Cormorant
Fish-eating diving birds with webbed feet and hooked bills.
Cormorants and shags belong to the family Phalacrocoracidae, which includes about 40 species of aquatic birds found globally, with the exception of the central Pacific islands. The common names "cormorant" and "shag" are applied somewhat haphazardly across species, with no consistent biological distinction. In Britain and Ireland, only two species are regularly seen: the great cormorant and the common shag. The term "cormorant" likely derives from the Latin *corvus marinus*, meaning "sea raven," a mistaken association with corvids that persisted into the 16th century. "Shag" refers to the bird's crest, which is prominent in the European shag but less so in the great cormorant. In some regions, such as New Zealand, all local members of the family are called shags, even if the same species is known as a cormorant elsewhere.
These birds are medium to large, with body weights ranging from 0.35 to 5 kilograms and wingspans of 60 to 100 centimeters. Most species have dark feathers, though some Southern Hemisphere species are black and white or colorful. They have long, thin, hooked bills and webbing between all four toes. All species are fish-eaters, catching prey by diving from the surface. Underwater, they propel themselves with their feet, sometimes aided by their wings, and some species can dive as deep as 45 meters. Their wings are relatively short, making underwater movement efficient but resulting in among the highest flight costs of any flying bird.
Cormorants nest colonially on seacoasts, in trees, on islets, or cliffs. They are coastal rather than oceanic, though some have colonized inland waters. After fishing, they often stand with wings spread, a behavior widely believed to dry their feathers, though other functions like thermoregulation have been suggested. The family may have originated from a freshwater ancestor in south Asia, with offspring adapting over time and spreading across Eurasia and the world.
- Common names
- Cormorant and shag
- Family
- Phalacrocoracidae
- Number of species
- Approximately 40
- Body weight range
- 0.35–5 kilograms (0.77–11.02 lb)
- Wing span range
- 60–100 centimetres (24–39 in)
- Primary diet
- Fish
- Notable feature
- Webbing between all four toes
Lore & Background
The name 'cormorant' likely derives from Latin 'corvus marinus', meaning 'sea raven', reflecting a historical mistaken belief that they were related to ravens. The terms 'cormorant' and 'shag' were originally applied to the two British and Irish species, with 'shag' referring to the bird's crest. As explorers encountered other species, the names were assigned haphazardly, sometimes varying by region; for example, all species in New Zealand are called shags, even those known as cormorants elsewhere. Cormorants and shags are medium-to-large aquatic birds with dark feathers in most Northern Hemisphere species, though many Southern Hemisphere species are black and white or even colourful. Their long, thin, hooked bills and webbing between all four toes are defining features. They range worldwide except for central Pacific islands, inhabiting seacoasts, trees, islets, cliffs, and some inland waters. These fish-eaters dive from the surface, propelling themselves underwater with their feet and sometimes wings, and some species dive to considerable depths. Their relatively short wings, adapted for efficient underwater movement, result in high flight costs. After fishing, they often stand with wings spread, a behaviour linked to drying feathers, thermoregulation, or other functions. All species possess preen gland secretions that help maintain feather condition.
Reader's Guide
Cormorants and shags are significant as widespread, adaptable fish-eating birds that inhabit coastal and inland waters globally, except for the central Pacific islands. Their unique adaptations include webbing between all four toes, a long hooked bill, and relatively short wings that enable efficient underwater propulsion but result in high flight costs. Cormorants are colonial nesters on seacoasts, trees, islets, or cliffs, and their eggs are chalky-blue. The spread-wing posture often seen after fishing is widely believed to aid in drying plumage, though other functions have been suggested. Their evolutionary history may trace back to a freshwater ancestor in south Asia.
Did You Know?
- The great cormorant and common shag are the only two species of the family commonly encountered in Britain and Ireland.
- Cormorants have webbing between all four toes, a feature shared with their relatives.
- The name 'cormorant' is a contraction probably derived from Latin 'corvus marinus', meaning 'sea raven'.
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