Cormorant (family Phalacrocoracidae)

BirdDivingFish-Eater

Overview

Cormorants are medium to large waterbirds with long bodies, long necks, hooked bills and, in most species, dark plumage. They are pursuit divers: rather than plunging from the air, they swim down from the surface and chase fish underwater using powerful webbed feet.

Their best-known habit is standing with wings held open after a dive. Unlike most waterbirds, cormorant plumage is only partly water-repellent and becomes wet during diving. The usual explanation is that a wettable plumage reduces buoyancy and makes underwater pursuit easier, at the cost of having to dry out afterwards.

The great cormorant (Phalacrocorax carbo) is used here as a familiar reference species; the family includes around forty species worldwide, among them the birds called shags.

Habitat & Range

Cormorants occur on coasts, estuaries, lakes, rivers and reservoirs across most of the world, missing only from the most extreme environments. They need water clear enough to hunt in by sight and safe places to roost and nest — cliffs, trees, islands and artificial structures. Colonies are often large and conspicuous, and the guano beneath them can kill the vegetation they nest in.

Diet

Cormorants are almost entirely fish-eaters, taking whatever species are locally abundant, along with some crustaceans, eels and amphibians. Prey is caught in underwater pursuit and usually brought to the surface to be manoeuvred and swallowed head first. All four toes are joined by webbing, giving powerful propulsion.

Behavior

Cormorants dive from the surface, often with a small forward leap, and swim underwater with the feet. Between dives they return to a perch and adopt the characteristic spread-wing posture. They are colonial nesters and often roost communally. Many species are strong fliers that commute considerable distances between roosts and feeding areas, flying low over water in lines or loose V formations.

Human Interaction & Conservation

Cormorants have a long and contested relationship with fisheries: they are efficient fish-eaters, and conflicts with anglers and aquaculture recur wherever their populations are healthy, sometimes leading to control programmes. In parts of East Asia, cormorants have traditionally been used by people to catch fish — a practice now largely maintained for heritage and tourism. Some island and coastal species are highly restricted and threatened. This profile offers no wildlife-control guidance; status varies sharply by species, so verify at the IUCN Red List.