Macaroni penguin once together at the nest site and at changeover of incubation shifts. In the 'ecstatic display', a penguin bows forward, making loud throbbing sounds, and then extends its head and neck up until its neck and beak are vertical. The bird then waves its head from side to side, braying loudly. Birds also engage in mutual bowing, trumpeting, and preening. Monitoring of pair fidelity at South Georgia has shown around three-quarters of pairs will breed together again the following year. Adult macaroni penguins typically begin to breed late in October, and lay their eggs in early November. The nest itself
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