Brood Reduction and Parental Infanticide — are the White Stork Ciconia ciconia and the Black Stork C. nigra exceptional?

Abstract

Brood size in birds is reduced through fatal starvation, siblicide or parental infanticide (killing of own offspring). Both Black and White Storks were observed practising facultative parental infanticide. In the White Stork parents regurgitate large amount of food consisting of many small items on the nest bottom. Chicks pick up food themselves, trying to eat as quickly as possible. No aggression among chicks is observed. As a result monopolisation of food does not occur and elimination of the weakest chick is very ineffective. Sometimes parent storks accelerate brood reduction by killing some of the offspring. Surprisingly, although parental infanticide is a quick and efficient method of brood reduction it is rarely observed, even in species practising it.