Marine Ducks & Seabirds

IN addition to the numerous wildfowl and waders supported by the shore, estuarine and freshwater coastal environments already mentioned in the text, Ireland's seas and coasts provide habitats for regionally and internationally important numbers of marine ducks and seabirds, which may be resident, summer or winter visitors, or else passage migrants. They include:

Ducks

The mallard is both a freshwater and marine species that may be seen resting on the open sea. The long-tailed duck is essentially a marine bird, often seen well out to sea even in rough weather. The red-breasted merganser is a resident that is commonly seen on coastal waters in winter, diving for fish and invertebrates, along with winter visiting goldeneye. Scaup is a predominantly marine species, while eider and common scoter are exclusively marine. Eiders are residents, breeding on the north and northwest coasts of Ireland where they feed by diving for mussels and other molluscs. Common scoter feed by diving for crustaceans, cockles, mussels, larvae and benthic worms; though principally a winter visitor, they may be seen offshore year-round, and a few birds breed on the Irish coast. Less common is the winter-visiting velvet scoter.

Divers and grebes

The great northern diver and red-throated diver are common winter visitors to Irish coastlines, while the black-throated diver is a much more rare winter visitor. All are found on open coastal waters, bays and sometimes harbours, where they dive for fish and marine invertebrates. In winter, great crested grebes may also be found in open coastal waters and harbours, as well as the less common Slavonian grebe.

Gulls

The herring, common, great black-backed, lesser black-backed and black-headed gulls are resident breeding birds of sea and coast, as is the kittiwake. Other gulls found around Ireland's coasts are the uncommon winter visiting Mediterranean, glaucous, Iceland and little gulls. Occasionally, the mainly pelagic Sabine's gull is blown inshore during its migration to/from the high Arctic regions of Canada, Greenland and Spitzbergen. Gulls generally feed on a wide range of food including fish, molluscs, worms, crustaceans, offal and carrion.

Fulmar, shearwaters and petrels

The fulmar is a member of the family that includes the mainly southern hemisphere albatrosses. It breeds on all suitable cliffs around Ireland's coast and is otherwise strictly pelagic, often following fishing vessels to feed on offal, though it principally feeds on a variety of fish, molluscs and crustaceans.

Four species of shearwaters (sooty, great, Mediterranean and Manx) are visitors to Irish waters in late summer-early autumn. Sooty and great shearwaters are birds of the open ocean, where they feed on a wide range of marine life including fish, squid, molluscs, crustaceans and offal from trawlers. Both species breed in the southern hemisphere. The Mediterranean shearwater breeds in the western Mediterranean. The Manx shearwater is a common, but infrequently seen, seabird which travels long distances to feed far out at sea on small fish, molluscs and offal. They only come ashore during the breeding season to nest in burrows, mainly on offshore islands. Birds arrive and leave the burrow in the dark to avoid predation by gulls. There are several important breeding colonies scattered around the Irish coast.

Petrels occurring around Ireland are the tiny storm petrel, a strictly sea-going bird which feeds on small fish and plankton, that comes ashore only to breed; and Leach's petrel, which breeds on some remote islands off the west coast.

Skuas

Sightings of piratical and predatory skuas (Arctic, long-tailed, pomarine and great skua), which are spring and autumn passage migrants off Ireland's coasts, usually only occur during onshore gales. All but the long-tailed skua feed by chasing and harassing gulls and terns, pursuing them until they drop or disgorge their food, though they will also variously feed on fish, small mammals, birds and eggs, carrion and offal.

Auks

The razorbill, guillemot, black guillemot and puffin are some of the most familiar seabirds around Ireland's coasts. Razorbills nest in close association with guillemots on cliffs and stacks, with foraging and resting birds sometimes forming large "rafts" on the sea. Outside the breeding season they disperse out at sea where they over-winter. Razorbills and guillemots feed on a wide variety of prey including fish, worms, molluscs and crustaceans by diving (swimming underwater by flapping the wings).

Usually seen at sea or resting on rocks, the black guillemot breeds in small groups around Ireland's coasts and offshore islands, nesting under boulders and in caves, holes and crevices. The puffin breeds in grassy cliff top (rabbit and shearwater) burrows in places scattered around Ireland's coasts. Puffins feed on a wide variety of marine prey, with sand eels forming an important part of the diet especially during the breeding season. During winter, which is spent far out at sea, the puffin's bill changes shape and dulls in colour. The little auk, which also winters at sea, is occasionally seen, usually only when blown inshore by gales.

Terns

The common, Arctic, roseate, little and Sandwich terns are summer visitors to Ireland's coasts, where they breed. They feed for fish by plunge-diving after a mid-air hover; Arctic, Sandwich and little terns also feed on marine invertebrates. The rarest of these is the roseate tern. The largest and most successful roseate tern breeding colony in Europe, and the centre of the Irish Sea population, is on the tiny island of Rockabill off County Dublin, where the terns nest in the shelter of tree mallow and other dense vegetation such as lyme grass. The arctic tern is an impressive long-distance migrant. Ireland is near the limit of its world breeding distribution.

The little tern is relatively scarce. After migrating from its African wintering grounds in spring, it prefers to nest in small colonies at a few traditional mainland sites on the east coast such as Baltray Dunes, County Louth, Kilcoole Beach, County Wicklow and Raven Point, County Wexford. On the west coast there are little tern colonies on offshore islands such as the Aran Islands, County Galway, and the Inishkea Islands, County Mayo. Their main habitat requirements are a shingle beach that is relatively free from human disturbance and close proximity to shallow coastal water or a lagoon for fishing.

Gannet

The gannet is Europe's largest seabird. It is almost always airborne, resting on the water only briefly after feeding on fish, which it does by plunge-diving from up to 30m high with half-folded wings. Gannets breed in colonies on cliffs and stacks, mainly on offshore islands. In summer the island cliffs of the Skellig Rocks off County Kerry are home to one of Europe's largest gannet colonies. Over 22,000 pairs of gannets nest on the Little Skellig while razorbills and guillemots nest on the Great Skellig Rock. The Great Saltee island off County Wexford also has an important gannet colony, with about 1,200 pairs of gannets breeding on the rugged southern cliffs. Situated in the southeast, the Great Saltee is also an important first landfall for spring migrants such as swallows arriving from their African wintering grounds. There are other gannet colonies on the Bull Rock in County Cork, and on Clare Island in County Mayo. The most recently established gannet colony, where the first breeding pairs arrived in 1989, is on a sea stack off Ireland's Eye close to the fishing port of Howth, County Dublin. In autumn gannets migrate (en masse, in strings of several birds, often visible from headlands) to warmer southern seas to over-winter.

Cormorant and shag

The cormorant and the shag are common residents around Ireland's coasts. The shag is normally a strictly marine species, frequenting open water off rocky coasts rather than the more sheltered waters and estuaries frequented by the cormorant. Shags breed colonially on rocks and in sea caves, and some birds disperse along the coasts in winter. The cormorant, also a colonial nester, breeds on rocks on the coast and trees inland. Though its coastal distribution is similar to the shag, cormorants are increasingly common on inland rivers and lakes. Both feed on a variety of fish, jumping clear of the water before diving.

Breeding seabird numbers

Ireland has 22 species of breeding seabird, including nearly 220,000 auks and at least 224,000 pairs of other species. This total does not include the huge, but virtually unknown numbers of storm petrels which nest unseen in burrows and crevices in at least 28 colonies around the Irish coast. On the four outermost Blasket Islands off County Kerry, storm petrels nest in the tens of thousands among the precipitous scree slopes, from sea level to the summits. The Irish colonies of Manx shearwater, storm petrel and gannet make up a sizeable part of the European populations of these birds.

Seabird lifespan

Recent evidence suggests that some seabirds may naturally live long lives. British Trust for Ornithology reports on the recovery of ringed birds show a number of longevity records for waders and seabirds, including 18 years for the ringed plover, 26 years for the bar-tailed godwit and 33 years for the common tern. Storm petrels have been shown to live to at least 32 years, Manx shearwaters to 35 years, gannets to 36 years and fulmars to nearly 41 years.

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