Diet and food preferences of the endangered Bearded Vulture Gypaetus barbatus: a basis for their conservation

Abstract

The Bearded Vulture Gypaetus barbatus population in the Pyrenees is managed using feeding 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 principally 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.

Dietary shifts in two vultures after the demise of supplementary feeding stations: consequences of the EU sanitary legislation

“…Consequently, it can be predicted that the growth of Iberian griffon vulture populations could end in the shortterm and even begin to decline in the long-term. Breeding counts carried out in northern Spain during 2007 and 2008 indicate this trend (Margalida et al 2009). …”

“…The scarcity of the main food resources exploited by the griffon vultures (predictable large carcasses) would lead to an increase in indirect competition with subordinate species for small and medium-sized carcasses, in a process similar to the hyperpredation observed in predator-prey systems (Courchamp et al 2000). In the Iberian Peninsula the carcasses of wild rabbits are heavily exploited by facultative predators and carrion-eaters (Delibes-Mateos et al 2008) and for some threatened species like the Egyptian vulture, the cinereous vulture (Aegypius monachus) and the bearded vulture (Gypaetus barbatus) constitute an essential part of the diet during the breeding period (Hiraldo 1976;Donázar and Ceballos 1988;Margalida et al 2009). In a field experiment carried out during 2005 and 2006, when the availability of large carcasses was still high, we observed that 30% of the wild rabbit carcasses were consumed by griffon vultures, which displaced other species like Egyptian vultures, red kites (Milvus milvus), black kites (Milvus migrans), marh harriers (Circus aeruginosus), common European buzzards (Buteo buteo), and common ravens (Corvus corax).…”

“…On the contrary, other scavengers are more polyphagous and, although they also exploit large carcasses, they invariably consume a number of small and medium-sized prey (Hiraldo et al 1991a;Mundy et al 1992;Travaini et al 1998). When several species concur at the same carcass, coexistence is made possible on the basis of resource partitioning, involving facilitatory and competitive processes still not well understood and apparently dependent on constraints linked to the species' life-history strategies and local conditions inherent to each carcass (Kruuk 1967;Wallace and Temple 1987;Mundy et al 1992;Margalida et al 2009). Facing scarce resources, competitive displacement may appear to permit the monopolization of the food source by the most aggressive (and eventually abundant) species (Hiraldo et al 1991b).…”

“…Given the scenario of a global vulture crisis (Koenig 2006), it is remarkable that the Iberian Peninsula and in particular, Spain, still holds the largest populations of avian scavengers in Europe and probably in the Old World (BirdLife International 2008;Margalida et al 2009). This is the result of both legal protection and high food availability.…”

The Pied Crow (Corvus Albus) Is Insensitive to Diclofenac at Concentrations Present in Carrion

“…vultures to protect the remaining populations on the Indian subcontinent, it is equally important to recognize risks to worldwide populations of various species of vultures and other avian scavengers. The latter group of birds is probably equally at risk of accidental toxicity as many countries (Namibia, Spain, India, Italy, Israel) have introduced ''vulture restaurants,'' where colonies are artificially fed through routine placement of carcasses (Meretsky and Mannan 1999;Bamford et al, 2007;Gilbert et al, 2007;Cortes-Avizanda et al, 2009;Gustin et al, 2009;Margalida et al, 2009). Hence, if any other NSAIDs (e.g., carprofen, flunixin meglumine, phenylbutazone, tolfenamic acid, meclofenamic acid, and ibuprofen) were to prove as toxic as diclofenac and ketoprofen, these vulture populations might also be at risk.…”