Natural History in the Highlands and Islands. F. Darling Fraser

those subjects with which he is most familiar—the life histories of seals, deer and sea-birds, and the ecology of grazing and regeneration of forest growth. Nevertheless, he has a general view, derived from a wide and mature experience, tempered with homely wisdom, and illuminated by his genuine love for the Highlands. There is, in this book, no aura of bogus romance; there are no purple passages or sporting reminiscences: instead, he has given us something of the real essence of Scotland’s land and sea.

      THE EDITORS

       Every care has been taken by the Editors to ensure the scientific accuracy of factual statements in these volumes, but the sole responsibility for the interpretation of facts rests with the Authors

       AUTHOR’S PREFACE

      A MAN does not write a book like this one without a good deal of help. First, there is that host of observers and seekers after knowledge whose works have been scanned for their contribution to this attempted synthesis. Then there is the good criticism given by the Editors, James Fisher in particular, for his friendship has been sorely tried. Charles Elton was good enough to spend part of his first holiday in seven years reading the draft, and his suggestions have been invaluable. Averil Morley has helped me throughout in gathering data and as a constant kindly critic. I am grateful to them all, but would not like to unload on to them any of the responsibility for this book. After all, I have not always taken their advice and must stand or fall alone in what seems to me something of a tight-rope act. This work is not a handbook of natural history; that is why I have refused to call it The Natural History of the Highlands and Islands; that would have been too presumptuous a title. Whole orders of animals and plants escape any mention, partly for want of space but mainly, perhaps, because one man is not omniscient. The aim has been to tell a plain tale of a remarkable region and of some of the causes, interactions and consequences which confront the inquiring mind. One thing I would say: I know more now about natural history in the Highlands and Islands than when I began this book three years ago, and writing it has set me thinking. I want to get into the field again and look into new problems that have occurred to me. If the book has the same effect on anybody else, it will have served some good purpose.

      F. D.

      Strontian,

      North Argyll.

       CHAPTER 1

      GEOLOGY AND CLIMATE

      IT MAY be truly said of the Highlands and Islands of Scotland that the geology of the country makes the scenery. The geology cannot be ignored in describing the area, as the subject might be if the rocks were overlaid with a great thickness of soil deposited by alluvial drift. Here in the Highlands there is often no soil at all, the bare rocks starkly showing to sun and tempest; or again, a thin layer of acid peat may be the only covering. Such true soils as exist on the hillsides and in the straths are usually of fairly local origin, reflecting the qualities of the rocks near at hand.

      Geology, then, linked with climate, determines very largely the nature of the initial vegetation of the Highlands. Man himself determines the secondary vegetation to some extent through his management of animals and of fire, but there are decided limits to what he can do in the face of the geology. Vegetation in its turn, and again governed by climate, has a remarkable effect on the animal life of the region, both in variety and distribution. Geology, through the relief of the land to which it gives rise, also has a definite effect on climate—for example, the presence of mountains results in the condensation of the moisture of the air, hence the characteristic heavy rainfall in their vicinity. The vegetation influences slightly the immediate climate of a region, and the two together may have their effect on the superficial geology, as in woodlands preventing erosion and gullying of hillsides.

      We should remember the constant interplay of these dynamic forces as well as life itself in studying the natural history of the Highlands and Islands. It is a noble drama of weather and mountain and sea and plant and animal, the dramatis personae of which may be given this diagrammatic form:

      From almost every point of view of natural history, the Highland region of Scotland is demarcated by the sharp geological line known as The Highland Border Fault which runs north-east, south-west across Scotland from the mouth of the Clyde to Stonehaven. Although a good deal of Scotland’s best agricultural land lies along the east coast north of this line, the great mass of the country to the north-west of the Fault (also known in history as the Highland line) is mountainous. The word mountainous does not, however, allow us properly to speak of mountains in Scotland. It is rather an inverted boast of the Scot, secure in his country’s superiority of wild terrain, to inform the visitor that there are reputedly mountains in England and Wales and in Ireland, but in Scotland they are called hills.

      The Highlands, also, are not necessarily high ground. The highest point of the Hebridean island of Benbecula is only 420 feet, but Benbecula is unquestionably as Highland in its natural history as in its human cultural relationships.

      There is another major geological feature which plays a large part in the topography of the area, in the shape of the Great Glen of Scotland, a second big fault forming Glen Albyn (the English have an annoying habit of calling it the Caledonian Canal!). This great dividing line between the Northern and North-West Highlands on the one hand and the Central and South-West Highlands on the other is marked not only by the Great Glen itself, but by the chain of long freshwater lochs it contains, the most famous of which is Loch Ness, 21 ³/₄ miles long and of great depth. The loch drains north-eastwards to the short Ness River and the Moray Firth at Inverness. The very low watershed which crosses the Great Glen, in so far as the flow northeast or south-west is concerned, is above the head of Loch Oich and is no more than 115 feet above sea level. The next loch south-westwards is Loch Lochy, and the Lochy River which flows from it runs into the salt water of Loch Linnhe, which ultimately fans out after the Corran Narrows and becomes the Firth of Lorne which is such a distinctive feature of the western coastline. At the south-westward end of the Great Glen and at the head of Loch Linnhe stands the sentinel-like massif of Ben Nevis, the highest hill in Scotland, 4,406 feet high. The summit is only four miles from sea level as the crow flies, so the full sense of height of this mass can be appreciated by the traveller coming eastwards down Loch Eil. Ben Nevis is formed by a granite intrusion between the two great areas of the Moine and Dalriadan schists. It is a wide-topped hill of no particular beauty of shape, but its north corrie is undoubtedly impressive, for it contains the highest sheer cliff face in Britain of about 1,500 feet (Plate I) as well as one of the very few semi-permanent snow patches in Britain. This patch of snow is untouched by the sun’s rays.

      The actual summit of Ben Nevis is not of the granite rock of which the main mass of the hill is composed. The summit is the top of a gigantic cylinder of tertiary basalt. Presumably this volcano originally spread the basalt over the whole of the hill, but all except the protected summit has been eroded away.

      It is worth noting that the two highest mountainous groups in Scotland are formed of granite—Ben Nevis, and the Cairngorm region, 4,296 feet, east of the Spey; and east again, there is Lochnagar, on the eastern side of the Highland area, also granite and reaching 3,760 feet. The Cairngorms are of much greater extent than the Ben Nevis massif and, partly because of their considerable alpine plateaux at about the 4,000-foot contour, have a special place in Highland natural history. Topographically, the Cairngorms viewed from afar may seem as uninteresting as Ben Nevis, but the physical beauty of these hills is for intimate observation in the magnificent corries and on the high plateaux. It is possible to walk a pony on to these high ridges and plateaux without any trouble, the ground being good all the way.

      There are two more striking geological phenomena which will be less obvious to the casual observer than those of the Highland Boundary Fault and the Great Glen. First, that definite line of tectonic