The European Shag, also called the Common or Crested Shag and the Green Cormorant, has a crest/quiff and a metallic green tinge to its feathers in breeding plumage.
It lacks the yellow throat patch of the larger Great Cormorant but has some yellow where its slimmer beak meets its face.
The names Cormorant or Shag are sometimes interchangeable; in the past "Shag" was applied to a Cormorant with a crest (or double crest)
but currently is usually applied to small cormorant species.