Spot the Common Shag

The common shag (Phalacrocorax aristotelis) is one of the cormorants of the order Suliformes. In Iceland, two other species, the great cormorant (Phalacrocorax carbo) and the queen of the sea, the northern gannet (Morus bassanus) belong to the order. A characteristic of these species is having a web between all four toes and a throat sac where they retain food, which they later vomit half-digested to their young. There are three subspecies of the common shag in the world, but the Icelandic one (P. a. aristotelis) is also found in west- and south Europe all the way south to the Iberian peninsula.

The „Sea-Raven“ Is Not Actually Black

From a distance, the common shag looks black and has therefore been called „the sea-raven“ among fishermen. A greenish glow is visible on the dark feather plumage when one looks at adults.  The skin at the base of the bill is yellow, and the eyes are green. From January until spring, the shag has a beautiful crest on its forehead, which disappears in May. The sexes look the same, but juveniles have brown eyes and dark brown plumage. Shags are medium-sized birds. The length is 63-81 centimetres (25-32 in), the wingspan is 89-106 centimetres (35-42 in) and the weight is about 1,984 grams (70 oz).

Experience Wildlife and Nature in One Place

Perlan stands as Reykjavik's iconic Nature Exploratorium, offering immersive learning about Icelandic nature. Explore various exhibitions like, a real ice cave, engage with hands-on exhibits, witness a life-size bird cliff, and enjoy a volcanic show. The Planetarium dome theatre showcases virtual northern lights. Additionally, the Icelandic Museum of Natural History presents a hands-on exhibition at Perlan, unravelling the mysteries of water in Icelandic nature. Read more about Perlan’s different exhibitions here. 

Monogamous Mating, Nesting Habits, and Parental Care

Shags are monogamous, mating for one year at a time. Sometimes, the pairs renew their relationship the following year, but not always. The shag lays eggs, like other cormorants, early in spring and is often fully nested in the middle of April. The eggs are  3-5 light bluish-coloured,  each weighing about 51 grams or 1.8 oz. The nest is a heap made from seaweed and other things from the surroundings, glued together with bird droppings. The young hatch are blind and featherless, totally dependent on their parents for survival, and this is one of the characteristics of the Suliformes.

What Do They Eat?

Cormorants are great divers, and the shag is no exception. The feet are situated far back on the body, and the webbing between all four toes makes it a good oar for diving. The shag is almost entirely observed at sea and is an opportunist when feeding. During the breeding season, it feeds mostly on sand eels (Ammodytes marinus), shorthorn sculpin (Myoxocephalus scorpius), herring (Clupea harengus), saithe (Pollachius virens), cod (Gadus morhua) and even crustaceans and bivalves.

Distribution and Population Size 

The shag is a stationary bird in Iceland mostly observed on the west side of the country. The main breeding areas are low islands, islets and skerries in Breiðafjörður and Faxaflói. Breeding distribution has recently expanded towards Northwest Iceland. During winter, the shags are observed from the southwest to the northern part of the country. In  2010 a shag bred for the first time off the east coast of Iceland, in Papey and  10 years later on the island Skrúður. Despite the expansion of the distribution, the shag population size has decreased. In  1994, it was estimated that there were 6939 breeding pairs, but only 4745 in 2019.

Shags „Preach“ After a Good Bath

Shags are often seen standing on rocks and skerries waving their wings for a long period. This activity has been called „preaching“. Both shag and the cormorant perform this strange act for an unknown reason. Maybe they are drying their feathers after diving. This unexplained behaviour might also help with digestion as the birds are extremely greedy, stuffing their stomachs with large fish. It is also possible that they are warming up after a cold dive in the sea.

Shags Have Been Hunted for Centuries

The young stay in the nest during the summer and do not leave the colony until they start to flutter around and fly. They are fat, tasty and easy prey for humans. Icelanders have hunted flightless shags for centuries by surrounding the colony armed with clubs. The juveniles were clubbed and used for human consumption, as feathers and meat were utilised. Even eggs were collected and eaten. This unethical hunting method has now mostly been abandoned. The shag is, however, still hunted in Iceland, as 1500-2000 birds are shot and eaten each year.

Five Fun Facts About the Common Shag

1. The shag´s nesting territory is only the nest pile and a narrow strip around it, resulting in a dense colony where the birds have their own little private spot.
2. The oldest known shag was hunted in Britain, 30 years and 7 months old. The average lifespan is about 15 years.
3. Shags are great divers and can dive down to 45 metres or 150ft.
4. The Icelandic word „skarfur“ has a negative meaning and is used for a person who is rude, greedy and in general boring.  
5. A „skarfabæli“ is a word used for the shags nest, but in Icelandic, it also means a filthy habitat smelling badly.