Every year, April 25th marks World Penguin Day, a chance to celebrate these popular and charismatic birds. There are 18 species of penguin, and all are found in the southern hemisphere. These iconic flightless birds range from the large, well-known emperor penguin to the tiny, aptly name little penguin, and all are well adapted to the environments in which they live.
To celebrate World Penguin Day, here at ARKive we thought we would celebrate all things penguiny by taking a closer look at these fascinating birds.
Icon of the Antarctic
At over one metre tall, the emperor penguin is the largest penguin species. One of the most iconic animals of the Antarctic, this hardy bird is well adapted to the cold, with a relatively small head, beak and flippers to reduce heat loss, and layers of tightly packed, scale-like feathers to keep it warm and dry. Like other penguins, it also has a thick layer of fat that acts as insulation and an energy store. Male emperor penguins incubate a single egg throughout the harsh Antarctic winter, when temperatures can drop to an incredible minus 60ºC. The males balance the eggs on their feet, and huddle together to keep warm.
Coping in the heat
Although typically associated with cold environments, not all penguins live in the Antarctic. The African penguin breeds in southern Africa, where it has to deal with potentially high temperatures. To protect its nest against the heat, the African penguin often nests in burrows or in the shade of boulders or bushes. The most northerly penguin species is the Galapagos penguin, which is found near the equator.
All penguins are superb swimmers, with streamlined bodies and flipper-like wings which give them great speed underwater. Penguins can cope with long, deep dives, and some species spend as much as 75% of their lives at sea. Compared to flying birds, which have light, hollow bones, penguins have heavy, solid bones which aid diving. Legs set far back on the body help penguins to steer underwater, but mean they walk clumsily on land.
Well-dressed water birds
Penguins are characterised by their distinctive black and white colour patterns. Known as ‘countershading’, this pattern provides camouflage underwater, helping the penguin to avoid detection by predators and prey. When seen from above, the penguin’s dark back blends in with the dark ocean depths, and when seen from below its white belly blends in with the light from the sky. Penguin species are most easily told apart by the distinctive patterns on their head and neck, and some species even sport quite colourful hairdos!
Penguins often form huge breeding colonies that may number hundreds of thousands of breeding pairs, and the stains left by the droppings of so many birds can sometimes be seen from space. Penguins usually form monogamous pairs in each breeding season. Nesting sites vary between species, and can include sea ice, rock, beaches, or even coastal forest, in the case of the Fiordland crested penguin.
Penguins use their great swimming ability and speed underwater to catch a variety of fish, squid and crustaceans, including the shrimp-like krill. Amazingly, penguins are able to drink seawater when at sea, as they possess glands which filter excess salt from the blood, excreting it from the nasal passages in a concentrated salty fluid.
Penguins have a series of adaptations which help to reduce heat loss through the feet and prevent the feet from freezing when the bird is standing on ice. As warm blood enters the legs, it flows past cold blood returning from the feet. In this way, the blood entering the feet is cooled, reducing heat loss, and the blood returning to the body is warmed again. Penguins can also reduce blood flow to their feet in freezing conditions, and may tip back on their heels to minimise the area of skin in contact with the ice.
On land, penguins generally have few predators, although birds such as the southern skua may take their eggs and chicks, and adult penguins may also be attacked by the northern giant petrel. In the sea, penguins may be attacked by leopard seals and orcas.
Bad feather day
Like most birds, penguins moult once a year, replacing worn and damaged feathers to keep their plumage in top condition. However, unlike most other birds, which moult a few feathers at a time, penguins moult all their feathers in one go, as missing just one or two would affect their waterproofing and put them at risk from the cold. Before its annual moult a penguin puts on weight, building up fat reserves which allow it to stay out of the water while it waits for its new feathers to grow. During this time it can take on a decidedly scruffy appearance!
Really quite cool
Penguins are hugely popular birds and commonly appear in films, TV programmes and popular culture, being much loved for their comical appearance and upright, almost human-like walk. They are also hardy survivors, occurring in some of the most dramatic landscapes on the planet.
Unfortunately, humans have also had negative impacts on penguin populations, through pollution, overfishing, coastal development and the effects of climate change. The International Penguin Conservation Working Group is helping to promote penguin conservation and to draw attention to the threats facing penguins, and with various research programmes also underway there is hope that these iconic birds can be protected into the future.
Why not join in the World Penguin Day celebrations yourself? You can explore more penguin photos, videos and factfiles on ARKive, or make a penguin mask with our Penguin Diversity education module.
Or, get in touch and let us know which species of penguin is your favourite and why!
Liz Shaw, ARKive Text Author