Detailed observations were made of Cainism (fatal Cain-and-Abel struggle) in a Lesser Spotted Eagle's (LSE; Aquila pomarina) nest in Slovakia from a hide in which the second chick could be closely observed from hatching to death. At a second eyrie in Germany a remotecontrolled video camera was used to record on tape the events leading up to the death of the second chick. In a third case in which the strife between the siblings was studied, both chicks had clearly passed the age at which the second chick has usually perished. Here observations were conducted for several days from a blind.