← Back to Fauna
Birds

Great Cormorant

Phalacrocorax carbo

Great Cormorant

General Overview

**THE BIGGEST AND MOST COMMON CORMON IN ROMANIA!** Spectacular aquatic bird, **MASTER OF UNDERWATER FISHING**, with **SHINING BLACK** plumage with copper reflections, long neck, strong hooked beak, green eyes. **Continental subspecies** *Phalacrocorax carbo sinensis* in Romania. **VERY Abundant in the Danube Delta**: 12,000-20,000 breeding pairs (90% of the national population!). **Global distribution** - present on 5 continents (except Antarctica and South America). **EXCEPTIONAL FISHING**: Dives up to 45 meters deep, stays under water for up to **70 seconds**, hunts in coordinated groups of **up to 500 individuals**! Often together with common pelicans forming "mixed fishing schools"! **Eats Fish**: Carp, Carp, Redfish, Sun Perch - Can catch fish up to 1kg! **Cannot swallow fish >20cm**. **Characteristic behavior**: After fishing **DRIES HIS FEATHERS** standing upright with open wings on poles, branches, stilts - iconic image! Feathers NOT fully waterproof (facilitates submersion) - requires regular drying. **COLONIAL** nesting in early spring in mixed colonies with little cormorants, herons, egrets. **"THE NATURAL BAROMETER OF THE DANUBE"** - fishermen follow it for schools of fish! **CONFLICT with fish farming** - damage in farms, local game. Fluctuating population: growth 1984-2006, decline 2007-2015, stabilization 2016-2018.

Physical Characteristics

Glossy black plumage with a bronzy-brown sheen on the back and wings. In breeding plumage: white flank patches, white head and neck markings, and a pale crest. Juveniles have white underparts (penguin-like when standing upright). In winter: only a white chin patch, otherwise uniformly black. Long, slender neck; relatively small head; long, strongly hooked bill. Green eyes are diagnostic. Short, webbed legs with all 4 toes joined by webbing. Minor sexual dimorphism — males are slightly larger than females.

Habitat & Distribution

Global distribution across 5 continents (except Antarctica and South America). Resident in the south, migratory in the north. In Romania: the Danube Delta holds 90% of the national population, with additional birds on major rivers, and wetlands of east and south-east Romania. Prefers large, deep, fish-rich waters; marine coasts; large lakes; rivers and canals. Cannot tolerate frozen waters in winter. Requires trees or solid structures for nesting and for the characteristic wing-drying posture.

Behaviour & Feeding

An exceptional diver: dives to 45 m depth, remaining submerged for up to 70 seconds per dive. Diet is almost exclusively fish: 0.9–1.4 kg per bird per day. Hunts in coordinated groups of up to 500 individuals, often alongside pelicans, which benefit from the same disturbed fish shoals. Cannot swallow fish longer than 20 cm. After fishing, dries wings in the characteristic upright posture — cormorant feathers are not fully waterproof, which actually facilitates diving by reducing buoyancy. Known to professional fishermen as a “natural barometer of the Danube” — experienced delta fishermen follow cormorant flocks to locate concentrations of fish.

Life Cycle & Reproduction

Sexual maturity at 2–3 years. Strictly colonial nesting, with the breeding season running from April to July. Mixed colonies are the rule in the Danube Delta: cormorants nest alongside Little Cormorants, egrets, herons, Spoonbills, and Glossy Ibis — frequently sharing the same trees. Nests are large platforms of branches lined with fine vegetation. Up to 50 nests may occupy a single large tree. Clutch: 2–6 pale blue eggs (usually 3–4), incubated for 27–31 days by both parents alternately. Chicks fledge at approximately 50 days.

Conservation Status

Least Concern (LC) globally. Population in the Danube Delta has fluctuated considerably: peak of 17,500 pairs (2007), a low of 5,060 pairs (2015), and partial stabilisation at 7,524–8,157 pairs (2016–2018). The species is at the centre of a long-running conflict with fish farming interests, leading to illegal persecution. Principal threats include illegal shooting at fish farms and fish ponds, tourist disturbance at breeding colonies, declining wild fish stocks, and freezing conditions in severe winters. The mixed nature of nesting colonies — cormorants nesting alongside conservation-priority species such as egrets and Spoonbills — makes any population management intervention extremely delicate.

Sources

  • Pasaridinromania.sor.ro
  • INCDDD — Cormorant monitoring reports
  • Newsweek România
  • Wikipedia: Great cormorant