Fewest eggs per year for a penguin

The two species of great penguin – namely, the emperor penguin Aptenodytes forsteri of Antarctica and the king penguin A. patagonicus of southernmost South America and several northern subantarctic islands – each lay only a single egg per year. All other species lay two. However, the great penguins' eggs are large with thick shells for protection purposes. In the emperor penguin, 15.7% of the egg's total weight is its shell, which helps very considerably to minimise breakage of what, as a single egg per penguin couple per year, is a precious commodity for its species' survival.