The Adelie is one of just two truly Antarctic species of penguin (the other being the very different Emperor). Named by the 19th century French explorer Jules Dumont D'Urville after his wife, Adelie penguins form their breeding colonies, or rookeries, on ice free islands or beaches close to the coast of Antarctica and cross the sea ice to feed in the sea. They feed on krill and small fish. Adelies are black and white with a white ring around their eyes which is more pronounced in the mating season. They are about 18-24 inches in height.
The breeding season starts in October/November. Two eggs are generally laid although one is usually much bigger than the other. The smaller egg is discarded and the parents share the incubation duties until the eggs hatch in late December (in the austral summer). The parents share the feeding of the newly hatched chicks, each in turn crossing the pack ice to the water edge to feed on krill. They then return to the nest site and feed their chick by regurgitating their recent feed into the chicks throat. In common with other penguin species, an adult will only feed its own chick so if a misfortune befalls the adult at sea (eg leopard seal), the chick will starve to death. Chicks are in danger from skuas. Adelies are often to be seen on the pack ice and their highly polished fronts help them with their preferred method of travelling across the snow - tobogganing. Adelies can display agressive behaviour during the mating season or when confronting predators. At these times they can raise their head feathers into an occiptal crest which can be seen in some of the pictures below.
In these pictures you can see a small rookery on an island near near Davis Station on the far side of Antarctica and Adelies on the sea ice nearby (2003). Also are pictures from a larger rookery at Brown Bluff on the Antarctic peninsula (2008).
Even in the summer, Adelies might have to endure very harsh weather conditions as blizzards and strong winds can send the effective temperature plummetting. In these pictures (2011), taken from the Southernmost penguin rookery in the world (of any species), one can see how effective is the layer of blubber and thick feather insulation because the snow on these penguins does not melt.
Here is a short (5 minute) film showing Adelie penguins on the sea ice in Eastern Antarctica and in a rookery at Brown Bluff near Snow Hill Island in the Antarctic Peninsula.