The European Shag is a species of Cormorant which breeds round the rocky coasts of western and southern Europe and is a familiar sight on the Pembrokeshire coast.
A goose-sized, dark, long-necked seabird, it is generally similar to the larger and more numerous cormorant, although in the breeding season it develops a glossy almost irridescent green plumage which gives it its alternative name of Green Cormorant. A prominent forward-facing crest also distinguishes it from the cormorant as also does the fact that it does not stray far from its nesting site and, unlike the cormorant, seldom ventures inland, although some appear to have been bucking the trend in the last few years, having been spotted on reservoirs and in estuaries. While the cormorant has a white chin and white underside, the shag is dark all over. Cormorants, of course, can be seen on rivers and estuaries far inland and even in town and city centres, diving and fishing in the freshwater streams and rivers. Shags, on the other hand, prefer the turbulent waters around the rocks and caves, often seeming to risk their lives in rough weather.
Visitors to the Pembrokeshire bird sanctuary islands of Skomer and Skokholm are certain to see shags on their cliff nesting sites. Some 27,000 pairs breed in the UK and an estimated 110,000 winter in this country, with large colonies on the Scottish coasts of Shetland, Orkney, the Inner Hebrides and the Firth of Forth. They are also common around the coasts of Devon and Cornwall, which have great similarities with Pembrokeshire.
Like the cormorant the shag nests on wide cliff ledges or in caves, with just a crude, untidy heap of grass, sticks and seaweed, often cemented down with its own guano, on which to lay its three or four eggs, producing only one brood, usually in May. Shags normally find their prey of fish, sand-eels and molluscs and crustaceans on the seabed, where they remain submerged for between 30 and 45 seconds, increasing their angle of dive with a characteristic little leap into the air before submerging. The chicks are hatched without any down, so they rely totally on the parent bird for their warmth, often staying in the nest for over a month before they can fly. Shags are found on Skomer, Skokholm and Grassholm as well as on the smaller rocks and islets scattered round the coast. They particularly like caves. and the naturalist and author Ronald Lockley recorded three or four pairs nesting high up on ledges in the darkness in a deep cave called The Lantern at the east end of Skomer, through which the tides flow from south to north at high water. Visitors like to see the shags and cormorants drying their wings in the sun after a session of fishing. They stand erect, their wings spread like dark crucifixes, looking very dramatic and ornamental and doing a very good impression of the Cristo Redentor presiding over Rio de Janeiro.