Adélie penguins

Why these birds are dependent on Antarctica staying the way it is

robably the second most numerous of all penguin species, Adélie penguins are found and breed right around the coast of Antarctica and on a very few sub-Antarctic islands, with the biggest colonies being in the Ross Sea, East Antarctica and on the Antarctic Peninsula.

They feed almost exclusively on Antarctic krill, 6cm-long crustaceans believed to be the most abundant animal species on the planet in terms of their biomass, and occasionally Antarctic silverfish. In addition, recent research we have carried out suggests jellyfish may play a not insignificant part in their diet as well.

The most recent estimate puts the population at roughly 3.8m pairs, or 7.6m breeding individuals, a number that is drastically different from the mid-1990s figure of 2.4m pairs. There aren’t necessarily more birds, however: the higher figure is a result of using satellites to count colonies (by spotting guano stains), enabling researchers to find previously unknown colonies.

But while numbers in the peninsula are falling, those in the rest of the continent are either stable or rising.

The failure of a colony of more than 40,000 Adélie penguins on Petrel Island, in East Antarctica (news widely covered by the press) was actually caused by, among other factors, too much sea ice cover, which restricted the parents’ access to the sea and hence their ability to feed their chicks rapidly and regularly.

While this has no direct effect on the species as a whole, it does show how a large and healthy colony can be drastically affected by sudden changes to the environment, and it indicates that, even though common, this species may be more fragile than their sheer numbers suggest.

In the long term the future of Adélie penguins rests entirely on the health of the Antarctic ecosystem – if sea ice starts to melt in any significant way it will remove the habitat for their prey and the population will decrease.

IF SEA ICE STARTS TO MELT IT WILL REMOVE HABITAT FOR THEIR PREY.”

Adélie penguins are among the most successful seabirds on Earth but their breeding fortunes can be affected by changes to the environment, as a recent case showed.