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Biology ( englanti )

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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).
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Conservation ( englanti )

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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).
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Description ( englanti )

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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).
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Habitat ( englanti )

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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)
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Range ( englanti )

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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).
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Status ( englanti )

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

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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).
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Cape cormorant ( englanti )

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The Cape cormorant or Cape shag (Phalacrocorax capensis) is a bird endemic to the southwestern coasts of Africa.

It breeds from Namibia south to southern Western Cape. In the nonbreeding season, it may be found as far north as the mouth of the Congo, and also extends up the east coast of South Africa as far as Mozambique. In the 1970s, the breeding population was estimated as over 1 million in Namibia alone. However, the IUCN now classifies it as "Endangered" due to a very rapid decline in the population over the last three generations.[1]

The Cape cormorant is an almost entirely glossy black bird, though in breeding condition it has a purplish tinge and a few white plumes on head, neck, and cloacal areas. Its gular skin is a deep orangey yellow; unusually for a cormorant, its lores are feathered. The bird's wing is about 240–280 mm in extent, and it weighs 800–1600 grams, with little sexual dimorphism.

Cape shags commonly forage in flocks, taking schooling fish from mid-water, such as pilchards, anchovies, and sand eels. Its prey are typically much smaller than those of the sympatric bank cormorant. Their major predators are black-backed jackals, which take the occasional adult while it is roosting, and nest-site predators such as great cormorants, eastern great white pelicans, and kelp gulls.

Like a number of other related cormorant species, the Cape cormorant is placed by some authorities (e.g. Johnsgaard) in the genus Leucocarbo.

Gallery

References

  1. ^ a b BirdLife International (2018). "Phalacrocorax capensis". IUCN Red List of Threatened Species. 2018: e.T22696806A132594943. doi:10.2305/IUCN.UK.2018-2.RLTS.T22696806A132594943.en. Retrieved 11 November 2021.
  2. ^ BirdLife International (2013). "Phalacrocorax capensis". IUCN Red List of Threatened Species. 2013. Retrieved 26 November 2013.old-form url
  • Johnsgaard, P.A. (1993). Cormorants, darters, and pelicans of the world. Washington DC: Smithsonian Institution Press. ISBN 1-56098-216-0

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Cape cormorant: Brief Summary ( englanti )

tarjonnut wikipedia EN

The Cape cormorant or Cape shag (Phalacrocorax capensis) is a bird endemic to the southwestern coasts of Africa.

It breeds from Namibia south to southern Western Cape. In the nonbreeding season, it may be found as far north as the mouth of the Congo, and also extends up the east coast of South Africa as far as Mozambique. In the 1970s, the breeding population was estimated as over 1 million in Namibia alone. However, the IUCN now classifies it as "Endangered" due to a very rapid decline in the population over the last three generations.

The Cape cormorant is an almost entirely glossy black bird, though in breeding condition it has a purplish tinge and a few white plumes on head, neck, and cloacal areas. Its gular skin is a deep orangey yellow; unusually for a cormorant, its lores are feathered. The bird's wing is about 240–280 mm in extent, and it weighs 800–1600 grams, with little sexual dimorphism.

Cape shags commonly forage in flocks, taking schooling fish from mid-water, such as pilchards, anchovies, and sand eels. Its prey are typically much smaller than those of the sympatric bank cormorant. Their major predators are black-backed jackals, which take the occasional adult while it is roosting, and nest-site predators such as great cormorants, eastern great white pelicans, and kelp gulls.

Like a number of other related cormorant species, the Cape cormorant is placed by some authorities (e.g. Johnsgaard) in the genus Leucocarbo.

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Description ( englanti )

tarjonnut World Register of Marine Species
Length: 61-64 cm. Plumage: Black. Bare parts: iris turquoise; face and gular skin yellow to yellow-orange; bill legs and feet black; eyelids with bright blue beads. Habitat: coastal waters, estuaries.

Viite

Brown, L.H., E.K. Urban & K. Newman. (1982). The Birds of Africa, Volume I. Academic Press, London.

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World Register of Marine Species