All of the Suliformes employ a regurgitative strategy to feed their young. In some species — such as the blue-footed booby, masked booby, and the Nazca booby — a brood hierarchy exists, in which the older chick is fed before the younger, subordinate chick. In times when food is scarce, siblicide may occur, where the dominant chick kills its younger sibling in order to sequester all of the resources of the parents. Penguins chicks are fed regurgitated food by both parents. Researchers found that the practice may potentially cause metabolic alkalosis in certain penguins.
