Behavior
Nazca Boobies are known for practicing obligate siblicide. Mothers lay two eggs, several days apart. If both eggs hatch, the elder chick pushes its sibling out of the nest area, leaving it to die of thirst or cold. The parent booby cannot intervene and the younger chick inevitably dies. Two eggs are laid so that if one gets destroyed or eaten, or the first chick dies soon after hatching, the second egg will produce an offspring.Adults that have failed to breed frequently seek out nestlings in their colony, and during those visits they often bite, preen and even try to copulate with chicks. The causes of this behavior are not fully understood.
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