The African penguin (Spheniscus demersus) is a medium-sized penguin, and the only penguin species breeding on the African continent. Like all penguins, the African penguin has a robust, heavyset body, and this species is black on the back and white below, with variable black markings on the breast and belly. Juvenile African penguins are slate blue on the upper surface, gradually turning darker and 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 the feathers to be held tightly against the body whilst in water, forming a waterproof layer; alternatively, on land the feathers are held erect, trapping an insulating layer of air around the body. The African penguin is also known as the ‘jackass penguin’ due to its loud, braying call.
Biology
African penguins are colonial breeders, with pairs returning to the same site year after year. Unusually, there is no fixed breeding season, although nesting peaks in Namibia between November and December and in South Africa between March and May. Nests are situated in burrows or depressions under boulders and bushes, where they will receive some protection from the potentially harsh temperatures. The clutch size of the African penguin is usually two, and both adults take it in turns to incubate the eggs for a period of about 40 days; penguins have a bare patch of skin on the lower abdomen (known as the ‘brood patch’) which allows greater transfer of heat to the eggs. Following hatching, the adults will continue to guard the chicks until they are about 30 days old, regurgitating food straight from their stomach following foraging trips. Chicks are then left alone in crèches whilst the adults forage; at between 60 and 130 days old they develop juvenile plumage and leave the colony.
The African penguin feeds on fish such as anchovies (Engraulis capensis) and sardines (Sardinops sagax). Adapted for its aquatic lifestyle, the African penguin can reach speeds of 20 kilometres per hour in the water and travel from 30 to 70 kilometres in a single trip; average dives last for 2.5 minutes, reaching depths of 60 metres. Penguins have waterproof coats that need to be constantly maintained by preening, when a waxy substance is distributed from the base of the tail. Even with these measures, the plumage is replaced yearly, and African penguins come ashore to moult over 20 days between November and January in South Africa and between April and May in Namibia.
Behavior
Diet
African penguins forage in the open sea, where they pursue pelagic fish such as pilchards and anchovies (e.g. Engraulis capensis), and marine invertebrates such as squid and small crustaceans. Penguins normally swim within 20 km of the shore. A penguin may consume up to 540 grams of prey every day, but this may increase to over 1 kg when raising older chicks.
Due to the collapse of a commercial pilchard fishery in 1960, African penguin diet has shifted towards anchovies to some extent, although available pilchard biomass is still a notable determinant of penguin population development and breeding success. While a diet of anchovy appears to be generally sufficient, it is not ideal due to lower concentrations of fat and protein. Penguin diet changes throughout the year; as in many seabirds, it is believed that the interaction of diet choice and breeding success helps the penguins maintain their population size. Although parent penguins are protective of their hatchlings, they will not incur nutritional deficits themselves if prey is scarce and hunting requires greater time or energy commitment. This may lead to higher rates of brood loss under poor food conditions.
Breeding
The African penguin is monogamous. It breeds in colonies, and pairs return to the same site each year. The African penguin has an extended breeding season, with nesting usually peaking from March to May in South Africa, and November and December in Namibia. A clutch of two eggs are laid either in burrows dug in guano, or scrapes in the sand under boulders or bushes. Incubation is undertaken equally by both parents for about 40 days. At least one parent guards the chicks until about 30 days, whereafter the chick joins a crèche with other chicks, and both parents head out to sea to forage each day.
Chicks fledge at 60 to 130 days, the timing depending on environmental factors such as quality and availability of food. The fledged chick then go to sea on their own and return to their natal colony after a lengthy time period of 12–22 months to molt into adult plumage. When penguins molt, they are unable to forage as their new feathers are not waterproof yet; therefore they fast over the entire molting period, which in African penguins takes about 20 days.
African penguin females remain fertile for 10 years. African penguins spend most of their lives at sea until it comes time for them to lay their eggs. Due to the high predation by larger mammals on the mainland, the penguins will go offshore to an island for protection from mammals and natural challenges. African penguins usually breed during the African winter when temperatures are lower. Ideally, eggs are incubated in a burrow dug into the guano layer, which provides a suitable temperature regulation, but the widespread human removal of guano deposits has rendered this type of nest unfeasible at most colonies. To compensate, penguins dig holes in the sand, breed in the open, or make use of nest boxes if such are provided. The penguins spend three weeks on land to provide for their offspring, after which chicks may be left alone during the day while the parents forage. The eggs are three to four times bigger than hen’s eggs. Parents usually feed hatchlings during dusk or dawn.
In 2015, when foraging conditions were favorable, more male than female African penguin chicks were produced in the colony on Bird Island. Male chicks also had higher growth rates and fledging mass, and therefore may have higher post-fledging survival than females. This coupled with higher adult female mortality in this species may result in a male biased adult sex ratio, indicating that conservation strategies focused on benefiting female African Penguins may be necessary.
Predation
The average lifespan of an African penguin is 10 to 27 years in the wild, and can live up to 30 in captivity. However, the African penguin may often fall to predators. Predators in the ocean include sharks, Cape fur seals and, on occasion, orcas. Land-based enemies include mongooses, genets, caracals, leopards, domestic cats, and the kelp gull which steals their eggs and newborn chicks. Pressure from terrestrial predators is higher if penguins are forced to breed in the open in the absence of suitable burrows or nest boxes.
Range and Habitat
Found in southern Africa, the African penguin is known to breed on 24 islands between Hollamsbird Island, Namibia and Bird Island in Algoa Bay, South Africa. African penguins are generally found within 40 kilometres of the coast, emerging onto rocky offshore islands to breed, rest and molt.
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