Great cormorant

Lore & Background

The great cormorant was formally described in 1758 by Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae under the binomial name Pelecanus carbo. The type location was later restricted to the rock-nesting form of the north Atlantic Ocean by German ornithologist Ernst Hartert in 1920. It is now one of 12 species in the genus Phalacrocorax, introduced in 1760 by French zoologist Mathurin Jacques Brisson. The genus name derives from Latinized Ancient Greek for 'bald raven', and the specific epithet carbo is Latin for 'charcoal'.

Six subspecies are accepted, with an additional closely related species, the Japanese cormorant (Phalacrocorax capillatus), possibly embedded within P. carbo based on genetic evidence. The great cormorant is a large bird with considerable size variation across its range. Males are typically larger and heavier than females. The plumage is largely black with bronze to greenish iridescence on wings and tail, and purple iridescence on the body. Adults have striking deep sea-green eyes, a stout hooked bill, and fully webbed feet. In breeding season, adults develop white filoplume patches on thighs, head, and upper neck.

Reader's Guide

The great cormorant is a significant species both ecologically and in human history. It is a widespread and common bird, feeding primarily on fish caught by foot-propelled diving, with dives lasting 1–3 minutes to depths up to 9.5 meters. It nests colonially near wetlands, rivers, and sheltered inshore waters, building stick nests in trees, on cliff ledges, or on predator-free rocky islands. Clutches average three to five pale blue or green eggs, incubated for 28–31 days.

Its relationship with humans has been contentious. Many fishermen view it as a competitor for fish, leading to past hunting that nearly drove it to extinction. Conservation efforts allowed populations to recover, but increasing numbers have renewed conflicts with fisheries. In Britain, inland breeding has become more common, and some fish farms report high losses. Licensed culling is permitted in the UK under specific circumstances. The species is also vulnerable to highly pathogenic avian influenza outbreaks, with mass mortality documented in Baltic Sea colonies. Cormorant fishing is practiced in China, Japan, and elsewhere, though the article does not detail this practice further.

Did You Know?

• The great cormorant is tied as the second largest extant cormorant species after the flightless cormorant.
• The species has 14 tail feathers, unlike the European shag and double-crested cormorant which have 12.
• About 60% of its dives are to the benthic zone, and its hearing may have evolved for underwater use.