Bearded Vulture Gypaetus Barbatus Research Articles

Heterospecific visual cues and trophic facilitation processes used by a solitary bone‐eating vulture

AbstractWhile the influence of public information sharing on foraging strategies is of growing interest, empirical studies exploring intraguild social information use and facilitation roles between individuals with different trophic specializations remain scarce. Heterospecific facilitation should be more common in specialist foragers, for example, the bearded vulture Gypaetus barbatus, a solitary bone‐eating scavenger. We monitored 133 carcasses of different types/sizes in open and shrubland landscapes in the Spanish Pyrenees to explore bearded vulture foraging in relation to social information transfer and adaptive trophic behavior. We hypothesized that they might (1) feed on carcasses after initial heterospecific exploitation; (2) use heterospecifics to locate and/or exploit carcasses; and (3) prefer old carcasses over fresh ones. We recorded bearded vultures scavenging at 44 carcasses; 95.5% had been previously exploited by heterospecifics (93.2% by griffon vultures Gyps fulvus and 2.3% by golden eagles Aquila chrysaetos) while only two small‐sized carcasses were scavenged without previous heterospecific exploitation. Bearded vultures were not observed scavenging at carcasses used only by mammals. Both griffon and bearded vultures took longer to find carcasses in shrublands than in open landscapes. However, bearded vulture arrival times between landscapes after carcass discovery by griffon vultures were similar. Bearded vultures were more likely to discover a carcass the greater the number of griffon vultures exploiting it. Only 10.4% bearded vulture scavenging events occurred after the third week following heterospecific exploitation, suggesting that recently opened carcasses were preferred. Clearly, heterospecifics play an essential role in bearded vultures foraging success, and griffon vultures are fundamental facilitators for specialist foragers, both in providing visual cues to food location and in opening up carcasses to enable access to food.

Demographic assessment of reintroduced bearded vultures in the Alps: Success in the core, challenges in the periphery

Abstract Regular assessment of reintroduced populations is essential to guide management and provide lessons for other reintroduction projects. Bearded vulture Gypaetus barbatus reintroduction in the Alps began in 1986 with the release of the first fledglings, the first successful reproduction was recorded in 1997, and the population has grown steadily since. A previous assessment suggested that no further releases would be required to establish a self‐sustaining population from a demographic point of view. However, this conclusion was based on a small sample size and spatially homogeneous demographic rates of released individuals, which may differ from and be spatially variable among wild‐hatched individuals. Using longitudinal data and breeding site survey data, we constructed an integrated population model to examine the demography of the entire Alpine population, spatially stratified into a core and a periphery. We performed retrospective population analyses to identify demographic reasons for spatial differences in population growth and conducted population viability analyses to assess the impact of future threats and reintroduction options. In 2021, an estimated 172 (CRI: 147–198) females were present in the Alps, of which 65 (CRI: 63–67) were breeders. Adult survival and productivity were higher in the core than in the periphery, so the population grew more strongly in the core than in the periphery. Differences in adult survival contributed most to the differences in population growth between the two areas. The population viability analysis predicts that the Alpine population will double in 10 years but that an increase in the mortality hazard above 0.055 will lead to a population decline. Unlike the population in the core, the population in the periphery is dependent on further releases at this stage. Bearded vulture reintroductions in the Alps have succeeded in creating a self‐sustaining population with higher reproductive success and similar survival probabilities to the autochthonous Pyrenean population. In general, management should focus on preventing further mortality risks. In the periphery, reducing current mortality and increasing reproductive success are essential to make the population independent of releases.

Survival Estimation Using Multistate Cormack–Jolly–Seber Models—The Case of the Bearded Vulture Gypaetus barbatus in Spain

The bearded vulture (Gypaetus barbatus) is an endangered species with a specialist osteophagous (bone) diet. We estimated the survival and productivity of this vulture in the Aragonese Pyrenees, where the main population of the species in Europe is found. We used a database covering a period of 33 years (1987–2020). To estimate the probability of survival, we used Cormack–Jolly–Seber models with a Bayesian approach. Our models estimated a survival rate of 0.90 ± 0.08 in juveniles, 0.95 ± 0.04 in subadults and 0.92 ± 0.05 in adults. The survival probability increased over the study period in adults and subadults but not in juveniles. By contrast, productivity decreased over the same period. Our study provides updated information on the status of two demographic parameters of great importance to the species and allows us to identify the most vulnerable age classes and to plan conservation actions to improve the situation of the species in a territory that is a donor of specimens for reintroduction projects. The estimated survival values suggest that more caution should be exercised when planning these feeding points according to the use the species makes of them.

Global range dynamics of the Bearded Vulture (Gypaetus barbatus) from the Last Glacial Maximum to climate change scenarios

Species' ranges are dynamic, particularly at large temporal scales. The reconstruction of range dynamics has an obvious biogeographical interest and might also help to frame current knowledge on the ecology and conservation of a species within a wider biogeographical context. The Bearded Vulture Gypaetus barbatus is a charismatic high‐altitude species occurring along mountain ranges of the Old World. The species has experienced a global range contraction in the last century mainly due to unintentional poisoning and direct persecution. Despite its declining status and high habitat specialization, little is known about how climate change is impacting the distribution of suitable habitat, or about global past range dynamics of the species. We modelled the current distribution of Bearded Vulture throughout its entire range and projected the Last Glacial Maxima (LGM), Mid‐Holocene (MH) and future distribution under 2070s climate change scenarios. Overall, our models predicted that expansion of suitable areas at more northern latitudes for 2070, mostly in Russia and China, does not compensate for range contraction at more southern latitudes, resulting in a global loss of 15% of suitable habitat. Our fine‐scale predictions of habitat contraction due to climate change will assist in identifying current portions of the range that might be particularly vulnerable in coming years. African populations (34% decrease) and more thermic areas in Asia are the most impacted areas, and should be at the forefront of future monitoring and conservation efforts. Our models suggest that the predicted contraction in habitat suitability during the 21st century largely continues the contraction experienced since the LGM (7% decline), albeit over a much shorter period of time. From a biogeographical perspective, our models suggest that there have not been relevant changes in the arrangement of the main suitable areas for the species since the LGM. This result challenges some of the main hypotheses proposed to explain the observed genetic structure of the global population.

Новая встреча бородача на западном чинке плато Устюрт в Казахстане в 2022 году

The article highlights data on the first sighting of bearded vulture Gypaetus barbatus on the territory of the Ustyurt State Nature Reserve (Kazakhstan) after 2013. It has been suggested that the bearded vulture is periodically visiting from the Great Balkan Range (Western Turkmenistan) and the subspecies of the bird encountered.

Adult coloration of the Bearded Vulture (Gypaetus barbatus) in the Pyrenees: relation to sex, mating system and productivity

Cosmetic coloration is not a common phenomenon among bird species. Adult Bearded Vultures Gypaetus barbatus typically show orange coloration in head, chest, belly and tarsus feathers that is the result of mud baths in ferruginous substrates. Several non‐mutually exclusive visual signalling hypotheses can be proposed to explain this phenomenon. Coloration could be used to signal: (1) dominance towards conspecifics, with darker birds being dominant (status signalling hypothesis); (2) sex (gender signalling hypothesis) because females are usually more intensely coloured; (3) individual quality for mate choice (quality signalling hypothesis); or (4) different reproductive strategies between individuals (e.g. in polyandrous trios). Here we report results from systematic monitoring of breeding Bearded Vultures in the pre‐laying period in the central and western Pyrenees (Spain and France) between 2016 and 2020, including 162 individuals from 70 reproductive units (48 pairs and 22 trios). We classified individuals as being white, pale, medium or dark, and analysed the relationship with sex, mating system (pair or trios) and average productivity across years. Our results showed that the most common form was medium (67%), then pale (22%), dark (9%) and white (2%) morphs. Overall, females were darker than males, but with a large overlap in coloration. In trios, dominant males were darker than subordinate males, although differences were not statistically significant. The mating system (pair or trio) did not influence female coloration. A multimodel comparison showed that the number of years of territory occupation, mating system and their combination (but not coloration) were the best predictors of average productivity. Our results do not support the gender signalling hypothesis. The reproductive strategy signalling hypothesis might be supported because beta males were, on average, paler than males in pairs, but this topic requires further investigations because our results were inconclusive. Finally, that females (thought to be dominant because of their slightly larger size) were on average darker than males agrees with the status signalling hypothesis, although an experimental approach would be needed to formally test this hypothesis.

Cosmetic plumage coloration by iron oxides does not confer protection against feather wear

The active acquisition of plumage cosmetic coloration by iron oxides has been described in several bird species (notably the Bearded Vulture Gypaetus barbatus, but also in cranes, pelicans and other vulture species) but its function remains controversial. We tested the hypothesis that iron oxide acquired through mud bathing protects feathers from wear. We experimentally stained 13 breast feathers collected from two White Storks Ciconia ciconia with mud from a ferruginous pond regularly used by Bearded Vultures, while another 13 feathers (controls) were treated with water. All feathers were exposed to a controlled physical abrasion treatment. We found no differences in wear between control and stained feathers, which is counter to predictions of the wear protection hypothesis for the acquisition of this cosmetic plumage coloration.

Influence of individual biological traits on GPS fix-loss errors in wild bird tracking

In recent decades, global positioning system (GPS) location data and satellite telemetry systems for data transmission have become fundamental in the study of basic ecological traits in wildlife biology. Evaluating GPS location errors is essential in assessing detailed information about the behaviour of an animal species such as migration, habitat selection, species distribution or foraging strategy. While many studies of the influence of environmental and technical factors on the fix errors of solar-powered GPS transmitters have been published, few studies have focussed on the performance of GPS systems in relation to a species’ biological traits. Here, we evaluate the possible effects of the biological traits of a large raptor on the frequency of lost fixes—the fix-loss rate (FLR). We analysed 95,686 records obtained from 20 Bearded Vultures Gypaetus barbatus tracked with 17 solar-powered satellite transmitters in the Pyrenees (Spain, France and Andorra), between 2006 and 2019 to evaluate the influence of biological, technical, and environmental factors on the fix-loss rate of transmitters. We show that combined effects of technical factors and the biological traits of birds explained 23% of the deviance observed. As expected, the transmitter usage time significantly increased errors in the fix-loss rate, although the flight activity of birds revealed an unexpected trade-off: the greater the proportion of fixes recorded from perched birds, the lower the FLR. This finding seems related with the fact that territorial and breeding birds spend significantly more time flying than non-territorial individuals. The fix success rate is apparently due to the interactions between a complex of factors. Non-territorial adults and subadults, males, and breeding individuals showed a significantly lower FLR than juveniles-immatures females, territorial birds or non-breeding individuals. Animal telemetry tracking studies should include error analyses before reaching any ecological conclusions or hypotheses about spatial distribution.

An Assessment of Population Size and Demographic Drivers of the Bearded Vulture Using Integrated Population Models

Conventional approaches for the assessment of population abundance or trends are usually based on a single source of information, such as counts or changes in demographic parameters. However, these approaches usually neglect some of the information needed to properly understand the population as a whole, such as assessments of the non-breeding proportion of the population and the drivers of population change. The Bearded Vulture Gypaetus barbatus is a threatened species and its Pyrenean population (the largest in Europe) inhabits parts of Spain, Andorra, and France. We developed an Integrated Population Model (IPM) using data from a long-term study (1987–2016) in the three countries, including capture–mark–recapture of 150 marked individuals, to assess population size and age structure at the whole population scale, and obtain estimates of survival and breeding parameters of this population. The breeding population experienced a geometric mean population increase of 3.3% annually, falling to 2.3% during the last 10 yr. The adult proportion of the population increased with time, from 61% to 73%. There were 365 (95% Bayesian credible interval [BCI]: 354–373) adult breeding birds in 2016, representing 49% of the adult population and 36% of the total population (estimated at 1,026 individuals, 95% BCI: 937–1,119). The large number of non-breeding adults probably led to higher mean age of first reproduction than previously estimated, and to an estimated 30–35% of territories occupied by polyandrous trios. Population growth rate was positively and strongly correlated with adult survival, which had a much greater effect on population growth than productivity. The effects of subadult and juvenile survival on population growth were weaker. We found strong evidence for a density-dependent decrease in juvenile survival, productivity and adult survival, leading to reduced population growth with increased population size. Our approach allowed us to identify important conservation issues related to the management of supplementary feeding sites and geographic expansion of this population. Our study supports the use of IPMs as a tool to understand long-lived species, allowing simultaneous estimates of the non-breeding size of the population (which is critical for understanding population functioning), better estimates of population parameters, and assessment of demographic drivers.

Breeding site records of three sympatric vultures in a mountainous cliff in Kahara-Thathri, Jammu & Kashmir, India

The current communication deals with the breeding records of three sympatric vultures, viz., Himalayan Vulture Gyps himalayensis, Egyptian Vulture Neophron percnopterus, and Bearded vulture Gypaetus barbatus from a mountain cliff in Kahara, Thathri, a part of upper Chenab catchment in the union territory of Jammu and Kashmir. Made of twigs and lined by dry grass, the nests mostly east-facing, were built on the ledges or in cavities and small caves on cliffs well protected from predators. The inaccessibility, rugged topography (for nesting) and the abundant food base (gorals, monkeys, langurs, pikas, and rodents) make it an ideal nesting location for the vultures. Authors suggested that intensive studies are required to be taken up on the resource apportionment and influence of habitat variables (climate, terrain, disturbance) on the nest site characteristics in such rugged landscapes.

An assessment of population size and demographic drivers of the Bearded Vulture using integrated population models

AbstractConventional approaches for the assessment of population abundance or trends are usually based on a single source of information, such as counts or changes in demographic parameters. However, these approaches usually neglect some of the information needed to properly understand the population as a whole, such as assessments of the non‐breeding proportion of the population and the drivers of population change. The Bearded Vulture Gypaetus barbatus is a threatened species and its Pyrenean population (the largest in Europe) inhabits parts of Spain, Andorra, and France. We developed an Integrated Population Model (IPM) using data from a long‐term study (1987–2016) in the three countries, including capture–mark–recapture of 150 marked individuals, to assess population size and age structure at the whole population scale, and obtain estimates of survival and breeding parameters of this population. The breeding population experienced a geometric mean population increase of 3.3% annually, falling to 2.3% during the last 10 yr. The adult proportion of the population increased with time, from 61% to 73%. There were 365 (95% Bayesian credible interval [BCI]: 354–373) adult breeding birds in 2016, representing 49% of the adult population and 36% of the total population (estimated at 1,026 individuals, 95% BCI: 937–1,119). The large number of non‐breeding adults probably led to higher mean age of first reproduction than previously estimated, and to an estimated 30–35% of territories occupied by polyandrous trios. Population growth rate was positively and strongly correlated with adult survival, which had a much greater effect on population growth than productivity. The effects of subadult and juvenile survival on population growth were weaker. We found strong evidence for a density‐dependent decrease in juvenile survival, productivity and adult survival, leading to reduced population growth with increased population size. Our approach allowed us to identify important conservation issues related to the management of supplementary feeding sites and geographic expansion of this population. Our study supports the use of IPMs as a tool to understand long‐lived species, allowing simultaneous estimates of the non‐breeding size of the population (which is critical for understanding population functioning), better estimates of population parameters, and assessment of demographic drivers.

Potential release sites and strategies for a Bearded Vulture Gypaetus barbatus reintroduction in South Africa

The southern African population of Bearded Vultures Gypaetus barbatus has declined rapidly and it is threatened with extinction. In response to this decline and the additional threats of wind farm developments in the core of the species’ range, it has been proposed to establish a reintroduced population within their historic South African range as insurance against regional extinction. To facilitate such a reintroduction, we used Maximum Entropy Modelling based on suitable nesting habitat to identify and define five potential reintroduction sites. We then compared the suitability of these sites based on the quantification of various threats and benefits within each site. The two highest-ranking sites were located mostly in the Eastern Cape Province of South Africa. We then compared different release strategies, using a Population Viability Analysis, to determine which approach would be most likely to be successful (defined as >34 individuals after 30 years). These models suggest that establishing a captive breeding programme and releasing captive-bred young would lower failure rates to 25.5–49.8%, compared with the direct releases of wild taken fledglings, without a supporting captive breeding programme (78.3–95.7%). Our models also suggest that even in the presence of high mortality rates at the reintroduction site, such a reintroduction would still be a worthwhile project, because it reduces the probability of extinction of the southern African population by approximately 30% over a 50-year period.

Nocturnal flights by Bearded Vultures Gypaetus barbatus detected for the first-time using GPS and accelerometer data

ABSTRACT Capsule: We document previously undescribed nocturnal flight behaviour by Bearded Vultures Gypaetus barbatus using a combination of accelerometer and global positioning system (GPS) information. Aims: To study the nocturnal flight activity of the Bearded Vulture and determine whether nocturnal flights could be linked to foraging behaviour. Methods: We used both accelerometer and GPS location data of 11 Bearded Vultures in the Spanish Pyrenees along with 88 carcasses monitored with camera traps. Results: Over half (55%, n = 11) of the individuals tracked were recorded flying between 0.7 and 6.1 km on at least 19 different nights, including 37% that occurred when less than 20% of the moon was illuminated. Bearded Vultures displayed feeding activity in only 8.2% of the 146 feeding events existing during the hour after dawn and the hour before dusk. Conclusions: Our findings suggest that foraging benefits do not explain the nocturnal flights. Disturbances or adverse weather conditions may result in the abandonment of an overnight roosting site. This could also explain why individuals recovered in the field showed impact injuries.

Spatial and temporal movement of the Bearded Vulture using GPS telemetry in the Himalayas of Nepal

This study addresses for the first time the movement patterns of the globally near‐threatened Bearded Vulture Gypaetus barbatus in its most important stronghold, the high‐altitude mountain ranges of Asia. Tracked individuals (n = 8) in the Annapurna Himalayan range (Nepal) foraged over a vast range of 60 715.9 km2 and our results indicated age‐class differences in the use of space. Territorial adults showed very small annual home‐ranges (K90 = 150.3 km2), whereas immatures wandered extensively and covered vast ranges of the mountains (K90 = 23 930.8 km2). For adults and immatures, these values are notably larger than the other two studied populations in the world (Pyrenees and South Africa). This suggests that the studied Annapurna population might exhibit lower breeding density than in the Pyrenees or South Africa, possibly due to lower food availability.

Potential exposure to diclofenac in Spain of European vultures

Diclofenac (NSAID) for veterinary use, the same that previously reduced south Asian Gyps vulture populations by nearly 99% in the late 1990s, was approved in Spain in 2013 for cattle, swine and horses. We assessed its availability and the potential exposure to European Griffon Gyps fulvus, Cinereous Aegypius monachus, Egyptian Neophron percnopterus and Bearded vultures Gypaetus barbatus in Spain. In 2014, a telephone questionnaire to 1073 official pharmaceutical distributers (POS) found 230 responses and 82 were currently selling diclofenac. The preliminary assessment for Spain showed a widespread exposure to diclofenac that extends across 275,391 km2, i.e. 54% of the territory. Diclofenac availability is related to livestock densities and certain rearing practices, especially cattle and extensive swine farming, but not with horse farms. Livestock farming carcass disposal practices and subsequent carcass availability to vultures are of concern when controlling for diclofenac potential use and residues in corpses. Overlap of diclofenac exposure with vulture distribution ranges and population sizes per region were highest for Cinereous Vulture (88% and 73% overlap with range and population size respectively), 62/56% for the Egyptian Vulture, 58/57% for the Griffon and 42/36% for the Bearded Vultures. Ensuring the safety of carcasses consumed by vultures with specific tests for NSAIDs and their use in farming practices is required.

Home range and habitat use of a bearded vulture Gypaetus barbatus L., 1758 along the western border of its Pyrenean distribution area

espanolGipuzkoa es una region que cuenta con una presencia constante de quebrantahuesosGypaetus barbatusL., 1758, pero el proceso de colonizacion es lento, posiblemente debidoa la dificultad de que se consoliden parejas estables. Este articulo pretende contribuir aevaluar el rol de Gipuzkoa, que se situa en el borde occidental del area de distribucion dela poblacion pirenaica de quebrantahuesos, en la expansion de la especie y su conservacion.Para ello se utilizaron los datos que fueron proporcionados por un ave adulta que fueequipado con un GPS. Las localizaciones de este ejemplar dieron un area de campeo de235 km2, coincidente en su mayor parte con las montanas de Aralar, si bien este ejemplartambien realizo algunas “excursiones” al sector centro-occidental de los Pirineos, proba-blemente en busca de interacciones sociales. Nuestros resultados sugieren que Gipuzkoaofrece buenas condiciones ambientales para la especie, si bien el ambiente social es defi-ciente. En consecuencia, y en comparacion con otras zonas del Pirineo, la colonizacion deGipuzkoa y otras zonas marginales al area de distribucion de la especie en el Pirineo eslenta, posiblemente debido a la gran proporcion de aves transeuntes y la dificultada deque se asienten aves maduras experimentadas capaces de establecer parejas solidas y per-manentes. EnglishThe region of Gipuzkoa is used on a permanent basis by the bearded vulture GypaetusbarbatusL., 1758, but the colonization process is slow, apparently due to the difficulty offinding a permanent mate. This article aims to contribute to evaluating the role of Gipuz-koa, which forms the western border of the Pyrenean population of bearded vulture, inthe expansion and conservation of the species. We used data from a territorial adult malewhich was captured and GPS-tracked. GPS data revealed a habitual home range area of235 km2within the Aralar mountains and its surroundings, although this bird also made“excursions” to the western-central Pyrenees, probably in search of social interactions.Our results thus suggest that Gipuzkoa presents a good foraging environment althoughthis is offset by a poor, deficient, social environment. Consequently, compared to zones inthe eastern Pyrenees, the colonization of Gipuzkoa and other regions along the west of the Pyrenees is slow, due seemingly to the very high proportion of transients and the difficulties that settled individuals experience in finding a permanent mate. euskaraGipuzkoako eremuan Gypaetus barbatusL., 1758 ugatzen populazio egonkorra bizi da,baina kolonizazio prozesua motel doa, agian bikote iraunkorrak egonkortzeko zailtasuna-gatik. Gipuzkoa Pirinioetako ugatzen populazioaren banaketari dagokionez mendebaldekoertzean kokatzen delarik, artikulu honek herrialdeak zer rol duen ebaluatzen lagundu nahiluke, espeziearen zabalkundean eta iraupenean. Xede horretarako ale heldu batek eskaini-tako datuak baliatu dira, zeinari GPS bat atxiki zitzaion. Hegazti horren lokalizazioenemaitza 235 235 km2-ko eremu bat izan zen, gehiena zuzenki lotuta Aralarrekomendiekin, nahiz eta hegaztiak “ateraldi” batzuk ere egin zituen Pirinioetako erdi-mende-balderantz, ziurrenik kideekin interakzio bila. Gure emaitzek iradokitzen dutenez,Gipuzkoak ingurune baldintza onak ditu espeziearentzat, baina ingurune soziala eskasada. Ondorioz, eta Pirinioetako beste eremu batzuekin alderatuta, Gipuzkoako kolonizazioaedota espeziearen banaketako beste bazter eremu batzuetakoa geldoa da, agian pasekohegazti proportzio handiagatik eta hegazti helduak bertan kokatzeko zailtasunagatik, aleeskarmentukoak, bikote egonkorrak eta iraunkorrak sortzeko gai direnak

Bioinspired models for assessing the importance of transhumance and transboundary management in the conservation of European avian scavengers

The assessment of temporal and spatial availability of food resources is an important prerequisite in developing improved management tools for effective conservation action. It is especially useful in the conservation of avian scavengers inhabiting regions where livestock move on a regular basis (transhumance). Important management decisions can be taken on the basis of theoretical analyses that need to be regularly checked. In this case study, we consider models of Griffon vulture Gyps fulvus, Egyptian vulture Neophron percnopterus and bearded vulture Gypaetus barbatus populations in a part of Spain with one of the highest densities of scavenging birds, and where traditional farming practices remain. We applied bioinspired Population Dynamic P System models (PDP) to assess these species' population trends against the distribution, quantity and availability of carrion for food. We show asymmetries in the availability of food resources, which are substantially higher in summer due to transhumant movements. In the study area, a lack of food resources in winter leads to a seasonal reduction in food supplies to levels unable to meet the energetic requirements of the most abundant vulture species, the Griffon vulture. Our results suggest that regardless of active management (e.g. supplementary feeding sites) and the birds’ use of other potential food resources not included in the model, Griffon vultures are able to find important alternative food resources in more remote areas. We show the importance of variations at spatio-temporal scales in the objective forecasting of population trends, and in the correct application of management actions. Because of the importance of robust assessments for management applications, we discuss the advantages and limitations of ecological modelling for avian scavengers, highlighting the importance of transhumance processes and transboundary approaches.

Drivers of daily movement patterns affecting an endangered vulture flight activity

BackgroundThe development of satellite tracking technology enables the gathering of huge amounts of accurate data on animal movements over measured time intervals, to reveal essential information about species’ patterns of spatial use. This information is especially important in optimizing the design of conservation and management strategies for endangered species. In this study, we analysed the main drivers of daily patterns in the flight activity of the threatened Bearded Vulture Gypaetus barbatus. We studied 19 Bearded Vultures tagged with solar-powered GPS transmitters from 2006 to 2016 in the Pyrenees (Spain). We assessed the relative influence of external factors (season and daylight time) and internal factors (sex, breeding season and territorial status) on their daily activity behaviour by computing mean hourly distance travelled, maximum displacement and cumulative distance travelled per hour.ResultsOur findings showed a clear difference in all the estimators between territorial and non-territorial (floating) members of the population, showing that non-territorial individuals spent much longer in flight and travelled larger distances per day. We detected an important influence of daylight time and season on the daily rhythms of Bearded Vultures; flight activity increased during the last three quarters of daylight and was greatest in the spring. Breeding period and sex had also an effect on the maximum displacement and cumulative distance travelled. Individuals flew more during the breeding period and females tended to exhibit greater cumulative and maximum distances per hour than males regardless of breeding season.ConclusionsPyrenean Bearded Vultures flight daily activity was strongly influenced by daylight time, season, and territorial status, while individual sex and breeding season showed a milder effect on the birds’ movement behaviour. This study gives a novel insight into how external factors act as main drivers of the daily flight activity pattern of a long-lived avian scavenger.

Acute and Chronic Lead Exposure in Four Avian Scavenger Species in Switzerland.

Despite irrefutable evidence of its negative impact on animal behaviour and physiology, lethal and sublethal lead poisoning of wildlife is still persistent and widespread. For scavenging birds, ingestion of ammunition, or fragments thereof, is the major exposure route. In this study, we examined the occurrence of lead in four avian scavengers of Switzerland and how it differs between species, regions, and age of the bird. We measured lead concentration in liver and bone of the two main alpine avian scavengers (golden eagle Aquila chrysaetos and bearded vulture Gypaetus barbatus) over the entire area of the Swiss Alps and two of the main avian scavengers occurring in the lowlands of Switzerland (red kite Milvus milvus and common raven Corvus corax). Of those four species, only the bearded vulture is an obligate scavenger. We found that lead burdens in the two alpine avian scavengers were higher than those found for the same species elsewhere in Europe or North America and reached levels compatible with acute poisoning, whereas lead burdens of the two lowland avian scavengers seemed to be lower. Several golden eagles, but only one red kite with abnormally high bone lead concentrations were found. In all four species, a substantial proportion of birds had elevated levels which presumably represent recent (liver lead levels) or past (bone lead levels) uptake of sublethal doses of lead.

Philopatry in a reintroduced population of Bearded Vultures Gypaetus barbatus in the Alps

Following its eradication in the Alps in the early 1900s, the Bearded Vulture Gypaetus barbatus has been reintroduced in four Alpine regions since 1986. The first successful breeding since this reintroduction into the wild occurred in 1997 in the western Alps, and in 1998 in the Central Alps, thereby establishing two subpopulations. Here, we focus on the growth and the settlement patterns of one of the major subpopulations of reintroduced Bearded Vulture, that of the Central Alps. By 2015 there were 15 breeding pairs in the Central Alps, and the density within the core area was strikingly higher (18.8 pairs/1000 km2) than that outside it (overall density 3.4 pairs/1000 km2). New pairs showed high natal philopatry when settling, with maximum distances of 49.2 km from the nearest release sites. Among identified birds, born or released within the Central Alps, 85% (n = 26) paired and settled within this subpopulation and only four birds emigrated to the west. Three birds immigrated from the east or the west. Both the number of pairs and of offspring increased exponentially between 1998 and 2015. The growth of the Central Alpine subpopulation was characterized by concentric and continuous growth around the release sites. Moreover, there was an increase in the density of pairs within the core area. Possible explanations for the high natal philopatry observed include adaptive genetic components, abundant food resources and conspecific attraction. As a consequence of the substantial population increase, releases in the Central Alpine subpopulation were stopped after 2008. The population has grown almost exclusively on the basis of wild-born birds since then, and has become a major subpopulation of the Bearded Vulture in the Alps.