Bearded Vulture Gypaetus Barbatus Research Articles

First cases of polygyny for the Bearded Vulture Gypaetus barbatus in the central Pyrenees

ABSTRACTWe report the first cases of polygyny for the Bearded Vulture Gypaetus barbatus in the central Pyrenees, Spain. Although polyandry is frequent in the study area (31.8% of all reproductive units in 2016), we only observed the occurrence of three cases of polygyny over the period 1994–2017. Polygyny in Bearded Vultures is possibly a consequence of habitat saturation.

Diet Composition of Four Vulture Species in Azerbaijan

We studied the diet of four avian scavenger species, the Griffon Vulture Gyps fulvus, Black Vulture Aegypius monachus, Egyptian Vulture Neophron percnopterus and Bearded Vulture Gypaetus barbatus in Azerbaijan, in the South Caucasus region, from 2008–2012. During these years, a total of 1861 remains were collected between May and July at nests of each of the four vulture species. The collected food remains belonged to 45 different animal species, including at least 24 species of wild mammals and eight species of domestic mammals. Diet composition of Griffon and Black Vultures differed greatly between years, consisting mainly of Domestic Sheep Ovis aries in 2008 and 2009, carnivores such as Grey Wolf Canis lupus, Golden Jackal Canis aureus and Red Fox Vulpes vulpes in 2010, and Domestic Horses Equus ferus caballus in 2011 and 2012. The diet of Egyptian Vultures was less variable across years, but generally consisted of a larger variety of wild animals, including Red Fox, Brown Hare Lepus europaeus caucasic...

The importance of the nutritive value of old bones in the diet of Bearded vultures Gypaetus barbatus

Vultures are central-place foragers and need to optimize their foraging behaviour to offset travel costs by increasing their energy gain. This process is more obvious in certain vulture species that do not feed their young by regurgitation and so must carry food items back to the nest. The Bearded Vulture Gypaetus barbatus is the only species with a bone-diet based. We analysed the chemical composition of bones and the age-related changes in their nutritive value to assess the differences in energy content between bones of differing age, body part and species. We found differences between specific anatomical parts, species and the age of the bones. Fresh bones contain 108% as much energy as fresh meat and, interestingly, dry bones retain 90% of the protein found in fresh bones. Dry femurs weighing 140 g retain enough protein to be comparable to 111 g of fresh meat, in energy terms. Compared to meat-eating species, the specialized osteophagous diet of the Bearded Vulture seems to have certain advantages. A better understanding of nutrient levels in food remains could help to improve theoretical foraging models, assist in conservation management, and even improve our understanding of the use of bones by early hominids.

Productivity of the declining Bearded Vulture Gypaetus barbatus population in southern Africa

Recent research has shown that anthropogenic influences are driving the abandonment of breeding territories in the declining southern African Bearded Vulture Gypaetus barbatus meridionalis population. Survival rates appear to be low (86% for adults) due to poisoning and collisions with powerlines, which are the primary causes of death from tracked birds. However, there is no information published on the population’s current productivity levels, and whether this may be a contributing factor in the declines of this population. This information is vital for a more holistic approach to the conservation of the population. In this study we use data from breeding territory surveys between 2000 and 2016 to estimate productivity for this population. Only around 54% ± 74% (17–91%) of pairs attempted to breed each year, and although nesting success for pairs attempting to breed was relatively high (0.75 ± 0.22; 0.44–1.00), this resulted in low productivity of only 0.42 ± 0.65 (0.28–0.67) young per pair per year. These results contrast with previous surveys, suggesting the productivity may have declined over the last three decades, principally due to many pairs not attempting to breed in each year. Understanding the factors influencing productivity amongst pairs could be useful to guide conservation actions.

European policies on livestock carcasses management did not modify the foraging behavior of a threatened vulture

Policy decisions have the potential to affect biodiversity conservation and modify, among other factors, animal demography, behavior and ecological processes. This became manifest in Europe in the past decade in light of the appearance of bovine spongiform encephalopathy (BSE). However, the obvious effects of policy decisions on foraging behavior are lacking. Here, we use data from a long-term study (1992–2015) of the ecology of the bearded vulture Gypaetus barbatus in the Pyrenees to assess whether or not the implementation of health policies in the period 2006–2011 really did affect this vulture's foraging behavior and breeding success. To test this, we used the frequency of nest changeovers (between 1992 and 2015) as a surrogate for the time invested in searching for and obtaining food. Additionally, between 2006 and 2015 we monitored the movements of 20 bearded vultures with GPS satellite transmitters. Our findings show no differences between annual home range sizes and/or the time used to search for food either before, during or after the imposition of health regulations. No differences between periods (during or after health regulations) were found in the use of supplementary feeding sites (SFS). An analysis of food available indicates that this similarity of use in different periods could be explained by the high habitat quality in the Pyrenees and the good availability of trophic resources. Our results suggest that diet plasticity and habitat quality compensate for the sudden effects of food shortages and so question the true usefulness of SFS in buffering a quantitative food deficit. We discuss the implications of these results from both ecological and conservation perspectives.

How to plan reintroductions of long-lived birds

Reintroductions have been increasingly used for species restoration and it seems that this conservation tool is going to be more used in the future. Nevertheless, there is not a clear consensus about the better procedure for that, consequently a better knowledge of how to optimize this kind of management is needed. Here we examined the dynamics of released long-lived bird populations (lesser kestrel, Falco naumanni, Bonelli's eagle Aquila fasciata, and bearded vulture Gypaetus barbatus) in object-oriented simulated reintroduction programs. To do that, number of young per year and number of years of released necessary to achieve a successful reintroduced population were calculated. We define a successful reintroduction as one in which when the probability of extinction during two times the maximum live-span period for the species (20, 50, and 64 years respectively) was less than 0.001 (P<0.001) and they showed a positive trend in population size (r>0.00). Results showed that a similar total number of young (mean 98.33±5.26) must be released in all the species in all the scenarios in order to get a successful reintroduction. Consequently, as more young per year are released the new population is going to be larger at the end of the simulations, the lesser the negative effects in the donor population and the lowest the total budget needed will be.

Insights into post-fledging dispersal of Bearded Vultures Gypaetus barbatus in southern Africa from GPS satellite telemetry

ABSTRACTCapsule: Fledglings progressively increase their home range size and ranging behaviour as they age.Aims: To examine the home range size and ranging behaviour of Bearded Vulture fledglings during the post-fledging dependence period and determine the onset of natal dispersal.Methods: Post-fledging movements of three individuals were investigated in southern Africa using global positioning system (GPS) satellite telemetry which enabled home range sizes and distances travelled from the nest to be calculated.Results: Fledglings increased their home range size from an average of 0.4–10 999 km2 (100% Minimum Convex Polygons) and 9.13–11 466 km2 (fixed 95% kernels) within the first six months post fledging. They also increased home range use as they aged with maximum daily distances travelled from the nest occurring between 98 and 136 days post fledging (when fledglings were aged between 222 and 262 days), after which time they dispersed from their natal area. Distances between fixes were highest during the dispersal period.Conclusion: GPS satellite telemetry allows us to accurately demonstrate how fledglings progressively increase and use their home ranges as they age and undertake pre-dispersive exploratory flights. Results confirm the notion that juveniles disperse at the onset of the following breeding season and suggest that dispersal occurs earlier in the southern hemisphere.

Parental investment in two large raptors breeding in a high prey density area

We investigated the breeding behaviour of Bearded Vulture Gypaetus barbatus and Golden Eagle Aquila chrysaetos between 2008 and 2011 in the Stelvio National Park (the Alps, Italy), which harbours one of highest densities of wild ungulates in the Alps. Parental care behaviours (incubation and chick brooding, nest attendance, changeover, food provisioning and nestling feeding) were recorded at nests of both species (four Bearded Vulture and 14 Golden Eagle pairs). Differences in investment between sexes and periods were found in both species: the time spent in incubation and nest attendance was higher in females and decreased with the progress of the breeding season (from incubation to post-hatching and to pre-fledging). A significant effect of the interaction between sex and period was also found. Compared to the literature, our results suggest a lower contribution by Bearded Vulture males, whereas Golden Eagle males spent more time in incubation and nestling brooding than reported. The higher investment shown by Golden Eagle males in our study area may be due to the high availability of live prey and ungulate carrion, which could allow males to spend less time in hunting, resulting in more time at the nest. Most changeovers for both species took place in the central hours of the day. No difference in food provisioning was observed between the sexes of the two species, consistent with information available for Bearded Vultures, but not for Golden Eagles. The patterns we found revealed a female-biased investment (unexpected for the Bearded Vulture), although males significantly contributed to nest behaviour, especially during the incubation period (unexpected for Golden Eagles). The large amounts of natural prey and carrion in the study area may contribute to the nest behaviour of these large raptors.

Spatial and temporal movements in Pyrenean bearded vultures (Gypaetus barbatus): Integrating movement ecology into conservation practice.

Understanding the movement of threatened species is important if we are to optimize management and conservation actions. Here, we describe the age and sex specific spatial and temporal ranging patterns of 19 bearded vultures Gypaetus barbatus tracked with GPS technology. Our findings suggest that spatial asymmetries are a consequence of breeding status and age-classes. Territorial individuals exploited home ranges of about 50 km2, while non-territorial birds used areas of around 10 000 km2 (with no seasonal differences). Mean daily movements differed between territorial (23.8 km) and non-territorial birds (46.1 km), and differences were also found between sexes in non-territorial birds. Daily maximum distances travelled per day also differed between territorial (8.2 km) and non-territorial individuals (26.5 km). Territorial females moved greater distances (12 km) than males (6.6 km). Taking into account high-use core areas (K20), Supplementary Feeding Sites (SFS) do not seem to play an important role in the use of space by bearded vultures. For non-territorial and territorial individuals, 54% and 46% of their home ranges (K90), respectively, were outside protected areas. Our findings will help develop guidelines for establishing priority areas based on spatial use, and also optimize management and conservation actions for this threatened species.

Corrigendum

Corrigendum

Optimization of supplementary feeding programs for European vultures depends on environmental and management factors

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 &gt;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.

The frequency distribution of lead concentration in feathers, blood, bone, kidney and liver of golden eagles Aquila chrysaetos: insights into the modes of uptake

Several cases of acute lead poisoning of golden eagles Aquila chrysaetos have been documented in the Alps. The question, however, remains how often golden eagles take up lead (once, chronically or episodically) and whether this uptake is in fatal or sublethal amounts. We approached this question by examining the level and frequency distribution of lead concentration in different tissues and in three segments of flight feathers in 41 golden eagles found dead, injured or moribund in the Swiss Alps. The frequency distribution of lead concentration in the blood, liver, kidney, wing coverts and shaft of flight feathers were all right-skewed. The highest values in blood, kidney and liver reached levels typical for acute fatal poisoning. In contrast, the frequency distribution of lead in bones was more symmetrical, but 71 % had bone lead concentrations >10 µg/g, which are considered elevated, and 29 % >20 µg/g, values often observed in cases of lethal poisoning. In 22 % of individuals, only one segment of a flight feather had a high lead concentration, while the other two segments had a low concentration. These findings indicate an episodic intake of lead of various amounts that may be immediately fatal (generating high blood levels) or sublethal. The patterns of lead in flight feathers and in bone suggest a repeated sublethal lead intake by the same individual. Such an episodic lead uptake seems only possible through ingestion of lead particles from carcasses or offal left behind by hunters. This also constitutes a risk to other scavengers, notably to the bearded vulture Gypaetus barbatus for which several high bone lead values have been found.

Differential range use between age classes of southern African Bearded Vultures Gypaetus barbatus.

Bearded Vulture Gypaetus barbatus movements were investigated in southern Africa to determine whether an individual's age, sex or breeding status influenced its ranging behaviour and to provide the information required to guide conservation activities. Data from satellite transmitters fitted to 18 individuals of four age classes were used to determine range size and use. Because of the nature of the movements of marked individuals, these data could be used to determine the overall foraging range of the entire population, which was estimated to be 51 767 km2. Although juvenile, immature and sub-adult birds used different parts of the overall range, their combined foraging range was 65% (33 636 km2) of the overall range. Average adult home ranges (286 km2) were only around 1% the size of the average foraging ranges of non-adults (10 540 –25 985 km2), with those of breeding adults being even smaller (95 km2). Home ranges of breeding adults did not vary in size between seasons but adults utilized their home range more intensively whilst breeding, moving greater distances during the incubation and chick hatching period. Range size and use increased as non-adults aged. Immatures and sub-adults had larger range sizes during winter, but range use of non-adults did not vary seasonally. Range size and use did not differ between the sexes in any of the age classes. Information on home range size and use enables specific areas within the species' range to be targeted for management planning, education and conservation action.

Home Ranges and Movements of Non-Breeding Bearded Vultures Tracked by Satellite Telemetry in the Pyrenees

We present data on home range sizes and spatial parameters of six non-breeding bearded vultures Gypaetus barbatus (one adult, four subadults and one juvenile) using Argos satellite telemetry in the Pyrenees (Spain-France) between 1999 and 2006. None of the birds left the Pyrenees during the tracking period and all individuals included supplementary feeding stations (SFS) in their home ranges. Home range areas reported here were smaller than those previously reported in South Africa and slightly larger than those reported in the Pyrenees and the Alps. Overlap between home ranges and SFS shows the importance of predictable sources of food, especially for inexperienced juvenile birds. Satellite telemetry facilitates improved insight into the bearded vulture's spatial ecology and behaviour, which is key for the conservation of this threatened species.

Manipulating size, amount and appearance of food inputs to optimize supplementary feeding programs for European vultures

Supplementary feeding is one of the most common techniques used to alleviate threats to scavengers species related to the quality and availability of food resources. Because supplementary feeding may have undesired effects, the management of supplementary sites should be optimized from an ecological and conservation perspective. We installed high-resolution videocameras at six Spanish feeding stations recording more that 7500h of observations at 105 feeding events. We analyzed food preferences in the four European vulture species (Eurasian griffon vulture Gyps fulvus, Egyptian vulture Neophron percnopterus, bearded vulture Gypaetus barbatus and cinereous vulture Aegypius monachus) as they relate to the characteristics of the food remains and carcasses provided at feeding sites. Our results suggest that carrion features (format, scattering, prey species, biomass and items) influence differential selection between species and age-classes. At a species level, large inputs of unscattered carrion increased the abundance of actively feeding griffon vultures. The ratio of the abundance of bearded vultures, Egyptian vultures and cinereous vultures with respect to griffon vultures was favored when less biomass was supplied and when the food provided was not presented as whole carcasses. Thus, using medium-size ungulates (i.e. sheep and goats) presented as small, abundant and scattered pieces favors the consumption of the resource by the most endangered species. Our findings can be used to optimize the supplementary provisioning of vultures in cases where this conservation tool is considered essential for managing targeted species or population groups.

Reduced genetic diversity in Bearded Vultures Gypaetus barbatus in Southern Africa

The Bearded Vulture Gypaetus barbatus occurs throughout its range in small and dwindling population fragments with limited genetic differentiation between populations, suggesting that the species might be managed as a single entity. The numbers of East and Southern African Bearded Vultures included in previous studies were small, so we determine the genetic variation within, evolutionary placement of and connectivity among sub‐Saharan African populations. Mitochondrial DNA fragment analyses detected little or no differentiation between populations in Ethiopia and Southern Africa, with reduced haplotype diversity in Southern Africa compared with populations in the Northern Hemisphere. The results inform conservation management of this species globally and locally, and offer guidelines for translocations should populations continue to decline.

Using manipulation of density‐dependent fecundity to recover an endangered species: the bearded vulture Gypaetus barbatus as an example

Summary Endangered species subjected to reintroduction programmes often occur as small and isolated populations with local high density and depressed fecundity. Variation in territory quality may lead to this low fecundity owing to increasing occupation of suboptimal territories as population density grows, known as the habitat heterogeneity hypothesis (HHH). In this context, food supplementation in poor territories may be used to produce extra young which could be allocated to reintroduction programmes. We analyse the density‐dependent fecundity pattern and the underlying mechanism in a small population of bearded vultures Gypaetus barbatus in Aragón (northeast Spain). We then use population simulations to examine the viability of a hypothetical reintroduction programme using extra young produced by supplementary feeding on poor‐quality territories and the effect on the donor population. We also compare the economic cost of such a reintroduction programme in relation to the cost of a traditional captive breeding programme. The wild population showed clear negative, density‐dependent fecundity regulation driven by the HHH mechanism. Simulations showed that extractions for translocations had no relevant long‐term effects on the donor population viability, but a marked population reduction during the extraction period. However, the implementation of supplementary feeding to produce extra young for translocation lessened significantly this expected initial population reduction. Analyses showed that the annual budget of a captive breeding programme for this species could be seven times more expensive than the translocation of extra young produced by food supplementation. Synthesis and applications. Reintroduction programmes based on translocation of wild‐reared individuals, after a supplementary feeding programme oriented to poor‐quality territories, provide a source of young at least seven times cheaper than those from captive breeding programmes. The use of this approach would decrease initial effects on donor population avoiding public criticism. Increasing the number of young released during the first years of the reintroduction decreases total financial cost and increases the final population size in the new area.

Man-induced activities modify demographic parameters in a long-lived species: effects of poisoning and health policies.

Recent changes in sanitary policies within the European Union (EU) concerning disposal of carcasses of domestic animals and the increase of non-natural mortality factors, such as illegal poisoning, are threatening European vultures. However, the effects of anthropogenic activities on demographic parameters are poorly studied. Using a long-term study (1994-2011) of the threatened Pyrenean Bearded Vulture Gypaetus barbatus population, we assess the variation in the proportion of breeding pairs, egg-laying dates, clutch size, breeding success, and survival following a sharp reduction in food availability in 2005 due to the application of restrictive sanitary policies decreasing livestock carcass availability. We found a delay in laying dates and a regressive trend in clutch size, breeding success, and survival following policy change. The maintenance of specific supplementary feeding stations for Bearded Vultures probably reduced the negative effects of illegal poisoning and food shortages, which mainly affected subadult survival. A drop in food availability may have produced changes in demographic parameters and an increase in mortality due to an increased exposure to contaminated food. As a result, supplementary feeding as a precautionary measure can be a useful tool to reduce illegal poisoning and declines in demographic parameters until previous food availability scenarios are achieved. This study shows how anthropogenic activities through human health regulations that affect habitat quality can suddenly modify demographic parameters in long-lived species, including those, such as survival, with high sensitivity to population growth rate.

Wind farms threaten southern Africa's cliff-nesting vultures

Wind farms have been shown to cause bird mortality in many studies. Proposals for the development of wind farms in Lesotho, which is core habitat for small and declining populations of the regionally Endangered Bearded Vulture Gypaetus barbatus meridionalis and regionally and globally Vulnerable southern African endemic Cape Vulture Gyps coprotheres is therefore of concern. We use satellite tracking data to demonstrate that southern African Bearded Vultures spend the majority of their time foraging in landscape zones typically chosen for wind farm development (active selection for ridge tops and upper slopes), and that both species generally fly at heights within the rotor-sweep of a typical, modern wind turbine. We constructed a population viability model using actual population data from the area presently being targeted by the wind energy industry, calibrated with actual data on local population trends, to assess the potential impact of two specific wind farm development proposals on the populations of both vulture species. Even under conservative assumptions, relatively small-scale wind farm development in the Lesotho Highlands is likely to result in accelerated population decline and extinction in both species. The only feasible mitigation is to move the development sites off the ridge tops and upper slopes.

Philopatry, natal dispersal, first settlement and age of first breeding of bearded vultures Gypaetus barbatus in central Pyrenees

Capsule Male bearded vultures tended to disperse closer to natal territories than females with a preferred eastward natal dispersal direction. In general, birds settled for the first time in breeding territories at an average age of 7.6 years, first breeding attempt occurred at 10.0 years and first successful breeding at 10.4 years. Measures aimed at favouring the settlement of new pairs in the edge of their current distribution area would allow natural range expansion of this endangered species.