This post was in progress when we lost our internet connection two weeks ago…
Adelie penguins nest along the Antarctic coastline in areas where persistent winds keep the rocks free of ice and snow. During the winter they migrate north to the edge of the winter ice, where they can still find some open water and a few hours of daylight. In spring they return to their breeding areas. The males are the first to arrive, establish territories, and build nests out of small pebbles.
The pebbles help to keep the eggs and chicks dry and warm, away from the spring thaw. They are thus considered of utmost importance, and Adelies will go to any length to collect as many pebbles as they can in as short a distance as possible. Sometimes this means stealing them directly from an unsuspecting or absent neighbor.
The females arrive shortly after the males, seek out their mate from the previous year (or find a new one if the previous mate is absent), and establish a pair bond. Once paired the two are able to recognize each other by voice. Within a few days they copulate, lay 1-2 eggs, and thus begin their annual nesting cycle. The males take the first incubation shift while the females go to sea to recuperate some of the energy lost in producing the eggs. The eggs hatch within about 30 days.
A great deal of energy is spent in defending the nest from pesky intruders: neighbors who walk too close to the nest, previous occupants who try to reclaim their lost territories, skuas out looking for a meal (some skuas specialize in eating penguin eggs and chicks), and penguin biologists such as ourselves.
Adelies also spend a considerable amount of time preening. Healthy, well-oiled feathers help to insulate them from the cold and maintain a hydrodynamic exterior.