Cormorant (Phalacrocorax carbo)
|Also known as:||great cormorant, white-breasted cormorant|
|Size||Wingspan: 121-149 cm (1)|
Length: 77-94 cm (1)
The cormorant is classified as Least Concern (LC) on the IUCN Red List (1). It receives general protection under the Wildlife and Countryside Act 1981, and listed under Appendix III of the Bern Convention. Classified as a species of conservation concern by the UK Biodiversity Action Plan, although not a priority species (2). Included in the Birds of Conservation Concern Amber List (medium conservation concern) (8).
The cormorant (Phalacrocorax carbo), a large water bird, has a long neck, giving it something of a primitive, reptilian appearance (3). Adults are black with a bluish or green sheen. At the base of the bill is an area of bare, yellow skin surrounded by white (1). During the breeding season there is a white patch on the thigh, and throughout the year a variable amount of white occurs on the crown and back of the neck (1). Juveniles are dark brown and have a white area on the underparts (1). A variety of deep vocalisations are produced in colonies (1). The name cormorant is derived from the Latin 'corvus marinus', which means 'sea crow' (4).
The cormorant occurs around the coastline of Great Britain, but is absent from much of north east Scotland (3). Although typically thought of as a sea bird, inland breeding colonies do occur, these are now increasing after being largely wiped out due to persecution since medieval times (5). Globally this is a very widespread species, occurring in most temperate areas of the Old World (6).
Coastal populations occur in shallow inshore marine waters (6) where there are rocky islands or cliffs (3). Inland cormorant colonies nest in trees close to freshwater lakes, reservoirs and gravel pits (3), and these are increasing (5).
Coastal cormorants make their nest on rocky ledges or islands out of seaweeds; inland tree-nesting birds construct their nest from twigs. The faeces are so acidic that nest-trees usually die within about three years (3). Either three or four pale blue, chalky eggs are laid, these are incubated for 28 to 31 days during which time they are placed on the adult's feet and warmed by the body (3). In the first few days of life the chicks feed on liquid regurgitated by the parents, they then take solid food from the parent's throats (3). After 50 days of life the young fledge, and return to the colony to breed at two to three years of age (3). During the winter, they roost together each evening, sometimes in their hundreds (9).
Cormorants feed exclusively on fish (6), which are caught by means of dives from the surface of the water (6). A wide range of fish is taken, and this bird's efficiency as a predator has brought it into conflict with anglers (3).
The cormorant has special feathers, which allow the water to penetrate, enabling the bird to swim well under water. After fishing, cormorants stand in a characteristic pose, with wings out and neck extended (3). This was thought to be to dry their wings, but is now considered to help digestion (9).
People involved in angling and fisheries are concerned that the increase in numbers of cormorants in the UK is having a negative impact on fish stocks (5), and some are calling for the legal protection of the species to be reduced (3). Conservationists believe that any conflicts can be resolved on each site and are worried that such a move would affect the conservation status of the species (5).
Like all birds, the cormorant receives protection under the Wildlife and Countryside Act of 1981; it is illegal to kill wild birds and their nests and eggs cannot be taken or destroyed (5).
For more information on the cormorant and other bird species:
Information authenticated by the RSPB:
- Incubate: to keep eggs warm so that development is possible.
IUCN Red List (February, 2011)
- Mullarney, K., Svensson, L., Zetterstrom, D., & Grant, P.J. (1999) Collins Bird Guide. HarperCollins Publishers Ltd, London.
UK Biodiversity Action Plan (1995). See:
RSPB (2003) The population status of birds in the UK
RSPB cormorant information (July 2002).
- Greenoak, F. (1979) All the birds of the air; the names, lore and literature of British birds. Book Club Associates, London.
The Moran Committee. Cormorants: The facts (July 2002):
- Lack, P. (1986) The Atlas of Wintering Birds in Britain and Ireland. T. & A. D. Poyser Ltd, Calton.
- RSPB (2003) Pers. comm.