Cape cormorant (Phalacrocorax capensis)

Description

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Cape cormorant fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Cape cormorant description

The most distinctive feature of this southern African seabird is the bright orange-yellow patch of bare skin at the base of its bill, which sits in stark contrast against its glossy black plumage, tinged with a bluish-purple sheen ^{(2) (3)}. The black bill, with a blue-grey base ⁽³⁾, has completely sealed nostrils ⁽⁴⁾, which means the Cape cormorant must breathe through its mouth, but is able to dive unhindered into the water in pursuit of prey. Like other Pelecaniformes (a group of large seabirds), the Cape cormorant has webbing between all four toes, making it a strong swimmer and proficient predator of fish ⁽⁴⁾. Its affinity for the sea is reflected in the common name, cormorant, which is a corruption of the French words corbeau marin, meaning sea crow ⁽⁵⁾. Juvenile Cape cormorants differ from adults in their dark brown plumage and pale underparts, but all ages have bright turquoise eyes ^{(2) (3)}. Although said to be a fairly silent bird ⁽²⁾, the Cape cormorant does have a variety of vocalisations, including a repeated, low-pitched cluck made by the male during courtship and a hiss that escalates into a bark when threatened ⁽³⁾.

Also known as

Cape shag.

French

Cormoran du Cap.

Size

Length: 61 – 65 cm ⁽²⁾

Cape cormorant biology

This sleek seabird forages typically less than ten kilometres from shore, in the cool waters of the north-flowing Benguela Current ⁽⁶⁾. It feeds in vast flocks of thousands of individuals on shoals of fish, often in association with terns, penguins and gannets. With a little leap clear of the water’s surface, the Cape cormorant dives into the ocean ⁽³⁾, the surface feathers of its glossy plumage becoming easily soaked, reducing buoyancy and allowing the cormorant to descend more easily into the water. The inner feathers, however, remain waterproof and provide insulation in the chilly water ⁽⁴⁾. Each dive lasts for around 30 seconds, and each day there are two feeding bouts of around 30 minutes each ⁽³⁾. The Cape cormorant feeds principally on pilchard, as well as anchovies, sandeels, sardines, hake and, in smaller amounts, crabs, lobsters, mussels and squid ⁽³⁾.

Breeding colonies of Cape cormorants are equally immense as the feeding flocks. Breeding may take place at any time of the year, but egg-laying primarily takes place between September and February. The male gathers dried seaweed, sticks, and floating ocean debris, such as plastic, netting and rope, from which the female constructs a nest, measuring about 30 centimetres across. Into this flimsy structure is laid a clutch of one to five eggs (most commonly two to three), which are laid at intervals of two to three days. Both the male and female share the task of incubating the eggs for 22 to 28 days, and when the young hatch, both bring food to the young ⁽³⁾. Parental care even extends to sheltering the newly hatched young from the sun, with adults observed standing with their wings outstretched with their backs to the sun ⁽³⁾. After five to six weeks, the young leave the nest to form small crèches of up to ten birds, and by nine weeks the young can fly ⁽³⁾. This fledgling population is very vulnerable to predators; Cape fur seals prey heavily on seabirds in southern Africa, and Cape cormorants are particularly susceptible to predation when they land on the waters surrounding breeding islands ⁽⁷⁾. Cape cormorants are known to live for up to nine years ⁽³⁾.

Cape cormorant range

Found only in southern Africa, the Cape cormorant breeds along the coast of Namibia and the west coast of South Africa. Outside of the breeding season, Cape cormorants can be found as far north as the Congo River, and round to Durban on the east coast of South Africa ^{(3) (6)}.

See this species on Google Earth.

Cape cormorant habitat

The Cape cormorant is a marine bird, which breeds in enormous colonies in relatively remote and inaccessible habitats, including the flat areas of small offshore islands, coastal cliffs, artificial guano platforms and occasionally on other artificial structures ^{(3) (6)}. Sometimes it enters harbours and estuaries ⁽²⁾

Cape cormorant status

Classified as Near Threatened (NT) on the IUCN Red List ⁽¹⁾.

Cape cormorant threats

Cape cormorant populations have been affected by a number of factors over the years ⁽⁸⁾. The mining of guano caused considerable disturbance of breeding colonies in the past, resulting in declines, whereas more recently, overfishing of one of the cormorant’s preferred prey species, the South African pilchard (Sardinops ocellata), impacted numbers of this species ⁽⁶⁾. Outbreaks of disease in Cape cormorant populations has also had devastating affects, with more than 14,500 cormorants dying in 1991 from avian cholera on eight islands off western South Africa ⁽⁹⁾, and a further 8,000 individuals perishing on Dyer Island from an outbreak of the same disease in 2004 ⁽⁶⁾. In addition, oil spills within the range of the Cape cormorant is a continual potential threat ⁽⁶⁾.

Although many fluctuations seen in Cape cormorant populations are due to natural cycles in the availability of prey, some recent declines of certain prey species, such as the Cape anchovy (Engraulis capensis), are of concern ^{(6) (8)}. Given the close relationship between Cape cormorant populations and the availability of their prey, global climate change, which could affect ocean conditions and therefore prey distribution and availability, may have serious consequences for this seabird ⁽⁶⁾.

Cape cormorant conservation

Although not yet considered to be at risk of extinction ⁽¹⁾, the Cape cormorant is listed on Annex II of the African-Eurasian Waterbird Agreement, which requires countries party to the agreement to engage in a wide range of conservation actions. While South Africa has signed to the agreement, Namibia currently has not ⁽¹⁰⁾. As a result of guano mining causing declines in the Cape cormorant in the past, guano platforms were constructed to increase the area of suitable breeding ground available ⁽⁶⁾. In addition, measures were implemented on Dyer Island in 2004 to control the outbreak of avian cholera. This involves the prompt removal of carcasses of birds which have been believed to been killed by avian cholera, which hinders the spread of this highly contagious disease ^{(6) (11)}. Further measures, including monitoring trends in stocks of prey species and enforcing measures to prevent oil spills, have been recommended to ensure that this distinctive marine bird does not become threatened ⁽⁶⁾.

View information on this species at the UNEP World Conservation Monitoring Centre.

Find out more

For further information on conservation of the Cape cormorant see:

• BirdLife International:
  www.birdlife.org/datazone/sites/index.html?action=SpcHTMDetails.asp&sid=3682&m=0
• CapeNature:
  http://www.capenature.co.za/resources.htm?sm[p1][category]=333&sm[p1][persistent]=1&

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References

1. IUCN Red List (April, 2008)
   http://www.iucnredlist.org
2. Sinclair, I., Hockey, P., Hayman, P. and Arlott, N. (2005) The Larger Illustrated Guide to Birds of Southern Africa. Struik Publishers, Cape Town.
3. Nelson, J.B. (2005) Pelicans, Cormorants and Their Relatives. Oxford University Press, Oxford.
4. Burnie, D. (2001) Animal. Dorling Kindersley, London.
5. Ruschenberger, W.S.W., Milne-Edwards, H., Comté, A. and Comte, A.J. (1845) Elements of Ornithology: Prepared for the Use of Schools and Colleges. University of Wisconsin, Madison.
6. BirdLife International (September, 2008)
   http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=3682&m=0
7. Johnson, R.L., Venter, A., Bester, M.N. and Oosthuizen, W.H. (2006) Seabird predation by white shark (Carcharodon carcharias) and Cape fur seal (Arctocephalus pusilluspusillus) at Dyer Island. South African Journal of Wildlife Research, 36(1): 23 - 32.
8. Crawford, R.J.M., Dyer, B.M., Kemper, J., Simmons, R.E., Upfold, L. and vaz Velho, F. (2007) Trends in numbers of Cape Cormorants (Phalacrocorax capensis) over a 50-year period, 1956/57–2006/07. In: Kirkman, S.P. (Ed) Final Report of BCLME (Benguela Current Large Marine Ecosystem) Project on Top Predators as Biological Indicators of Ecosystem Change in the BCLME. Avian Demography Unit, Cape Town.
9. Crawford, R.J.M., Allwright, D.M. and Heyel, C.W. (1992) High mortality of cape cormorants (Phalacrocorax capensis ) off western South Africa in 1991 caused by Pasteurella multocida. Colonial Waterbirds, 15(2): 236 - 238.
10. AEWA (September, 2008)
    http://www.unep-aewa.org
11. Waller, L.J. and Underhill, L.G. (2007) Management of avian cholera Pasteurella multocida outbreaks on Dyer Island, South Africa, 2002–2005. African Journal of Marine Science, 29(1): 105 - 111.