The nest is often no more than a slight hollow in the ground, but some penguins, especially the Adelie penguins Pygoscelis adeliae , collect stones, with which they bank the nest round. One or two eggs are laid, and both birds, but chiefly the male, attend to their incubation. Both parents are very devoted to the young, one always staying to guard them, the other bringing them sea crustaceans and other small animals, which the young take by pushing their beaks far down the parent's throat. The young gather in groups while the parents are foraging for food. When the parents return, the chicks often have to chase for food, with the stronger chick being fed first.
Zoologists blame over-fishing, particularly by large trawling fleets.
Species Most species are confined to the colder regions, and large rookeries have been found at very low latitudes. Its plumage is dark slate on the back and white on the underparts, with yellow spots on the head. Its single annual egg is brooded by the male in the warmth of a flap of his body skin, so that it rests on his feet. Males and females walk over the ice to the breeding ground, often many miles from the sea. When the egg is laid, the female passes the egg to the male, and returns to the sea to feed.