blue-footed booby, i once watched a documentary on them, apparently they only keep one of the baby birds , all the others get pushed out of the nest to die. They then proceeded to eat their dying offspring. It was horrifying.
Blue-footed Boobies by nytimes: Biparental care is the rule among boobies, but longtime mates have perfected the art of symmetry and turn-taking. They spend the same time brooding and feeding the young, and expend the same physical effort as seen in measures of blood cells and body mass. #Birds #Parenting