The Nazca Booby (Sula granti), is a species of booby found in the eastern Pacific ocean, mainly on the GalÃ¡pagos Islands and Clipperton Island. The northernmost limit of its breeding range is Baja California where it can also be spotted on the Revillagigedo Islands. Once regarded as a subspecies of the masked Booby, it is now recognized as a separate species.
Nazca boobies are known for practicing habitual siblicide. They lay two eggs, several days apart. If both eggs hatch, the elder chick will push its sibling out of the nest area, leaving it to die of thirst or cold. The parent booby will not intervene and the younger chick will inevitably die. It is believed that two eggs are laid so that one remains an insurance in case the other gets destroyed or eaten by other birds, or the chick dies soon after hatching.