Did you know there are two species of cormorant in the UK?

They are the cormorant and the shag and the names are used almost interchangeably. These goose-sized, long-necked water birds are so similar in appearance it is difficult to tell them apart.

They are large (up to 100cm long, wingspan 130-160cm) with brown/ black feathers. However, if you saw them side-by-side you would see that the shag has a longer and more slender beak and less yellow skin on its face.  Its forehead angle is steeper than a cormorant.

The breeding plumage differs in that an adult cormorant has a white patch on its thigh whereas the shag develops dark glossy green plumage and a prominent curved crest on the front of its head.

Cormorants can be found either on the coast or on inland waterways and are often seen in groups. Almost exclusively a coastal breeder, a tree-nesting colony of cormorants was found inland in Essex in 1981 and by 2012 this had increased to 89 inland sites in England. Their nests are primarily built of seaweed, reeds and twigs.

Shags live along the coast, but occasionally they hunt inland on rivers and lakes, and are usually solitary birds.

Both species eat fish and eels and are expert divers able to swim underwater for around 70 seconds. They have glands that secrete oil to keep their feathers waterproof, even so the birds can often be seen spreading their wings to dry them.

Protected by The Wildlife and Countryside Act 1981, the current status of cormorants and shags is green. When I worked at a local water company in the late-70s I can remember there being a bounty on cormorants’ heads (or beaks). Fishermen would bring bags of beaks into the office for a small reward. At the time I considered this a barbaric activity and refused to get involved despite the risk to my job, and was glad when the bounty ceased.

The population of cormorants has been kept at a low level due to persecution by humans and pesticide pollution.

Astonishingly cormorants can live up to 24 years in the wild, however, the mortality rate of juveniles is high. Around 40% of birds leaving the nest die in their first year.

According to the RSPB there are just over 9,000 breeding pairs, with 41,000 cormorants wintering in the UK.