African Penguin (Spheniscus demersus)
African Penguin Characteristics
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African penguins look much like the Humboldt penguins. African penguins have a broad band of black that is in the shape of an upside-down horseshoe on their fronts. They have black spots scattered over their chest area.
African penguins make a loud braying sound that has given them the name the 'Jackass penguin'. African penguins stand about 27 inches (60 cm tall) and weigh from 7 to 11 lbs. (2.5 to 4 kg).
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African penguins live and breed on the coast of South Africa and on the off shore islands. During the 17th and 18th century the African penguin was killed for food and oil. More recently the collection of guano has destroyed nesting areas. At one time the population was estimated to be in the millions. This number has decreased to about 160,000 in 1993.
African Penguin Range
The African Penguin is the only penguin species that breeds in Africa and it is found nowhere else. Its distribution coincides roughly with the cold, nutrient rich, Benguela Current. The distribution of African Penguins is further determined by the availability of offshore islands as breeding sites.
The African penguin's breeding range extends from Hollamsbird Island, off central Namibia, to Bird Island in Algoa Bay. Non-breeding birds disperse from southern Angola to Kwazulu-Natal, with vagrants from Gabon and central Mozambique. There are 27 extant breeding colonies, eight islands and one mainland site along the coast of southern Namibia, 10 islands and two mainland sites along the coast of the Western Cape Province (South Africa), and six islands in Algoa Bay (Eastern Cape Province, South Africa).
Breeding no longer occurs at 10 localities where it formerly occurred or has been suspected to occur. The present population of the African penguin is probably less than 10% of that in 1900, when there was estimated to be about 1.5 million birds on Dassen Island alone. By 1956 the population had fallen to roughly half that in 1900, and had halved again by the late 1970s, when there was an estimated 220,000 adult birds. By the late 1980s the number had dropped to about 194,000 and in the early 1990s there was an estimated 179,000 adult African penguins.
African Penguin Diet
African Penguins feed primarily on shoaling pelagic fish such as anchovies, pilchards (sardines), horse mackerel and round herrings, supplemented by squid and crustaceans. There are regional differences in diet, and in some regions major changes in diet have followed human exploitation of their prey. When on the hunt for prey, African Penguins can reach a top speed of close to 20 km/h.
The distance that African penguins have to travel to find food varies, both temporally and spatially. On the west coast a typical foraging trip could range from 30 to 70 km. for a single trip. On the south coast, foraging birds cover an average of 110 km. per trip. When penguins are feeding their young, the distance they can travel from the breeding colony is more limited. An average dive of an African Penguin lasts about two and a half minutes and is regularly about 30 metres in depth, although dive depths of up to 130 metres have been recorded.
African Penguin Nesting
The nests are built far apart from other nests. They can be built under bushes or on sandy beaches. Two eggs are usually laid and in years when there is plenty of food both chicks will survive. Incubation takes 38 to 41 days for the the eggs to hatch. This task is shared equally by both parents taking a 1 to 3 day shift. The chicks are kept warm and protected for about 40 days after hatching by both parents. The chicks get their adult feathers when they are 70 to 100 days old. At this time they go to sea and are on their own.
African Penguin Breeding
African Penguins start breeding from between two to six years of age, but normally at four years. As with most other penguins, the African Penguin breeds colonially, mostly on rocky offshore islands, either nesting in burrows they excavate themselves, or in depressions under boulders or bushes. Historically, nests were excavated in the cap of guano that existed on most islands. However, with the removal of the guano for commercial purposes, surface nesting and nesting under bushes and other objects has become more frequent. Shelter at the nest site is important to provide shade (and protection against the temperate climate) and for protection against predators of eggs and chicks, such as Kelp Gulls and Sacred Ibises.
Unlike many other bird species, African Penguins have an extended breeding season. In most colonies, birds at some stage of breeding will be present throughout the year. Broad regional differences do exist, though, and the peak of the breeding season in Namibia (November and December) tends to be earlier than the peak for South Africa (March to May).
African Penguins are monogamous and the same pair will generally return to the same colony and often the same nest site each year. About 80 to 90% of pairs remain together in consecutive breeding seasons, and some are known to have remained together for over 10 years. The modal clutch size for African Penguins is two, and the incubation period about 40 days, with the male and female participating equally in the incubation duties. The length of the incubation shift is dependant on the availability of food at the time, but is typically about two and a half days.
Both parents continue to brood the chicks and for about the first 15 days the chicks are constantly brooded by one of the adults. After this, the chicks attain full control over their body temperature. However, at this stage the chicks are still at risk from predators, and the adults continue to guard the chicks until they are about 30 days old, after which both parents can go to sea simultaneously. Chicks that are left alone often form creches, which serve more to reduce attacks on chicks from adults than to avoid predation.
African Penguin chicks can fledge anytime from 60 to 130 days of age. The fledging period and the fledging weight of chicks, as well as the number of chicks in the brood that are successfully fledged, are dependent on the availability and quality of food. The adults continue to feed chicks while the young are still present at the colony. When the young eventually leave the colony, they do so without their parents. These juveniles remain away from their natal colonies for anything from 12 to 22 months, after which time they return, normally to their natal colony, to molt into adult plumage.
Little is known about the juvenile dispersal period for African Penguins, except that juveniles from the south-western Cape tend to disperse northwards up towards Namibia and birds from the Eastern Cape tend to disperse southwards. The molt cycle of African Penguins is generally more synchronous than the breeding cycle. In South Africa most penguins molt from November to January, while in Namibia most molt in April and May.
African Penguin Adaptions
Penguins are adapted primarily to cool aquatic environments, and the need to reduce heat loss is of major importance to all penguins. However some species, including the African Penguin, have been able to successfully exploit warm terrestrial environments. Behavioural and physiological adaptations have enabled the African Penguin to overcome the problem of being over-insulated for life on land in a temperate climate.
One of the ways in which African Penguins have adapted to terrestrial life in the temperate zone is to confine their activities at breeding sites largely to dawn and dusk periods. Breeding birds nest mostly in burrows or under some other form of shelter, such as boulders and bushes, which provide some protection from the intense solar radiation during the day. Birds that are not incubating or brooding chicks, and other non-breeding birds, spend the day at sea or loaf in beach groups and swim regularly. Some birds do remain in the open (i.e. outside of burrows and other sheltered nests) in the colony; but these birds generally orientate themselves with their backs to the sun so that their feet, flippers and oral surfaces are shaded, thereby facilitating radiation and convective heat loss. Physiological responses to heat stress include panting (evaporative cooling) and moderate hypothermia.
African Penguin Conservation
Given an annual rate of decline of about 2% per year, there is considerable concern about the long-term viability of African Penguins in the wild. By the late 1990s the population had recovered slightly, and in 1999 there was an estimated 224,000 individuals. The African Penguin is classified as Vulnerable in the South African Red Data Book for birds, is considered Vulnerable in terms of the IUCN threatened species categories, and is listed in Appendix II of CITES and the Bonn Convention for the conservation of migratory species.
The reasons for the significant decline in the African Penguin populations are well known. Initially, the decline was due mostly to the exploitation of penguin eggs for food and habitat alteration and disturbance associated with guano collection at breeding colonies. These factors have now largely ceased and the major current threats include competition with commercial fisheries for pelagic fish prey and oil pollution. Other threats include competition with Cape Fur Seals for space at breeding colonies and for food resources, as well as predation by seals on penguins. Feral cats are present and pose a problem at a few of the colonies. African Penguins also face predation of eggs and chicks by avian predators such as Kelp Gulls and Sacred Ibises, while natural terrestrial predators, such as mongoose, genets and leopard are present at the mainland colonies.
The African penguin is a protected species, but their habitats continue to be damaged by oil spills from tankers off the Southern coast of Africa. Recently a successful effort has been made to establish new breeding colonies of the African penguins in the area. There are also rescue services to aid penguins that have been harmed by the oil slicks.
