Lesser Spotted Eagle (Aquila pomarina) Science Article 2
Detailed observations were made of Cainism in a Lesser Spotted Eagle’s (LSE) nest, whereby this procedure generally leads to the death of the second chick a few days after hatching. The time-lapse between hatchings amounted to two and a half days (60 hours). At the time of hatching the chicks weighed 64 und 58 g respectively. During the first and second days after the second chick (Abel) hatched, no signs of Aggression could be observed and herb chicks received a liberal supply of food. On the third day, however, herb chicks were strenuously fighting, with Abel being the first to attack. On the fourth day the female was displaying an unmistakable tendency to favour the older chick (Cain), which clearly held a stronger attraction for her. On one occasion the feeding by the female abruptly ended even though Abel was still actively begging for food. On this day Abel was indeed still given food, but its begging and its own attacks were, however, very haphazard. At four days old Abel weighed 12 g less than it did on hatching. This chick probably died the next day, even though there was an abundance of food in the nest.
Meyburg, B.-U. (2001), ornithoecologica 4: 269-278