Great Cormorant

What Is a Great Cormorant?

The great cormorant (Phalacrocorax carbo) is a large, fish-eating water bird found across much of the world. It belongs to the cormorant family and is known for its dark plumage, long neck, and habit of perching with its wings spread wide to dry after diving. It is one of the most widespread cormorant species on Earth.

Appearance and Identification

Adults are mostly glossy black, often with a greenish or bluish sheen, and have a distinctive white patch on the throat and cheeks. During the breeding season, many individuals develop white thigh patches and fine white plumes on the head and neck. The bill is long and strongly hooked at the tip, and bare skin at the base of the bill is typically yellow. The feet are webbed and set well back on the body, an adaptation for powerful underwater swimming. Juveniles are duller and browner, often with pale or whitish underparts. Great cormorants are noticeably larger than most related species, which helps distinguish them where their ranges overlap.

Habitat and Range

Great cormorants occupy an unusually broad range of aquatic habitats. They are equally at home along rocky and sandy coasts, in estuaries and sheltered bays, and on inland freshwater bodies such as lakes, large rivers, and reservoirs. This flexibility has allowed the species to colonize much of Europe, Asia, Africa, and Australia, along with parts of eastern North America and Greenland. Some populations are resident year-round, while northern breeders migrate south to avoid frozen waters in winter. They generally need open water for feeding and secure perches or trees near the shore for roosting and nesting.

Diet

The great cormorant is a carnivore that feeds almost entirely on fish. It hunts by diving from the surface and pursuing prey underwater, using its webbed feet for propulsion and its hooked bill to seize slippery targets. A wide variety of fish species are taken, and the birds tend to catch whatever is locally abundant, from eels and flatfish in coastal waters to roach, perch, and other freshwater species inland. Occasionally they also eat crustaceans and amphibians. Because they can consume substantial quantities of fish, great cormorants sometimes come into conflict with commercial and recreational fisheries.

Behavior

Cormorants are often seen standing on rocks, posts, or branches holding their wings outstretched. Their feathers are not fully waterproof, an unusual trait among water birds, so this wing-spreading posture helps them dry off and may aid digestion by warming the body. Reduced waterproofing lowers buoyancy and makes diving more efficient. Great cormorants are strong fliers and frequently travel in loose lines or V-formations between roosting and feeding sites. They are social outside the breeding season, gathering in communal roosts, and can be quite vocal at colonies with guttural croaking calls.

Life Cycle and Reproduction

Great cormorants breed in colonies, sometimes alongside other water birds. Nests are bulky structures of sticks, seaweed, and other vegetation, built on cliff ledges, in trees, or on the ground on islands. A typical clutch contains around three to five pale eggs, which both parents incubate for roughly four weeks. The chicks hatch naked and helpless and are fed by both adults, fledging after several weeks but often remaining dependent for a time afterward. Birds generally begin breeding at a few years of age. In the wild, great cormorants commonly live around 11 to 15 years, though some individuals survive considerably longer.

Conservation Status

The great cormorant is listed as Least Concern by the IUCN, reflecting its very large and generally stable or increasing global population. In many regions numbers have recovered strongly after historical persecution and habitat loss. This success has led to localized tension with fishery interests, and some areas manage cormorant numbers to reduce perceived impacts on fish stocks. Overall, however, the species faces no major range-wide threats and remains one of the most successful and adaptable of the world’s water birds.

Frequently Asked Questions

Why do cormorants spread their wings? Their plumage is not fully waterproof, so after diving they perch with wings open to dry their feathers and warm up.

What do great cormorants eat? They feed mainly on fish, catching a wide range of species by diving and pursuing prey underwater.

Are great cormorants endangered? No. They are listed as Least Concern, with a large and widespread population across multiple continents.