Siblicide
![A Nazca booby (Sula granti) with a chick and egg. When the second egg hatches, any siblings present will almost certainly kill their younger brother or sister.](/Images/godic/202502/11/Nazca_booby_chick_and_egg5902.jpg")
Siblicide (attributed by behavioural ecologist Doug Mock to Barbara M. Braun) is the killing of an infant individual by its close relatives (full or half siblings). It may occur directly between siblings or be mediated by the parents. The evolutionary drivers may be either indirect benefits for the genetic viability of a population or direct benefits for the perpetrators. Siblicide has mainly, but not only, been observed in birds.