Ibis (2009), 151, 235–243 © 2009 The Authors Journal compilation © 2009 British Ornithologists’ Union Blackwell Publishing Ltd Diet and food preferences of the endangered Bearded Vulture Gypaetus barbatus: a basis for their conservation ANTONI MARGALIDA, 1 * JOAN BERTRAN 1 & RAFAEL HEREDIA 2 1 Bearded Vulture Study and Protection Group, Apdo. 43, E-25520, El Pont de Suert, (Lleida), Spain 2 Camino del Túnel, 198, Somió, Gijón, E-33203, Spain The Bearded Vulture Gypaetus barbatus population in the Pyrenees is managed using feed- ing stations to increase breeding success and reduce mortality in the pre-adult population. Nevertheless, very little quantitative and qualitative information has been published on such basic aspects of the species’ ecology as feeding habits and dietary preferences. This study investigated both aspects through direct and unbiased observation of breeding Bearded Vultures during the chick-rearing period. Bearded Vulture diet comprises mammals (93%), birds (6%) and reptiles (1%), with medium-sized ungulates (mainly sheep/goats) the most important species in the diet (61%, n = 677). Prey items were not selected in proportion to their availability, with the remains of larger species (cows and horses) being avoided, probably due to the variable cost/benefit ratios in handling efficiency, ingestion process and transport. There is no relationship between the proportion of sheep limbs in the diet and the proximity of feeding stations, suggesting that these sites are probably less important for breeding adults than for the pre-adult population. On the other hand, diet specificity seems related to productivity, with territories with greater trophic breadth being those with higher fecundity. Bearded Vultures prefer to eat limbs, although meat remains (provided princi- pally by small mammals) can play an important role in guaranteeing breeding success during the first few weeks after hatching. The management of carrion provided by animals that die naturally in extensive livestock practices and the remains of wild ungulates which have died naturally or by human hunting, are important conservation tools for the Bearded Vulture and other carrion-eating species. Keywords: breeding success, feeding stations, prey selection, trophic diversity, supplementary feeding. Knowledge of dietary preferences may have important implications for the conservation of threatened species by helping to increase population distribution (e.g. the management of species that depend on the application of supplementary feeding programmes, see Boutin 1990, Jones 2004), improve breeding performance (González et al. 2006) and reduce or eliminate human-induced mortality factors related to their feeding habits (e.g. conflicts with the rearing of livestock or hunting practices, see Thirgood et al. 2000, Marquiss et al. 2003, Palma et al. 2006, or toxicosis and illegal poisoning, see Berny 2007, Hernández & Margalida 2008). In addition, observed prey preferences may be limited by the availability of optimal prey species (Hayward et al. 2006), and such species may be important for conservation projects. Thus, detailed knowledge of prey preferences helps to identify problems prior to new projects allowing managers to improve their success rate. Recently, conservationists have been alarmed by dramatic declines of vultures related to diclofenac poisoning in Asia (Green et al. 2004, Oaks et al. 2004), and more recently in Africa, too (Thiollay 2007). Their specific feeding habits based on dead animals make them very vulnerable to mortality due to toxicosis, and the use of supplementary feeding stations has been considered one of the most useful management techniques for recovering their popula- tions, although the effects and efficacy of this strategy *Corresponding author. Email: margalida@inf.entorno.es