A Penguin of the Tropics?

Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"

Penguins are associated with Antarctica and the islands of the freezing southern oceans, but a few species prefer somewhat warmer climes. This is one. The African Penguin, Spheniscus demersus, is the only penguin that regularly occurs on the continent of Africa. It can be found along the western, southern and a bit of the eastern coast of South Africa, and most of the coast of Namibia.

So is this a tropical penguin then? While in Namibia its distribution crosses the Tropic of Capricorn, actually like other penguins it does best in cold waters. What happens here is that ocean currents transport cold water from the Antarctic regions northwards along the western coast of Africa. This is called the Benguela Current. Cold ocean water tends to be very rich in fish because it is richer in oxygen; the strong current also causes an upwelling of nutrients which can support a large and complex food web, including the fish, squid and crustaceans the penguins feed on. The penguins are much rarer in the eastern subtropical waters of South Africa.

Voice of a Donkey

This penguin in South Africa is also known as a Jackass Penguin. This rather unflattering name has nothing to do with its brainpower or personality, it is only on account of its voice! African Penguins are noisy and have a loud braying or trumpeting call that can sometimes sound quite like a braying donkey.

The Banded Penguins

Still, there are other penguins that also have voices like braying donkeys, so that name doesn't characterize it well enough. Yet another name for these penguins is 'Blackfooted Penguin' but this is not helpful at all. Several other penguins have black or blackish feet. The most noticeable feature of this penguin, if you get a good look at it, is the horseshoe-shaped black band around its breast and belly. There are four penguins that have bands like these, constituting the genus Spheniscus, and this is the only one that occurs in Africa, making confusion unlikely. Two other banded penguins occur in South America and its waters, while one occurs in the Galapagos Islands – another tropical penguin that takes advantage of cold ocean currents. None of the banded penguins actually live in Antarctica. The genus name is derived from the Greek word 'sphenus' which means 'wedge' and refers to their streamlines shape when underwater. The African penguin's species name 'demersus' is Latin and means 'plunging', referring to its diving.

A Penguin's Life

Like all penguins the African penguin is flightless. Its wings have been heavily modified into flat flippers that are great for swimming. Indeed, what penguins do can be said to be flying underwater. To fly in the air a wing needs to have a very large surface area and needs to weigh very little. But a wing like that will be very cumbersome in water, generating too much drag and not being rigid enough. Because water is so much denser than air, a wing can be quite small and yet move enough water for effective underwater propulsion. Penguins can swim very fast, flapping their flippers rapidly and using their tails and webbed feet for steering. African penguins can swim out as far as 100 km/40 miles from the nearest land while foraging, and dive to a depth of 130 m/yards. Penguins can stay at sea for five days, sleeping while floating on the waves.

But being flightless leaves a penguin very vulnerable to predators on land. African penguins are unlucky in that the continent of Africa features a great many predators large enough to make a meal of them! Consequently they don't come on land much … but they have to, to breed. So, the penguins will nest either on small offshore islands or on small rocky regions where predators can't easily get at them. Their colonies are therefore very dense because there are not many such suitable areas available. They have benefited from the human reduction in land predators; one of their current breeding sites is Boulders Beach near Cape Town. Here tourists can approach quite close to the penguins, but are not allowed actually on the beach where they breed.

In South Africa, the penguins breed mostly in autumn, but in Namibia they breed mostly in summer. They are monogamous, forming pairs that use the same nesting sites year after year. Breeding season is when the male penguins will make the most of their braying voices! In what is called the 'ecstatic display' the male will start by standing erect and stretching his head and bill to the sky. He opens his bill and lifts his flippers high. Then he first silently throbs his breast as if to prepare his bray beforehand. Then at last he manages to 'free' it and it trumpets forth from his throat! While braying he will also twitch his flippers back and forth. This seems to be infectious, because when one penguin does it nearby penguins also tend to start doing it! So an entire colony can become a very noisy place.

Their 'nests' are very simple. They will dig a burrow if the soil allows; in places where they have been breeding for very long periods, there will be an accumulation of their droppings, that is to say guano, that is thick enough for them to excavate quite deep burrows in it. But in places where humans have been harvesting this guano they are often left having to dig in the sand, which is a lot less 'diggable' than guano. This leaves the chicks exposed, and in the sweltering sun they might then overheat. Penguin parents might scrape out a hollow beneath boulders or bushes that can provide some shade, if these are available. The burrow is lined with seaweed and bits of other vegetation, feathers, and pieces of bone.

The female penguin lay two eggs, or sometimes only one, rarely three. Both she and the male incubate the eggs in turns, and after the chicks hatch, take turns to forage and bring food to them; for the first month of their life the chicks will be guarded constantly by either one or the other parent, but then they will join a 'crèche' of similar-aged chicks that find safety in numbers, leaving both parents free to catch food for the chicks and for themselves. The chicks have bluish- to brownish-grey down that's darker on the back and lighter on the belly. They fledge in two to four months, depending on food availability. Then the chicks head out to sea, only returning to their birth spots in a year or two, to moult into their adult plumage. When moulting, penguins can't swim, so they have to complete the entire process, which might take twenty days, 'stranded' on land, and have to survive on stored fat reserves.

Although penguins live in cold to very cold regions, they are still birds, and have to maintain a constant warm internal temperature. The African penguin has a problem opposite to that of the Antarctic penguins – while they need to take care to stay warm, it has to take care not to become too hot when out on land under the blazing African sun. When you look at its face you'll see it has an area of bare, pink skin around its eye. This skin contains blood vessels. By expanding the blood vessels in this area, the penguin can radiate and so shed some of its inner heat to the outside air, helping it keep cool.

Apart from the band on its belly and breast and the pink patch over its eyes, the African penguin shares the black above/white below colour scheme with the majority of other penguins. This, too, is functional. It is called 'countershading'. If you're in the ocean and looking at a penguin from below, you'll see its white belly – but actually because all the light comes from above, it will not stand out much against the uniformly light background. If you look at it from above, you'll see its dark back, but again because the deep, dark waters are below, it will not stand out much then either. So predators like sharks or seals will not easily see the penguin unless they're quite close.

Cuddly, but Not so Small

Although people don't often realize it, penguins are among the largest of all birds. Their bodies being very compact, they are heavier than they look. The African penguin reaches a bodyweight of 3.6 kg/8 lbs, putting it among the smaller penguins. The Emperor penguin of Antarctica is the largest living species, reaching a weight of 45 kg/100 lbs; only ostriches, emus and cassowaries grow heavier than this. In the past there were much larger penguins, some standing as tall as a human and weighing 90 kg/200 lbs.

Dwindling Penguins

African penguins used to occur in huge numbers. Even though the islands off Africa's southern and western shores are few and small, penguins have been nesting on them in vast numbers … Dassen Island alone, only about a square mile/2.7 square km in area, has in the past hosted about a million and a half of them! But penguin numbers have plummeted, and mainly due to human interference. They've not been persecuted much directly, but guano gathering has caused disturbances of their nesting regions and as mentioned above actually made it harder for them to excavate their nests. Humans have also gathered their eggs commercially at a time, but this is no longer done. The main human threat to them today is competition for their food source! The fish-rich Benguela stream is very attractive to fishermen and used to support a massive pilchard fishery. As a result of this, pilchard populations collapsed. This caused the penguins great harm since they too preferred pilchards! But now the penguins are forced to eat anchovies most of the time, and these are not quite as nutritious, meaning the penguins have to catch more to get enough food, and they also need to swim farther to catch them. But now humans are catching the anchovies as well!

Yet another threat and the one people seem to find most disgusting is that of oil spills. This only happens every now and then, but when it does, huge numbers of penguins get oiled and may die of cold (oily feathers are robbed of insulating properties) and/or poisoning if people don't catch and clean them.

The result of all this is that there live only one tenth the number of African penguins today that there lived two hundred or so years ago.

But people do pity the penguins! In the year 2000 the oil tanker MV Treasure sank between Robben and Dassen Islands, oiling thousands of penguins. Volunteers with financial help from international as well as South African conservation organisations rounded up and cleaned oiled penguins; unoiled penguins were caught and released far away in clean waters so that the spill could be cleaned up by the time they'd swum back. Some of the removed penguins were radio-tracked and so provided data on penguin movements. The displaced birds generally took one to three weeks to swim back. The full rescue and rehabilitation project took three months and was the largest animal rescue in history.

Colours of Wildlife Archive

Willem

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