There's also siblicide (https://en.wikipedia.org/wiki/Siblicide#In_birds https://en.wikipedia.org/wiki/Siblicide#In_birds): > In these three booby species, hat

There's also siblicide (https://en.wikipedia.org/wiki/Siblicide#In_birds https://en.wikipedia.org/wiki/Siblicide#In_birds): > In these three booby species, hatching order indicates chick hierarchy in the nest. The A-chick is dominant to the B-chick, which in turn is dominant to the C chick, etc. (when there are more than two chicks per brood). Masked booby and Nazca booby dominant A-chicks always begin pecking their younger sibling(s) as soon as they hatch; moreover, assuming it is healthy, the A-chick usually pecks its younger sibling to death or pushes it out of the nest scrape within the first two days that the junior chick is alive. Blue-footed booby A-chicks also express their dominance by pecking their younger sibling. However, unlike the obligately siblicidal masked and Nazca booby chicks, their behavior is not always lethal. A study by Lougheed and Anderson (1999) reveals that blue-footed booby senior chicks only kill their siblings in times of food shortage.