Hebridean Coastline
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Geology & Wildlife

Coastal Geology

The Western Isles is a long chain of islands running roughly north to south.  There are over 100 islands of all shapes and sizes, which make up a land area of some 305,000 ha.  The islands have an extensive coastline, approximately 2,500km in length, and there are many sea lochs, bays and inlets. Lewis and the southern island chain comprising the Uists, Benbecula and Barra are relatively flat, covered by lochs and peat bog. The coast is typically rocky in the east, but with long white sandy shell beaches in the west. It is these western coasts that are most at risk of erosion, due to the soft, sandy, low-lying nature of the extensive coastal area


Throughout the Western Isles, there are many areas where diversity of wildlife and habitat are evident, including four National Nature Reserves; the uninhabited islands of North Rona and Sgula Sgeir, the island of St Kilda, the Monach Isles, and Loch Druidibeg.
The uninhabited islands of North Rona and Sgula Sgeir annually support and estimated 130,000 breeding seabirds with 15 different species including storm petrels, guillemots, razorbills, gannets and puffins.
St Kilda has countless remarkable natural qualities. It is the most important seabird breeding station in North West Europe with over 1 million birds. These include the world’s largest colony of gannets (60,000 pairs) and Britain’s largest colony of Puffins (140,000 pairs).
The Monach Isles National Nature Reserve is an isolated piece of machair land just off North Uist, on whose beaches around 10% of the world’s population of grey seals gather every autumn.
Loch Druidibeg National Nature Reserve is one of the best examples in the Western Isles of the transition from the western coastal machair system to the inland acid moorland and blanket bog.
Not only are birds such as lapwings, redshank, oystercatcher, snipe and corn buntings to be found on the island machair land in abundance, around a quarter to a third of all of Britain’s breeding dunlin and ringed plover occur on the machair, nesting at the highest densities recorded anywhere in the world. The corncrake, one of Britain’s most vulnerable birds which has disappeared from almost everywhere within the United kingdom except the Scottish islands, has shown a modest recovery in numbers in some parts of the Western Isles. Its call is still a familiar sound on many crofts in the summer. Eagles too are a popular feature of island wildlife. The mountains of north Harris in particular are important for golden eagles, while occasional sightings of the larger white-tailed sea eagle, reintroduced to Scotland in 1975, have been reported.