African Penguin (Spheniscus demersus)

The African Penguin, also known as the Jackass Penguin for its donkey-like braying, was ruthlessly exploited by humans in the 20th century leading to a 90% decrease in their population. Guano scraping occurred for nearly 150 years when 200,000 tonnes of guano were removed from the islands around South Africa. Penguins need this precious material to make their burrows, which provide them with shelter from the elements and predators such as gulls and skuas. Eggs were also collected by humans, as they were considered a delicacy, with about 13 million collected from Dassen Island alone. Currently, penguins are still threatened by competition with commercial fisheries for pelagic fish prey. We believe this has caused 60% of St. Croix’s penguin population to disappear within 6 years. Another current threat is that of oil pollution. A penguin with even a splash of oil on its feathers will lose its insulation from the heat sapping sea water and will eventually die of hypothermia. Click here to read about current penguin research, with the aim of conserving and improving the current penguin population.

The African penguin stands at about half a metre tall and weighs between 2 and 3.5kg. They have black spots on their chests which are unique to each individual, almost like a fingerprint. Although clumsy and comical on land they are sleek and agile in the water, spending the majority of their lives at sea. Where all other birds have pneumatised bones, which are filled with air pockets to keep them light, penguins have heavy solid bones allowing them to dive more efficiently. Another adaptation to life at sea is the evolution of a preen gland. This gland produces oil which penguins transfer to their feathers, using their bill, to keep the feathers waterproof. These penguins can dive to depths of up to 130 metres though they usually only dive for 3-5 minutes reaching 30 metres.

As cooperative feeders, these birds will go out to sea in large groups, travelling up to 110km in search of food. They feed on sardines, anchovies and squid. Once the prey is located they will surround it and drive it up to the surface, attacking from below. Adult penguins need about 300g of fish per day but have to find another 500g when they have chicks to feed. Penguins don’t have easy access to fresh water but get some from their prey and also take in salt water. This gets desalinated by their salt glands and the excess, concentrated salt is expelled through their nostrils.

The peak breeding season for African penguins is from March until May, during which time adults will lay two eggs which are incubated for 40 days, with both parents alternating 2 and a half day shifts. Once hatched, new-born chicks are closely guarded for the first 30 days after which they are often observed in groups called a crèche. Chicks will fledge between 2 and 4 months at which point they will go out to sea and not return for a year or two. During this time they will moult and take on their adult plumage. The moulting process takes about 19-20 days during which they must remain on land. For five weeks prior to moulting penguins will remain at sea, eating almost 1.2kg of fish per day to build up their fat reserves. Penguins increase the weight of their bodies by about 30% in order to survive this moulting, as they lose about half of their body weight during the process.