Spheniscus demersus

African Penguin

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Description

The African penguin is a medium-sized penguin, and the only species breeding on the African continent (5). Penguins have a robust, heavyset body and this species are black on the back and white below, with variable black markings on the breast and belly (2). Juvenile plumage is slate blue on the upper surface and this gradually turns darker, developing the adult black-and-white facial pattern in the second or third year. Penguins have small muscles at the base of each feather that enable them to be held tightly against the body whilst in water, forming a waterproof layer; alternatively, on land they are held erect, trapping an insulating layer of air around the body (5). These penguins are also known as 'jackass penguins' due to their loud, braying call (6).

Geography

Spheniscus demersus, commonly known as African, black-footed, or jackass penguin, is the only penguin species found on the African continent. This species inhabits the Benguela and western Agulhas ecosystems of southern Africa. African penguins form colonies near a chain of islands between Hollamsbird Island, Namibia, and Bird Island in Algoa Bay, South Africa.

Biogeographic Regions: ethiopian (Native )

Ecosystem

African penguins live in large colonies on rocky coastlines of southwest Africa. They can swim up to 20 kph and can travel 30 to 70 km during each trip. They spend the night gathered together on shore and much of the day feeding in the water.

Range depth: 130 (high) m.

Average depth: 30-60 m.

Habitat Regions: temperate ; terrestrial

Aquatic Biomes: coastal

Conservation

African penguins are classified as vulnerable. Since the early 1900s, the African penguin population has been in decline. The initial decline was due to commercial sales of eggs and disturbance of nesting birds. Presently, the species is threatened by oil pollution.

 

Threats

Population declines are largely attributed to food shortages, resulting from large catches of fish by commercial purse-seine fisheries, and environmental fluctuations. A decrease in foraging effort at the St Croix Island colony following the establishment of a 20 km no-take zone provides some support for this theory26. An eastward shift in sardine and anchovy populations is also blamed, with the biomass of these species near the largest breeding islands west of Cape Town falling sharply since 200212. The abundance of these prey species is known to influence breeding success, which may often be too low to maintain population equilibrium14. Human disturbance and egg-collecting appear to have been additional factors in the species's declines2. Tourists may cause nest-burrows to collapse, and their presence in large numbers may deter young birds from breeding. Mortality from oil spills is serious and may increase if proposed development of harbours close to colonies proceeds. In addition, most of the population is confined to just two areas, both near to major shipping ports5. There has been a dramatic increase in the number of birds oiled since 1990: two individual oil spills (in 1994 and 2000) have killed 30,000 individuals, despite successful rehabilitation programmes5. In addition, breeding success on Robben island fell to 0.23 chicks per pair in 2000, compared with an average of 0.62 ±0.19 over the other 15 years from 1989 to 200414. Without continuing rehabilitation, the population is set to decrease 17-51% over the next 20 years5. However, rehabilitation does not necessarily prevent problems in the years after a spill. During 2001-2005, pairs involving at least one bird rehabilitated from the oil spill in 2000 achieved lower fledging success (43%), mostly owing to higher mortality in older chicks, compared to unaffected pairs (61%) and those involving at least one bird affected by a previous oil spill (71%)9. This may indicate physiological or behavioural problems that reduce the parents' ability to meet the food requirements of older chicks, perhaps owing to the toxicity of the heavy oil in the 2000 spill, or the effects of prolonged captivity and time between oiling and washing9. Guano collection has historically been a major cause of disturbance at many colonies and its removal has deprived penguins of nest-burrowing sites, causing birds to nest on open ground where they are more vulnerable to heat stress resulting in the abandonment of nests, flooding of nests by rain and increased predation22. The cape fur seal Arctocephalus pusillus competes with penguins for food, displaces them from breeding sites and is a periodic predator. Limited mortality in fishing nets may increase if gill-nets are set near colonies2. Recently the potentially major effects of individual storms on breeding colonies at certain sites has been highlighted4. Sharks take birds at sea and Kelp Gulls Larus dominicanus and feral cats prey on eggs and chicks at colonies1.

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