Egyptian Vultures Neophron percnopterus and Ostrich Struthio camelus eggs: the origins of stone‐throwing behaviour

Experiments were carried out on wild and hand‐reared Egyptian Vultures to investigate the origins of the stone‐throwing this species uses to break into Ostrich eggs. There was no evidence of cultural transmission for stone‐throwing through copying experienced birds. A naïve captive‐reared bird threw stones once an Ostrich egg had been linked with a food reward. The origins of aimed stone‐throwing are probably related to the unaimed throwing of small eggs, since the actions are similar, and all tested birds strongly preferred to throw rounded or egg‐like stones, rather than jagged ones, at Ostrich eggs.