Why do the masked boobies kill their siblings?

Masked boobies engage in sibling aggression, often resulting in the death of one chick, primarily as a survival strategy. This behavior, known as "siblicide," occurs because the parents typically only have the resources to successfully rear one chick to maturity. The stronger chick may kill its weaker sibling to reduce competition for food and parental care, ensuring its own survival in a challenging environment. This strategy ultimately enhances the survival chances of the remaining chick.