Phalacrocoracidae is a family of around 40 species of aquatic birds known as cormorants and shags. In 2021, the International Ornithologists’ Union recognized seven genera within this family. The great cormorant (Phalacrocorax carbo) and the common shag (Gulosus aristotelis) are the primary species found in Britain and Ireland.
Cormorants and shags are medium-to-large birds, typically weighing between 0.35–5 kg and with wingspans of 60–100 cm. They possess a long, thin, hooked bill and webbed feet for diving. Excellent divers, they can reach depths of up to 45 meters and primarily feed on fish and small eels. Nesting occurs in colonies along coasts or inland waters, and they are known for their distinctive wing-drying behavior after fishing.
Most species have dark plumage, with some Southern Hemisphere varieties being black and white or colorful. Cormorants lay chalky-blue eggs and typically have one brood per year, with parents regurgitating food to nourish their young.
