geological and biological evolution is a continuous process. The boundaries between all the geological epochs are arbitrary, and are used merely as a convenience with the tacit admission that they cannot represent any specific moment in time.