BackgroundHuman-predator conflicts are directly or indirectly threatening many species with extinction. Thus, biologists are urged to find simple solutions to complex situations while avoiding unforeseen conservation outcomes. The provision of supplementary food at artificial feeding sites (AFS) is frequently used in the conservation of scavenger bird populations currently suffering from indirect poisoning, although no scientific studies on its effectiveness have been conducted.Methodology/Principal FindingsWe used a long-term data set of 95 individually marked birds from the largest European core of the endangered bearded vulture (Gypaetus barbatus) to test the long-term effects of specific AFS for bearded vultures on their survival rates (by CMR models) and population dynamics (by Monte Carlo simulations) in an area where fatalities derived from illegal poisoning and the use of other toxics like veterinary drugs have increased over the last several years. Our data support the positive relationship between the use of AFS and survival. However, contrary to theoretical predictions (e.g. high and more stable adult survival among long-lived species), the use of AFS increased only survival of pre-adults. Moreover, AFS buffered the effects of illegal poisoning on this age-class, while adult survival decreased over years. Our simulations predicted a maximum value of extinction probability over a time horizon of 50 years. Population projections run with survival rates expected in scenarios without poisoning predicted the situation of least conservation concern, while including only AFS can maintain a large floater surplus that may delay population decline but fails to reduce poisoning risk among adults.Conclusions/SignificanceAlthough AFS are not effective to save bearded vultures from an expected population decline, they delay population extinction and can be a useful tool for prolonging population viability while combating illegal and indirect poisoning. The eradication of different sources of poisoning is of top priority to ensure the long-term viability of this and many other species.

SummaryWe analyse the causes of mortality for the Bearded Vulture in Europe. Shooting (31%), intentional poisoning (26%), collision (18%) and unintentional poisoning (12%) were the most important causes of mortality. No differences were found between sexes or age classes (nonadults and adults) for any of the causes of death. When the four main categories of mortality were grouped in periods of 3 years from 1986 (coinciding with the species' reintroduction to the Alps) to 2006, mortality showed significant temporal variation. The results suggest that while the number of collision/electrocution deaths has remained stable or increased slightly, the number of cases of shooting has declined during the last 6 years, while at the same time intentional and unintentional poisonings have increased. We found substantial differences between causes of mortality recorded for birds located by chance (75% related to shootings and collisions with powerlines) and radio-tagged birds (86% related to intentional and unintentional poisoning), suggesting biases in methodology for monitoring mortality. The results suggest that human persecution continues to be the main factor contributing to unnatural mortality for European Bearded Vultures. Future management actions should concentrate on the creation of protocols for the collection of carcasses and detailed analyses to determine and mitigate anthropogenic sources of mortality.

Origin of Red Plumage in Bearded Vultures Free-ranging adult bearded vultures, Gypaetus barbatus, typically have a rich orange colour on their underparts, neck and head. Wild birds, however, vary considerably in coloration and captive birds have a pure white ventral plumage. Rufous birds are the most usual colour morph throughout the range of the species, except in the small populations of the Mediterranean islands of Corsica (Thiollay 1968) and Crete (Xirouchakis 1998), where white birds are common. The origin of the coloration has been debated since at least the 19th century (Berthold 1967 and references therein). It was once attributed to carotenoid pigments (Clancey 1968), which are responsible for red, yellow and orange colours in other species (Brush 1990). We now know, however, that the orange colour comes from soils stained with iron oxide (Berthold 1967; Brown & Bruton 1991; Houston et al. 1993). Ferruginous colours are not exclusive to bearded vultures: many bird species, mostly waterfowl and cranes (Kennard 1918; Höhn 1955), have traces of iron oxide in their plumage. The bearded vulture, however, is the only avian species known to dye its plumage from soils to such an extent (Houston et al. 1993) and to do so deliberately (Frey & Roth-Callies 1994; see below). Early doubts on the origin of the bearded vulture's coloration (e.g. Clancey 1963) were also based on the lack of observations of bearded vultures bathing in red soils. In a 3-year study, which included the intensive tracking of radiotagged birds with rufous coloration, Brown (1988) often observed individuals bathing in water free of iron oxides, but never saw the birds deliberately rubbing themselves on red soils. Brown (1988) and Brown & Bruton (1991) suggested that staining was acquired passively, with no specific behaviour, when vultures came into contact with iron oxide deposits in places where they perched or at nests. This hypothesis, however, was questioned when captive white birds were provided with damp red soils (Houston et al. 1993; Frey & Roth-Callies 1994). The birds rubbed their bellies and heads in the soil, thus developing the characteristic deep rufous colour of wild birds. The behaviour pattern was different when birds bathed in water or in damp red soils. In the first case, they plunged into the water and then just shook the soaked plumage. However, when bathing in red soil, the bearded vultures rubbed themselves against the substratrum and preened the plumage for up to 1 h. The birds first transferred the damp mud that adhered to the ventral area to the shoulders and upper back with the beak and talons. Then the head was swung repeatedly between the shoulders and back, which soon acquired the orange colour. Nothing is known about bathing frequency in the wild, but captive birds offered new red soil every 2 weeks tended to use it immediately (A. Llopis, personal communication). Still another argument against the passive acquisition of the ferruginous colour is that large, white birds of prey that often perch and breed in the ...

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.

We present data from an extensive study of Bearded Vulture Gypaetus barbatus breeding biology in the Pyrenees from 1992 to 1999. Average laying date was 6 January (range 11 December to 12 February, n = 69) with no significant differences between years. Eighty per cent of clutches were of two eggs ( n = 20) and average incubation was 54 days (range 52-56, n = 14). Hatching occurred on average between 21 February and 3 March (range 5 February-7 April) and the first and last chicks fledged in 21-27 May and 20 July, respectively. The average chick age at fledging was 123 days (range 103-133, n = 20). Bearded Vulture density increased significantly during the study period. Breeding success and productivity declined apparently as a consequence of the increase in the percentage of breeding failures during incubation and chick rearing, most during the hatching period. The factors that may determine breeding failure and the decline in breeding performance are analysed and management recommendations for more effective conservation measures are discussed.