SYNCHRONOUS HATCHING AND THE CAIN AND ABEL STRUGGLE IN THE BLACK EAGLE

Abstract

Summary Gargett, V. 1982. Synchronous hatching and the Cain and Abel struggle in the Black Eagle. Ostrich 53:147-150. An experiment was conducted to cause two Black Eagle Aquila verrreauxii chicks to hatch synchronously. There was ample food on the nest and the female offered it to both chicks, but the smaller chick, from the smaller second-laid egg, died. The greater reach of the chick from the first-laid egg enabled it to obtain more of the food offered, so that it gained weight. Its greater mass then enabled it to prevent its sibling from taking food. Both chicks showed aggression, but that of the heavier chick was more effective.