Macaroni penguin and giant petrels also take chicks and sick or injured adult birds. Female macaroni penguins can begin breeding at around five years of age, while the males do not normally breed until at least six years old. Females breed at a younger age because the male population is larger. The surplus of male penguins allows the female penguins to select more experienced male partners as soon as the females are physically able to breed. Commencing a few days after females arrive at the colony, sexual displays are used by males to attract partners and advertise their territory, and by pairs
Bird egg the shell immediately before laying, but this research shows coloration is an integral part of the development of the shell, with the same protein responsible for depositing calcium carbonate, or protoporphyrins when there is a lack of that mineral. In species such as the common guillemot, which nest in large groups, each female's eggs have very different markings, making it easier for females to identify their own eggs on the crowded cliff ledges on which they breed. Bird eggshells are diverse. For example: Tiny pores in a bird eggshell allow the embryo to breathe. The domestic hen's egg has around