Acquisition of food by fledgling Egyptian Vultures Neophron percnopterus by nest-switching and acceptance by foster adults

In a dense population of Egyptian Vultures Neophron percnopterus in northern Spain, nest-switching occurred between nearby nests. Fledglings obtained more feeds by intruding and pirating than by remaining in their own nests during the same period. Intruder fledglings showed the same behaviour with Foster adults attacked intruder fledglings significantly less than they attacked alien adults and immatures but more frequently than they attacked their own fledglings. Effective rejection behaviour by foster adults to intruders may not have evolved as Egyptian Vultures usually nest at lower densities than that found in the study area.