White-backed Vulture Gyps Africanus Research Articles

Application of GPS occurrence data to understand African white-backed vultures Gyps africanus spatial home range overlaps.

Understanding key overlap zones and habitats which are intensively shared by species in space and time is crucial as it provides vital information to inform spatial conservation with maximum benefits. The advent of high‐resolution GPS technologies associated with new analytical algorithms is revolutionizing studies underpinning species spatial and social interaction patterns within ecosystems. Here, using a robust home range estimation algorithm, the autocorrelated kernel density estimator (AKDE) equipped with an equally powerful home range overlap metric, the Bhattacharyya's coefficient (BC), we provide one of the first attempts to estimate and delineate spatial home range overlap zones for critically endangered African white‐backed vultures to inform conservation planning. Six vultures were captured in Hwange National Park using a modified cannon net system after which they were tagged and tracked with high‐resolution GPS backpacks. Overall, results suggested weaker average home range overlaps based on both the pooled data (0.38 ± 0.26), wet non‐breeding seasonal data (0.32 ± 0.23), and dry breeding season data (0.34 ± 0.28). Vultures 4, 5, and 6 consistently revealed higher home range overlaps across all the scales with values ranging between 0.60 and 0.99. Individual vultures showed consistence in space use patterns as suggested by high between‐season home range overlaps, an indication that they may be largely resident within the Hwange ecosystem. Importantly, we also demonstrate that home range overlapping geographic zones are all concentrated within the protected area of Hwange National Park. Our study provides some of the first results on African vulture home range overlaps and segregation patterns in the savanna ecosystem based on unbiased telemetry data and rigorous analytical algorithms. Such knowledge may provide vital insights for prioritizing conservation efforts of key geographic overlap zones to derive maximum conservation benefits especially when targeting wide‐ranging and critically endangered African white‐backed vultures. To this end, spatial overlap zones estimated here, although based on a small sample size, could provide a strong foundation upon which other downstream social and ecological questions can be explored further to expand our understanding on shared space use mechanisms among African vulture species.

Molecular characterization of Gyps africanus (African white-backed vulture) organic anion transporter 1 and 2 expressed in the kidney.

Gyps species have been previously shown to be highly sensitive to the toxic effects of diclofenac, when present in their food sources as drug residues following use as a veterinary medicine. Vultures exposed to diclofenac soon become depressed and die with signs of severe visceral gout and renal damage on necropsy. The molecular mechanism behind toxicity and renal excretion of uric acid is still poorly understood. With the clinical pictures suggesting renal uric acid excretion as the target site for toxicity, as a first step the following study was undertaken to determine the uric acid excretory pathways present in the African white-backed vulture (Gyps africanus) (AWB), one of the species susceptible to toxicity. Using transcriptome analysis, immunohistochemistry and functional predictions, we demonstrated that AWB makes use of the organic anion transporter 2 (OAT2) for their uric acid excretion. RT-qPCR analysis subsequently demonstrated relatively similar expression of the OAT2 transporter in the vulture and chicken. Lastly docking analysis, predicted that the non-steroidal drugs induce their toxicity through an allosteric binding.

Vulture numbers and densities in a large protected savannah in West Africa

A number of vulture species were ubiquitous in undisturbed West African savannahs. However, in recent decades most species have declined rapidly and some are now at the brink of extinction. For some species, large protected areas are their last strongholds, but even there pronounced declines have become obvious in recent years. However, we lack even basic knowledge about current distribution, densities, movement patterns and threats. Comoé National Park (CNP) in northeast Côte d’Ivoire is one of the largest protected savannahs in West Africa and still hosts breeding populations of three critically endangered species (Hooded Vulture Necrosyrtes monachus, White-backed Vulture Gyps africanus, White-headed Vulture Trigonoceps occipitalis). In total, 590 km of searches for vultures and their nests were conducted on foot in southwest CNP in the dry seasons of 2018 and 2019. Thirty-seven active vulture nests (Hooded Vulture – 2, White-backed Vulture – 32, White-headed Vulture – 3) were discovered. CNP may be one of the last refuges for these species in Côte d’Ivoire and important for their conservation in West Africa. There are, however, hints that vultures have declined in CNP since the 1990s and are now rarer especially at the Park's fringe. Together with observations of increasing poaching activities, this underlines that large reserves with strict law-enforcement are needed to save West Africa's vultures from extinction.

Interactions between Pied crows Corvus albus and breeding White-backed vultures Gyps africanus

African White-backed vultures Gyps africanus are Critically Endangered, mainly due to mortality from poisoning, but the species also exhibits variable breeding productivity that may partially be explained by nest failure due to predation. Pied crows Corvus albus have been implicated as nest predators, but because there is no evidence linking Pied crows to low breeding productivity of White-backed vultures, we used a combination of dummy eggs (n = 14) and camera traps on active nests (n = 10), to investigate what species visit White-backed vulture nests (both active and abandoned) and predate on their eggs. We recorded 47 egg predation events, of which 37 (79%) were attributable to Pied crows, while other predators (unidentified large raptors, White-backed vultures and Vervet monkeys) were recorded interacting with eggs 5 times in total; mobbing by Pied crows of incubating vultures increased the probability vultures would abandon their nest but crows did not eat abandoned eggs as soon as they were available. Further studies are needed across a wider range of vulture breeding areas to contextualise these findings both in terms of breeding productivity and the significant risks of mortality faced by vultures from poisoning and other threats.

Association between hunting and elevated blood lead levels in the critically endangered African white-backed vulture Gyps africanus

Lead (Pb) toxicity caused by the ingestion of Pb ammunition fragments in carcasses and offal is a threat to scavenging birds across the globe. African vultures are in critical decline, but research on whether Pb exposure is contributing to declines is lacking. In Africa, recreational hunting represents an important economic activity; however, Pb in leftover hunted carcasses and gut piles represents a dangerous food source for vultures. It is therefore important to establish whether recreational hunting is associated with Pb exposure in African vultures. We explored this issue for the critically endangered white-backed vulture (Gyps africanus) in Botswana by examining their blood Pb levels inside and outside of the hunting season, and inside and outside of private hunting areas. From 566 birds captured and tested, 30.2% birds showed elevated Pb levels (10 to <45 μg/dl) and 2.3% showed subclinical exposure (≥45 μg/dl). Higher blood Pb levels were associated with samples taken inside of the hunting season and from within hunting areas. Additionally, there was a significant interaction between hunting season and areas, with Pb levels declining more steeply between hunting and non-hunting seasons within hunting areas than outside them. Thus, all our results were consistent with the suggestion that elevated Pb levels in this critically endangered African vulture are associated with recreational hunting. Pb is known to be highly toxic to scavenging birds and we recommend that Pb ammunition in Botswana is phased out as soon as possible to help protect this rapidly declining group of birds.

Not in wilderness: African vulture strongholds remain in areas with high human density.

Vultures constitute an important functional group in many ecosystems, providing crucial ecosystem services both in natural and humanized environments. These scavengers are facing massive declines worldwide, but in several African countries virtually nothing is known on populations’ status and threats, hampering the development of adequate conservation strategies. In Guinea-Bissau, globally important populations of Hooded Necrosyrtes monachus and African white-backed vultures Gyps africanus were recently reported. Using the country as a study area, we aim to characterize human-vulture interactions in West Africa applying a multidisciplinary approach. We assessed the status and distribution of vulture populations using data from 1711 km of roadside transects, examined predictors of their distribution, and produced a nationwide population estimate for the Hooded Vulture, using an innovative method based on the relationship between the size of human population in settlements and vulture numbers. We conducted 47 stakeholder interviews to assess perceived roles played by vultures, and to investigate potential anthropogenic threats. Hooded vultures were strongly associated with high human population densities, whereas no relation was found between African white-backed and Rüppell’s vultures and any of the tested predictors, which included cattle density, precipitation and Normalized Difference Vegetation Index, among others. We estimate a national population of 43347 Hooded vultures, the largest population reported in the species range. Respondents were generally aware of the services provided by vultures, especially waste and carcass removal, including in urban areas. Hunting for witchcraft and traditional medicine was the most frequently recognised threat, while poisoning was ranked as having the highest impact. We hypothesise that poisoning-related mortality may be affecting African white-backed and Rüppell’s vultures’ distribution and explain their scarcity in apparently highly suitable habitats. Our results suggest a mutualistic rather than a commensalistic relationship between vultures and humans, with important implications for designing and implementing conservation strategies.

White-backed Vulture Gyps africanus parental care and chick growth rates assessed by camera traps and morphometric measurements

Persistent vulture declines across Africa are a cause for concern as the number of species threatened with extinction increases. The White-backed Vulture Gyps africanus was, until recently, considered abundant but has been declining rapidly in recent years due to various threats including decreasing food availability. We used camera traps to investigate nest attendance and food provision at the nests of White-backed Vultures in north-eastern Swaziland. Chick age influenced brooding behaviour of the parents, with a reduction in brooding time as the chick aged. Mean food provision rate by parents to the nestling was 0.7 bouts d−1, which was mostly delivered between 09:00 and 15:00. Contrary to expectations, provisioning rates did not increase with age of the chick despite both adults delivering food. The growth of chicks showed a curvilinear relationship with age for the first 100 d with the tarsus and bill reaching maximum length after 80 d. We recommend further research into the availability of food for breeding vultures in order to understand the emerging threat of declining food availability in Africa.

Status of birds of prey in Guinea-Bissau: first assessment based on road surveys

Several studies have reported marked declines in populations of birds of prey across the African continent, including West Africa. However, there are still regions of which virtually nothing is known, as is the case for Guinea-Bissau. Because birds of prey play important roles in ecosystems and several species are threatened, it is important to establish baseline knowledge on their status. This is the first study in the country focusing exclusively on birds of prey. We conducted 1 711 km of roadside transects from mid-February to the end of May 2016, covering most of Guinea-Bissau. In total 4 989 birds of 33 species were counted, of which Hooded Vultures Necrosyrtes monachus were the most common (252 birds per 100 km, the second highest abundance in all the species’ range). Observations outside transects, including during regular field trips throughout the country, particularly between 2012 and 2016, were used as complementary information adding 13 species to the list, and contributing three new species for Guinea-Bissau: Ayres’s Hawk-eagle Hieraaetus ayresii, Booted Eagle Hieraaetus pennatus and Lesser Kestrel Falco naumanni. Most species showed differences in abundance in relation to vegetation cover (based on the normalised difference vegetation index). Apart from Hooded Vultures and White-backed Vultures Gyps africanus, all other raptors in the IUCN Red List were found to be scarce, including other vultures and several medium-to-large eagles.

A clear and present danger: impacts of poisoning on a vulture population and the effect of poison response activities

AbstractVultures in Africa are being poisoned deliberately by poachers to prevent the birds alerting authorities to the poachers’ illegal activities, or for harvesting and sale of body parts for use in witchcraft. Hundreds of vultures can be killed at a single poisoned elephant Loxodonta africana carcass, and although field staff trained in poison response activities can limit the damage, mortalities remain numerous. We used the population viability analysis programme VORTEX to simulate seven 100-year-long scenarios investigating various rates of poisoning mortalities and the remedial effects of poison response activities on a population of Critically Endangered white-backed vultures Gyps africanus breeding in Kruger National Park, South Africa. In six scenarios the population declined (λ &lt; 1); in three scenarios the population remained extant over the 100-year simulations but declined by 60–90% from a starting size of 2,400 individuals. In two scenarios one poisoned elephant carcass left untreated and causing the greatest number of vulture deaths was modelled as a catastrophic event with a 50% probability of annual occurrence, which resulted in a 100% probability of population extinction, with a mean time to extinction of 55–62 years. Effective poison response activities were modelled as a 70% reduction of mortality at each poisoned elephant carcass and resulted in population persistence after 100 years but with a c. 90% reduction in size (final n = 205). We highlight that although poison response activities will not prevent poisoning from occurring, they form an essential part of wider conservation actions designed to prevent local extinctions of vultures or other vulnerable species.

Kalahari vulture declines, through the eyes of meerkats

Vulture populations are experiencing rapid declines across the globe. While the declines have been most precipitous in Asia, recent reports suggest African populations are likewise imminently threatened. As the factors underlying these general population trends are multifaceted and will vary in their relative intensity spatially, it is imperative that monitoring data across different vulture populations is assimilated if targeted conservation action is to prove most effective. In this study, we highlight a medium-term decline in the African White-backed Vulture Gyps africanus population inhabiting the southern Kalahari, South Africa, using a long-term behavioural data set collected from a habituated population of meerkats Suricata suricatta. Meerkats emit an alarm call on sighting airborne vultures, which elicits a group-level response, such that the rates at which this behaviour is recorded in meerkats provides a high-resolution proxy for local vulture abundance. Although unconventional, this sampling method uncovered a steady decline over 17 years in White-backed Vulture numbers that mirrors the temporal decline recently documented in other southern African populations.

Assessing the accuracy of plotless density estimators using census counts to refine population estimates of the vultures of Kruger National Park

Breeding population estimates for three vulture species in Kruger National Park (KNP), South Africa, were made in 2013 using data from aerial censuses and a plotless density estimator (PDE). PDEs are distance-based methods used to assess sparse populations unsuitable for plot-based methods. A correction factor was applied to the 2013 estimates to reflect the difference between the survey counts and the PDE figures. We flew additional censuses across most of KNP and counted all visible nests to assess the 2013 estimates. Survey counts were within 95% confidence limits of corrected PDE estimates for White-backed Vulture Gyps africanus (count: 892; estimate: 904 [95% CI ±162]), at the limit of confidence for White-headed Vulture Trigonoceps occipitalis (count: 48; estimate: 60 [±13]) and outside confidence limits for Lappet-faced Vulture Torgos tracheliotos (count: 44; estimate: 78 [±18]). Uncorrected PDE estimates accurately reflected White-headed and Lappet-faced Vulture nest counts. The clustered patterns of White-backed Vulture nests and dispersed patterns of White-headed and Lappet-faced Vulture nests offer an explanation for these results and means that corrected PDE densities are inaccurate for estimating dispersed nests but accurate for estimating clustered nests. Using PDE methods, aerial surveys over ∼35% of KNP are probably sufficient to assess changes in these vulture populations over time. Our results highlight these globally important breeding populations.

Actual and perceived collision risk for bird strikes at Namibian airports

At Namibia’s two major airports, Hosea Kutako International and Eros (domestic), 117 bird strike collision incidents were recorded between 2006 and 2010. A risk assessment, which included a proposed risk weighting methodology, was conducted at Hosea Kutako and Eros airports, which estimated the probability of an accident/collision as well as the consequence of such a collision. The assessment included surveys of bird occurrence frequencies as well as pilot interviews. The results of the risk assessments were compared with actual bird strike incidences for each species, frequency of occurrence of birds and pilot perceptions of species risk, in order to find whether risk assessment and pilot perception are reliable measures of potential bird strike incidence. White-backed Vulture Gyps africanus and Helmeted Guineafowl Numida meleagris were the highest risk species at both airports. They were also, after Crowned Lapwing Vanellus coronatus, the species most often observed by pilots. Bird strike records showed that Crowned Lapwing and Helmeted Guineafowl were also the most frequently struck birds at both airports. The study illustrates how combining risk assessment, pilot perception and bird strike history can benefit bird strike minimisation plans at airports through the rapid identification of priority bird species.

Hooded Vulture Necrosyrtes monachus and African White-backed Vulture Gyps africanus nesting at the Olifants River Private Nature Reserve, Limpopo province, South Africa

Basic ecological information is still lacking for many species of African vultures. The Hooded Vulture Necrosyrtes monachus is known as a rare breeding resident in north-eastern South Africa. This study set out to monitor the nests of Hooded Vultures and, secondarily, White-backed Vultures Gyps africanus in the Olifants River Private Nature Reserve over two breeding seasons in 2013 and 2014. A total of 12 Hooded Vulture nests, placed mostly in the tree Diospyros mespiliformis, were found along the Olifants River, with an average inter- nest distance of 0.76 km. Nest success was estimated to be between 0.44–0.89 offspring pair−1 y−1 in 2013 and 0.50–0.67 offspring pair−1 y−1 in 2014, which are the first estimates for Hooded Vultures in South Africa. It is thought that nests of this species have been under-reported due to the fact that they are placed within or below the canopy of densely leafed trees and hence difficult to view from aerial surveys. African White-backed Vultures also bred along the Olifants River, with nests placed in clusters of up to six. Nesting density of this species ranged from about 1.0 to 1.2 nests km−1 and nests were predominantly placed in Ficus sycomorus trees.

Trade of threatened vultures and other raptors for fetish and bushmeat in West and Central Africa

AbstractDiurnal raptors have declined significantly in western Africa since the 1960s. To evaluate the impact of traditional medicine and bushmeat trade on raptors, we examined carcasses offered at markets at 67 sites (1–80 stands per site) in 12 countries in western Africa during 1990–2013. Black kite Milvus migrans and hooded vulture Necrosyrtes monachus together accounted for 41% of 2,646 carcasses comprising 52 species. Twenty-seven percent of carcasses were of species categorized as Near Threatened, Vulnerable or Endangered on the IUCN Red List. Common species were traded more frequently than rarer species, as were species with frequent scavenging behaviour (vs non-scavenging), generalist or savannah habitat use (vs forest), and an Afrotropical (vs Palearctic) breeding range. Large Afrotropical vultures were recorded in the highest absolute and relative numbers in Nigeria, whereas in Central Africa, palm-nut vultures Gypohierax angolensis were the most abundant vulture species. Estimates based on data extrapolation indicated that within West Africa 73% of carcasses were traded in Nigeria, 21% in Benin and 5% elsewhere. Offtake per annum in West Africa was estimated to be 975–1,462 hooded vultures, 356–534 palm-nut vultures, 188–282 Rüppell's griffons Gyps rueppellii, 154–231 African white-backed vultures Gyps africanus, 143–214 lappet-faced vultures Torgos tracheliotos, and 40–60 crowned eagles Stephanoaetus coronatus. This represents a sizeable proportion of regional populations, suggesting that trade is likely to be contributing significantly to declines. Stronger commitment is needed, especially by governments in Nigeria and Benin, to halt the trade in threatened raptors and prevent their extirpation.

Vulture populations in Uganda: using road survey data to measure both densities and encounter rates within protected and unprotected areas

SummarySix out of seven vulture species whose global ranges lie largely or wholly within Africa are listed as globally threatened. Since their current distributions individually span up to 39 range states there is a pressing need to develop robust, standardised methods that provide a clear measure of range-wide changes in abundance. Yet, survey methods currently used tend to yield either of two measures: estimates of breeding density, derived mainly from nest counts; or linear encounter rates, derived from road surveys. Here, we present the results of a six-year survey of six vulture species in Uganda, in which we used road counts, in combination with Distance sampling, to determine both encounter rates and densities within protected areas (PAs), and in predominantly pastoral and agricultural areas. In combination, five scavenging species were detected 4–6 times more frequently in PAs than elsewhere, and two species, White-backed Vulture Gyps africanus and Lappet-faced Vulture Torgus tracheliotus, were recorded only within PAs. We estimate that PAs held c.1,300–3,900 individuals of the five scavenging species combined, including c.1,250–2,900 individuals of two Gyps species. We also present national population estimates for two species: White-backed Vulture (c.1,000–2,600 birds) and Lappet-faced Vulture (c.160–500 birds). Although sightings were assigned to only three broad distance bands, Distance sampling provided estimates with a level of precision similar to that achieved for linear encounter rates, but as density estimates; a form more readily comparable with results obtained from other survey types.

Observaciones De Aves Raras En España, 2011

Report on rare birds in Spain 2011. Current report gives details about 452 new records on the presence of 100 rare bird taxa in the whole of Spain. Acceptance index was of 88,94% from a grand total of 579 examined records including pending, duplicated and regional rarities. Details on 12 new taxa for Spain are included for the first time in any rarities report: Asian white-winged scoter Melanitta deglandi, Fea's petrel Pterodroma feae, first and second records, black-bellied storm-petrel Fregetta tropica, eastern imperial eagle Aquila heliaca, sandhill crane Grus canadensis, south polar skua Stercorarius maccormicki, Thayer's Gull Larus thayeri, american hawk-owl Surnia ulula caparoch, buff-bellied pipit Anthus rubescens, eastern black redstart Phoenicurus ochruros phoenicuroides, semicollared flycatcher Ficedula semitorquata and Cretzchsmar's bunting Emberiza caesia. Deserta's petrel, Thayer's gull and hawk owl are new to the Spanish list which was updated in 2012 having considered the rest of the above accepted firsts. The report deals with record numbers of goosander Mergus merganser, buff-breasted sandpiper Tryngites subruficollis and pectoral sandpiper Calidris melanotos besides overwintering episodes of Baird's sandpiper Calidris bairdii and broad-billed sandpiper Limicola falcinellus. Other interesting records are third records for Spain of African white-backed vulture Gyps africanus, upland sandpiper Bartramia longicauda or Baltic gull Larus fuscus fuscus.

Population estimates of three vulture species in Kruger National Park, South Africa

Vultures are globally threatened, yet reliable population data on these birds are few, thus measuring their response to change is difficult. Kruger National Park (KNP) in South Africa is an important stronghold for many avian species, particularly vultures. In this study we generate population estimates for three vulture species in KNP using two plotless density estimators (PDE): a distance estimator based on nearest-neighbour distance and T-square sampling. We flew aerial censuses over large (c. 3 500 km2) sample areas in two ecogeographically separate parts of KNP and counted vulture nests visible within predetermined transects. In total 416 White-backed Vulture Gyps africanus, 22 Lappet-faced Vulture Torgos tracheliotos and 24 White-headed Vulture Trigonoceps occipitalis nests were recorded. The nearest-neighbour distance PDE performed poorly, and we used a T-square PDE calibrated with aerial survey counts to extrapolate across KNP and estimate breeding population sizes. There are an estimated 904 (95% CI±162) pairs of African White-backed Vultures, 78 (95% CI±18) pairs of Lappet-faced Vultures and 60 (95% CI±13) pairs of White-headed Vultures in KNP. These results provide a basis for investigating how large vultures respond to ecosystem change and understanding their resilience within a broader environmental change scenario.

Observaciones de Aves Raras en España, 2009

Summary. Report on rare birds in Spain 2009. This is the 26th annual report of the Spanish rarities committee (Comite de Rarezas de SEO/BirdLife). This report includes 291 records on the presence of 84 rare bird taxa, with an acceptance rate of 75%. The report contains nine additions to the Spanish Bird List: Pacific Loon Gavia pacifica, white-backed vulture Gyps africanus, African purple swamphen Porphyrio porphyrio of the race madagascarensis, hudsonian whimbrel Numenius phaeopus of the race hudsonicus, bridled tern Onychoprion anaethetus, belted kingfisher Megaceryle alcyon, Naumann's thrush Turdus naumanni and black-and-white warbler Mniotilta varia. Having agreed acceptance criteria, the first accepted records of Caspian gull Larus cachinnans registered since 2005 are also included in this report. Second records for Spain of hooded merganser Mergus cucullatus, white wagtail Motacilla alba of the race subpersonata, house bunting Emberiza sahari and of a petrel assigned to the species pair Zino's/Fea's...

Nesting status of African White-backed Vultures Gyps africanus in the Masai Mara National Reserve, Kenya

Vulture populations have declined globally as well as regionally within Africa. Little is known about the status of the African White-backed Vulture Gyps africanus in Kenya, but ongoing studies indicate that its population has declined over the last two decades. A total of 32 African White-backed Vulture nests were monitored in the Masai Mara National Reserve over a five-year period between 2003 and 2007. Mean nesting success was 59%, which is comparable to that of populations from southern Africa. Nearest neighbour distances were significantly closer in wooded habitats (‘trees and shrubs savanna’) than in more open grassland habitats (‘open low shrubs’). Based on nearest neighbour distances, the estimated total breeding population within the Masai Mara National Reserve is 1 106 pairs, a figure that may be an overestimate and requires ground-truthing. Collecting baseline data on numbers of breeding pairs and regular nest monitoring are essential in order to assess the impact of various threats to vultures in Kenya, which include growing threats (elephant-mediated habitat disturbance and fire) as well as emerging threats (such as poisoning with the carbamate-based pesticide Furadan™).

An effect of vegetation structure on carcass exploitation by vultures in an African savanna

Carcass utilisation by vultures may be constrained by the surrounding vegetation, as high vegetation densities may leave insufficient space for the vultures to take-off. We tested this by placing carcasses at 14 sites differing in density and height of the surrounding vegetation. African White-backed Vultures Gyps africanus were reluctant to land at carcasses from which the angle required to clear the surrounding vegetation on take-off was greater than 6°, and Cape Vultures Gyps coprotheres were not observed on carcasses from which the required angle of take-off was greater than 4°. Increasing vegetation densities due to bush encroachment may therefore affect the two species to different extents.