Despite the consensus among ecologists and conservationists of the importance of maintaining scavenger feeding patterns based primarily on natural prey sources, human-mediated feeding remains a widely used management tool for threatened wildlife. Thus, it is important to understand the key factors favoring certain species and age-groups at supplementary feeding sites. Through a detailed videomonitored experiment of carrion inputs at different locations in the Iberian Peninsula (home of .90% of European vultures), we assessed how variables related to weather, time, demography, management and alternative food availability influenced the occurrence patterns of different age-classes of vultures at feeding sites. The most threatened and less gregarious species (bearded vulture Gypaetus barbatus and Egyptian vulture Neophron percnopterus) attended to earlier inputs, thus reducing interspecific competition with the Eurasian griffon vulture Gyps fulvus. The bearded vulture was favored by a larger biomass supply at the feeding sites during the chick-rearing period, while the Egyptian vulture preferred frequent and abundant inputs. Non-adult cinereous vultures Aegypius monachus were favored at times of lower abundance of natural resources and in the densest networks of feeding sites, while adults preferentially attended sites with periodic inputs close to breeding colonies in areas with lower availability of other natural prey. Finally, the Eurasian griffon vulture showed a preference for continued and periodic inputs, and for feeding sites with numerous other feeding sites in the surroundings. Our results help to inform the management of supplementing food provision with the aim of enhancing its value to reverse the unfavorable conservation status of endangered species and to mitigate the negative effects of the current global threats impacting them.