25 April is World Penguin Day

Global warming has krill stocks running low – how are penguins reacting?

two penguinsClick to enlarge
Only five of the 18 penguin species live in Antarctica.
Source: Fritz Hertel/UBA

Penguins are to the South Pole what the polar bear is to the North Pole. All 18 penguin species live almost exclusively in the southern hemisphere, seven of which are in Antarctica and on sub-Antarctic islands. Besides their cold habitat, polar bears and penguins have another thing in common: they are under threat from global warming. A considerable amount of research has revealed sometimes dramatic losses in the numbers of penguins. These losses are due to the retreat of polar ice as a result of climate change, which is also responsible for smaller stocks of krill. Krill are tiny shrimp-like crustaceans which form the main source of food for penguins. If krill disappears penguins will eventually do the same.

The 25th of April is internationally recognised as World Penguin Day. Its origins lie in a curious situation: scientists at the American McMurdo station in Antarctica noticed that every year the Adélie penguins returned after months at sea to their breeding colony on land – every year on 25 April and to the same place, like clockwork. They declared the day their own holiday, and it has slowly become established worldwide.

Global climate change is giving penguins in Antarctica a hard fight. Based on many individual observations, researchers have recorded large-scale changes in the populations of different species of penguins for a number of years. Krill, a small crustacean only a few centimetres in size, is the main source of food for many penguins, fish and whales in Antarctica. The retreat of the sea ice in some locations has led to smaller krill stocks and when food disappears, penguins gradually follow suit.

Nevertheless knowledge is still lacking about the distribution of the different penguin species and the phenomenon of their population shifts on the vast southern continent. Antarctica covers an area of some 14 million square kilometres, is one and a half times the size of Europe and in parts very inaccessible. This is why scientific methods must be developed to carry out effective studies on the distribution of individual species across this vast area, something which can be done with satellite images. High-resolution images can determine the location and size of penguin colonies.

Using this method British researchers succeeded for the first time in 2012 in making a reliable estimate of the world population of emperor penguins. This large penguin breeds exclusively in Antarctica and on icy area on its offshore islands and is relatively easy to track, whereas penguins which breed on rocky terrain are more difficult to find. In the latter case satellite images are used to look for animal excrement (guano) which covers large areas of the ground where penguin colonies live. This trick makes it possible to gain an idea of the size of the colonies identified on the images. It is however necessary to verify these estimates by doing spot-check counts of penguin numbers on location, a job which in the meantime small drones are doing. The Federal Environment Agency has commissioned the ThINK company in Jena to do research in this area. The project's long-term goal is to develop a methodology for a system of international penguin monitoring.

Further information:

Unlike the Arctic, Antarctica is a continent surrounded by water. Because it is covered by an immense ice shield it remained virtually untouched for hundreds of years. However, a wide range of human activities have been taking place on the continent for a little more than a century now. After the age of discovery and whaling it has been chiefly researchers who are demonstrating an extraordinary interest in the white continent. The Antarctic Treaty was signed in 1959 banning territorial disputes and military activity on the continent. This is to ensure that Antarctica is used exclusively for peaceful purposes "in the interest of all humankind". The Protocol on Environmental Protection to the Antarctic Treaty entered into force in 1998 and requires the parties to the treaty to provide wide-ranging protection of the Antarctic environment and prohibits commercial mining activities. The Act implementing the Environmental Protocol (AUG) enacts the Protocol into German law and designates the Federal Environment Agency (UBA) as the responsible authority for its enforcement and monitoring.

Umweltbundesamt Headquarters

Wörlitzer Platz 1
06844 Dessau-Roßlau


  1. Nur fünf von insgesamt 18 Pinguinarten kommen in der Antarktis vor.
  2. Adeliepinguine sind eine der fünf Pinguinarten, die in der Antarktis brüten.
  3. Der Kaiserpinguin ist der größte seiner Art.
  4. Eselspinguine fühlen sich besonders entlang der Antarktischen Halbinsel wohl.