From the distant cliffs of Unst in the north of the Shetland Islands to the muddy creeks of Rockcliffe in the Solway Firth, The National Trust for Scotland owns some 20 properties around the coast of Scotland.
Of these, St Kilda NNR is undoubtedly the foremost, being the largest seabird colony in the North-east Atlantic with around a million seabirds. Mingulay, Canna and Fair Isle are other island properties that are internationally important for their seabirds, while St Abbs NNR is one of the most readily accessible colonies on the mainland. Trust properties on Unst and Fetlar fall within the Hermaness and Fetlar Special Protection Areas, while the Trust’s Mains of Dun farm at Montrose Basin Local Nature Reserve holds one of the largest colonies of Eider Ducks in Scotland.
Less well known, the Murray’s Isles, off Gatehouse of Fleet, are nonetheless regionally important for their colonies of gulls and cormorants while Iona and Staffa are best known for other aspects of their cultural heritage. Staffa NNR, though visited mainly for the spectacular Fingall’s Cave, is one of the easiest places to see and photograph puffins.
On the mainland, Torridon and Kintail are famous for their high mountains, but Balmacara has a complex coastline from Plockton to Kyle of Lochalsh that includes a number of small islands used by seabirds and otters alike.
Typically a species of northern and western coasts, the largest colony in Scotland is at Mingulay and Berneray with some 10% of the EU population.
Other large colonies are to be found at Fair Isle, Caithness and Handa Island. While normally nesting in crevices scattered amongst other seabirds, a single cliff face at the west end of Berneray is home to almost 5000 pairs. Predation by brown rats (at Canna) and American Mink at other sites is known to have reduced numbers.
Food: Dives normally to 2-3 m but can dive deeper. Chiefly fish (sand eels) with some invertebrates. Submersion not more than 22 s (maximum 40-52 s).
Nest Site: Rock ledges and crevices beneath rock overhang; sometimes uses old rabbit or puffin burrow.
Breeding: Mid April to mid June where 1 egg is laid and very rarely 2.
Wintering: Northern populations are mainly migratory. Scottish population south west Norway where they feed and moult, Bay of Biscay, Morocco and western Mediterranean.
Distribution: Mainly west coast of the UK, Southern Ireland, Iceland, Faeroes, Bear Island, Jan Mayen, France, Norway, Sweden, Finland, Russia.
Although it is a common sight around Scotland, estimating the breeding population of European Shags is difficult because of their habit of nesting under boulders and in dark, inaccessible caves.
One of the largest colonies in the UK was on Canna, though it has declined recently due to predation by rats. Other large NTS colonies are to be found at Fair Isle, St Abbs and Mingulay.
Food: Mainly fish, sometimes swallowing prey before reaching the surface. Mainly surface diver but can also plunge dive, staying under for up to 3-4 minutes.
Nest Site: Prefers more sheltered and shady overhung sites to that of cormorant on ledges, fissures, caves and under boulders. Nest material heap of vegetation such as bracken, seaweed, using grasses for finer lining
Breeding: Mid March to mid June where 1-6 eggs are laid.
Wintering: Scottish population move north to Norway and other UK populations move Irish Sea, Bristol Channel, and south to Brittany.
Distribution: UK, southern Ireland, Norway, Russia, Iceland, Faeroes, Spain and southern Europe.
Almost a sixth of the world’s population and 36% of Scotland’s population breeds on St Kilda, though numbers are growing at other colonies, such as the Bass Rock.
The only other colony on NTS property is at Fair Isle.
Food: Mainly fish, caught by diving from heights of 10-40 m and staying under from 5 – 20 s.
Nest Site: On ledges of cliffs, sea stacks where nests are evenly spaced but never touching (60-80 cm apart). : Large compact pile of seaweed, grass, feathers and earth all cemented on a substrate of excreta.
Breeding: Mid April to mid May where one egg is laid.
Wintering: Go south to sub-tropical waters sometimes into tropical waters off the coast of west Africa.
Distribution: UK, Ireland, Faeroes, Iceland and Norway.
Not common on NTS properties. Small numbers breed on the islands around Iona
Food: Terrestrial and aquatic invertebrates, fish taken by direct predation of food piracy or scavenging.
Nest Site: On small inshore rocky stacks, islets, islands, grass and rocky slopes and cliff ledges, shingle banks and sand dunes. Sites also near lochs, shingle bars, islets, pools, lochans, bogs, grassy and heather moorlands and on open ground. Nest shallow cupped structure of vegetation or seaweed.
Breeding: Mid May to mid June where 3 eggs are laid.
Wintering: Scottish birds mostly winter in the Irish Sea and Ireland.
Distribution: Scotland, western Ireland, Iceland, Faeroes, Norway and Russia, Sweden, Finland.
Seabirds are such a common feature of any visit to Scotland’s beautiful coast that we become blasé about them. Yet they are one of our national specialities.
Scotland is home to some 70% of all of the seabirds in the UK and the UK is home to almost a third of all of the seabirds in the European Union. For species such as the Great Skua, the Atlantic Puffin and the Northern Gannet, we hold the bulk of the world population.
The gannet’s plunge into the unfamiliar twilight of the marine environment reminds us that, though they may need rocks to nest on, they depend on the sea for their sustenance, and that the extraordinary richness Scotland’s bird colonies reflects the productivity of the surrounding seas. Seabirds are only the visible tip of the iceberg of the vast marine ecosystem.
Marine life is strongly influenced by ocean currents, which bring nutrients to refresh the surface waters exhausted by the continual effort of rearing crops of floating algae. The North-east Atlantic plays a key role in the global pattern of ocean circulation, at the pinch point where the northward-flowing North Atlantic Drift is replaced at depth by cold waters pouring out of the Arctic basin. For this reason it is one of the world’s most productive seas, sustaining a teeming broth of algae, invertebrates, fish, marine mammals and ultimately seabirds.
While, on land, climate change is measured in tenths of a degree, the sea surface temperature in the southern North Sea has risen by some 2C in the last 20 years. This has had a dramatic effect on the timing of appearance of the different species plankton, a complex choreography formerly perfectly timed to provide the food needed for the seabirds’ breeding seasons. There is increasing evidence that the alarming breeding failures of seabirds in Shetland and Orkney in 2003 and 2004 are the first signs of our impact on the world’s climate.
Stock assessments carried out in 2005 have shown that sandeels in the North Sea are at half the minimum level needed to sustain a fishery. This has prompted the European Commission to propose a total closure of the fishery.
The breeding failures of seabirds seen along the North Sea coast of Scotland in 2004 were thought largely to have been caused by a shortage of sandeels, on which many species feed, and it is feared that the pathetically low levels recorded in 2005 bode ill for the current breeding season.
Research carried out by staff from the Centre for Ecology and Hydrology on the Isle of May has shown that sandeel numbers are adversely affected by rising sea temperatures as well as the industrial fishery. In combination, they are likely to lead to a very steep decline in sandeels and the species of seabirds that depend on them. Sea surface temperatures in the Southern North Sea have risen by 2C over the last 25 years and even the temperature at the sea bed, normally more stable, has risen by 1.5C since the 1970s.
Yearling sandeels are in particularly short supply after a warm winter and this period is critical in determining the success of seabirds as they are preparing to breed. Sandeel numbers, in turn, are believed to be linked to the abundance of the microscopic plankton on which they themselves feed.
Seabirds, such as terns and kittiwakes which feed mainly on sandeels, are particularly badly affected, though even guilemots and puffins, which can access other fish prey through deeper diving, are beginning to show signs of breeding failure.