Gyps Coprotheres Research Articles

Conservation buffer sizes derived from movement data of adult Cape vultures (Gyps coprotheres) in South Africa

The endangered Cape vulture (Gyps coprotheres) is facing a new emerging threat, e.g. wind energy development. Given their vulnerability to wind energy infrastructure, there is a necessity to establish proactive measures that could potentially mitigate future collisions, such as conservation buffers around breeding colonies and roost sites. This study used 50% kernel density estimates to estimate conservation potential for conservation buffer zone sizes for colonies. Our results indicate a buffer size of ±50 km to cover the core foraging range of the species around colonies.

Low genetic diversity and shallow population structure in the endangered vulture, Gyps coprotheres

Globally, vulture species are experiencing major population declines. The southern African Cape vulture (Gyps coprotheres) has undergone severe population collapse which has led to a listing of Endangered by the IUCN. Here, a comprehensive genetic survey of G. coprotheres is conducted using microsatellite markers. Analyses revealed an overall reduction in heterozygosity compared to other vulture species that occur in South Africa (Gypaetus barbatus, Necrosyrtes monachus, and Gyps africanus). Bayesian clustering analysis and principal coordinate analysis identified shallow, subtle population structuring across South Africa. This provides some support for regional natal philopatry in this species. Despite recent reductions in population size, a genetic bottleneck was not detected by the genetic data. The G. coprotheres, however, did show a significant deficiency of overall heterozygosity. This, coupled with the elevated levels of inbreeding and reduced effective population size, suggests that G. coprotheres is genetically depauperate. Given that genetic variation is considered a prerequisite for adaptation and population health, the low genetic diversity within G. coprotheres populations is of concern and has implications for the future management and conservation of this species.

Blood and bone lead levels in South Africa's Gyps vultures: Risk to nest-bound chicks and comparison with other avian taxa

Poisoning, including secondary lead poisoning, is cited as the single most important cause of vulture mortalities in Africa. To evaluate the prevalence of lead poisoning among South Africa's Gyps vultures compared to other, non-scavenging birds, we obtained blood and bone samples from Cape (Gyps coprotheres) and White-backed (G. africanus) vultures. We found that 66% of White-backed Vultures (n = 110, including 85 nest-bound chicks sampled at Dronfield Nature Reserve) and 80% of Cape Vultures (n = 15) had blood [Pb] in excess of 10 μg/dL, the upper limit of background exposure. Average blood [Pb] were 15.4 μg/dL and 29.7 μg/dL for White-backed and Cape vultures, respectively. Bone samples revealed that 12% of White-backed Vultures (n = 18) and 9% of Cape Vultures (n = 75) suffered from subclinical to severe clinical lead poisoning upon their deaths. By contrast, none of the 40 blood, bone or liver samples obtained from non-scavenging bird species were found to exceed background exposure levels. Our results suggest that, unlike non-scavenging birds, the scavenging lifestyle of Gyps vultures subjects them to lead poisoning on a regular basis. Had environmental sources of lead (e.g., dust) been the source of the lead poisoning at the White-backed Vulture breeding colony at Dronfield, all the chicks would have displayed similar blood lead concentrations. Instead the values ranged from barely detectable to very high, leading us to conclude that metallic lead fragments regurgitated by parents during feeding are responsible for the elevated lead levels in some of the chicks at this site. We conclude the likely source of these particles to be fragments of lead ammunition embedded in the carcasses of hunted animals. These results add to a growing body of evidence underscoring the threat posed by the use of lead ammunition and its potential role in the declines of vultures and other scavenging taxa.

Percentage of faecal excretion of meloxicam in the Cape vultures (Gyps corprotheres)

Asian Gyps vulture species are gradually recovering from the devastating effect of diclofenac being present in contaminated carcasses. This drug was responsible for the death of over 10 million vultures in India, Nepal and Pakistan. To prevent the extinction of vultures, meloxicam was introduced after the ban of veterinary diclofenac. Meloxicam's safety in vultures was attributed to its short elimination half-life in contrast with diclofenac. The reason for the rapid elimination of meloxicam is yet to be explained. The aim of this study was to evaluate the role of biotransformation in the elimination of meloxicam. Six Cape griffon vultures (Gyps coprotheres) were treated with 2 mg/kg meloxicam intramuscularly for faecal and plasma quantification of meloxicam concentration over time. In the plasma meloxicam was characterised by a half-life, mean residence time, clearance and volume of distribution at steady state of 0.37 ± 0.10 h, 0.90 ± 0.12 h, 0.02 ± 0.00 l/h kg and 0.02 ± 0.00 l/kg respectively (presented as geometric mean). Over the 24 h monitoring period, the total non-metabolised meloxicam in the faeces was 1.35 ± 0.71% of the total concentration in the plasma. Based on the short meloxicam elimination half-life and low cumulative concentration of total faecal meloxicam over a period in excess of 10 half-lives, this study indicates that Cape griffon vultures are efficient metaboliser of meloxicam, which is suggestive of different set of cytochrome enzymes being involved in the metabolism to that for diclofenac in this species. Identification of orthologous human CYP2C9 and CYP3A4 enzyme families in vultures will be an important further step in explaining the differences in the metabolic pathway(s) of meloxicam and diclofenac for the species.

The use of liver slices from the Cape vulture (Gyps coprotheres) to better understand the role of liver toxicity of non-steroidal anti-inflammatory drugs (NSAIDs) in vultures

Diclofenac, a non-steroidal anti-inflammatory drug (NSAID) was responsible for the death of millions of vultures on the Asian subcontinent, following the consumption of diclofenac contaminated carcasses. The aim of this research was to establish if liver slices could serve as an alternate means of predicting the toxicity of NSAIDs in Gyps vultures. The Cape vulture liver slices was prepared and incubated with four NSAIDs for 6 h. A percent clearance of 1.0 ± 0.253, 0.58 ± 0.153, 0.961 ± 0.312 and 1.242 ± 0.406 (%/h*g) was attained for diclofenac, carprofen, ketoprofen and meloxicam respectively. Both meloxicam and diclofenac exerted toxic effects on the hepatic cells. Protein content indicated that the vulture tissue had lower enzyme levels than expected for an animal of its size. The poor distinction between the ex vivo hepatic percent clearance of meloxicam and diclofenac indicates that liver slices is not an ideal model to investigate NSAIDs toxicity in Cape vulture.

Post-fledging movement and spatial ecology of the endangered Cape Vulture (Gyps coprotheres)

The post-fledging dependence period (PFDP) is one of the most critical stages in the life history of some avian species. Birds are particularly sensitive to mortality during this stage as they must learn essential skills, such as efficient locomotion, proficient food location and predator avoidance. Knowledge of the PFDP would provide valuable information for conservation management of endangered species, many of which experience high juvenile fatality rates. Post-fledging movements of five endangered Cape Vultures were recorded using Global Positioning System/Global System for Mobile communication telemetry in South Africa. Home range sizes, distances travelled from the nest and habitat use were determined over 11 months during the PFDP. Fledglings increased their home range progressively for the first 2 months, then exhibited a rapid increase in home range size associated with dispersal from their natal colony. Maximum net daily distance also rapidly increased following the dispersal period. A preference for protected areas and woody vegetation (representing cliff faces used for roosting) in terms of habitat use for foraging was evident. The knowledge of the movement and habitat use of juvenile Cape Vultures can aid in the effective conservation planning for the species. Conservation programs in identified areas can be focused on power line and wind-farm mitigation, areas of supplementary feeding and anti-poisoning events.

Sexing Cape Vulture Gyps coprotheres based on head morphometrics

The Cape Vulture Gyps coprotheres is considered sexually monomorphic in the literature, but visual differences in head shape between the sexes have been observed. Furthermore, head morphometrics of other Gyps species show statistically significant variation between the sexes. We show that head morphometrics can be used to determine the sex of Cape Vultures. Males generally have wider and shorter heads, and larger bill depths than females. Discriminant function analysis with data from 63 individuals identified the three most predictive variables in sex determination to be head width, head length and bill depth. We also provide an equation that can be used in conjunction with head measurements as a method to determine the sex of Cape Vultures in the field with an overall accuracy of 84% (92% accuracy for females and 72% for males).

Sexual dimorphism and plumage characteristics of juvenile Cape Vultures Gyps coprotheres

The plumage of young Cape Vultures Gyps coprotheres is streaked to varying degrees on the breast, ruff and upper wing coverts. Observations of breast plumage (individual feather streak coverage and overall streaking intensity) were made on Cape Vultures aged one to six years old. Juveniles, or birds in their first year, were genetically sexed. Standardised photographs were taken of plucked juvenile breast feathers and analysed using Adobe Photoshop. Pixel counts were taken to analyse the streak coverage of a single feather. A scale from 0 to 3 was used to score streak intensity of the entire breast. We determined that breast streaking can be used as a reliable sexing technique with males being more heavily streaked than females. However, streaking is quickly lost with age and is therefore likely only to be a significant sexing tool for juveniles. The streaking of the breast generally disappears by four years of age.

SAFRING longevity and movement records for southern African vultures (subfamilies Aegypiinae and Gypaetinae)

Longevity and displacement records aid in the understanding of animal senescence and the possible range of a species. Within wild populations this information is infrequent with most longevity reports being based on captive individuals and displacements being calculated from few monitored individuals within the population. Ringing offers a means of calculating these values and for avian species SAFRING and other bird ringing schemes are critically important. As many vulture populations are under threat, it has become ever more important to analyse all aspects of their demography to understand what can be done to aid the conservation of these species. Southern Africa’s eight vulture species are almost all listed as globally threatened and as a result many studies incorporate this ringing information. This has allowed for longevity records to be calculated for most of the species with the Cape Vulture obtaining the greatest reported longevity of 31 years 2 months and 14 days. In addition to the longevity records, ringing also produces maximum displacement records with the greatest vulture displacement being 2 530 km (White-backed Vulture). Although vulture ringing effort has improved in recent years very few new longevity records appear to be produced with most recent recoveries being under 10 years.

High occurrence of extra-pair partnerships and homosexuality in a captive Cape Vulture Gyps coprotheres colony

The Cape Vulture Gyps coprotheres is an Endangered colonial cliff-nesting species that is typically cited as monogamous. Observations of wild Cape Vulture colonies note extra-pair breeding activities but homosexual activity has never been confirmed. Observations of breeding behaviours within a captive colony were conducted at VulPro’s breeding facilities in South Africa The captive breeding programme included 10 breeding pairs and a total of 41 non-releasable, individually recognisable, and genetically sexed subadults or adults. Observations were conducted over the 2014 breeding season as part of a study investigating the social and rearing conditions of chicks intended for release in a population supplementation programme. A high percentage of total colony copulation attempts (22%) were extra-pair copulations but only 23 interactions resulted in cloacal contact or possible sperm transfer. Four paired males formed extra-pair relationships, two of which were homosexual.

Due South: A first assessment of the potential impacts of climate change on Cape vulture occurrence

Multiple anthropogenic threats have caused vulture populations to decline globally, with serious ecological and socio-economic implications. The Cape vulture (Gyps coprotheres) has declined throughout its range in southern Africa, recently being listed as extinct as a breeding species in Namibia. It has been suggested that climate change might have contributed to the decline of Cape vultures in northern parts of the range. To provide a first assessment of the potential impacts of climate change on the occurrence of Cape vultures, a presence-only environmental niche modelling method (Maxent) was used to predict the spatial occurrence patterns of wild vultures fitted with GPS tracking units in northern Namibia and northern South Africa, under current and future climatic conditions. The models showed high predictive power (AUC >0.868±0.006), with precipitation seasonality identified as the most important variable for predicting Cape vulture presence. Of the area estimated to be suitable for Cape vultures under current conditions, 28–55% was predicted to become unsuitable under future climate conditions, with a pole-ward shift in the mean centre of the range of 151–333 km and significant range loss from the former breeding range in north-central Namibia and the core breeding range in northern South Africa. The total area of suitable range was predicted to increase in the future due to modelled expansions into grassland and cropland areas where the species has been absent historically. The coverage of suitable areas by protected areas was predicted to decrease from 5.8–7.9% to 2.8–3.8%, suggesting that private land will become increasingly important for Cape vulture conservation.

Observations of microtrash ingestion in Cape Vultures in the Eastern Cape, South Africa

Ingestion of man-made items by birds can reduce stomach volume and block the digestive track. In southern Africa, microtrash within the regurgitation of Cape Vulture nestlings was last documented in 1983. We present evidence of nestling microtrash ingestion after a 30-year gap. Vulture nestlings were captured at a breeding colony in the Eastern Cape, South Africa. One nestling regurgitated three microtrash fragments. Two pieces of microtrash were collected from the nest of another nestling. Neither nestling appeared to have skeletal deformities or feather stress bars. Our results highlight the persistence of microtrash ingestion by Cape Vulture nestlings, which could impact the species negatively.

Natal philopatry in young Cape Vultures Gyps coprotheres

In 2010, 14 Cape Vulture Gyps coprotheres chicks were ringed as nestlings on the cliffs at the Skeerpoort Cape Vulture colony in the Magaliesberg mountains, South Africa. Observations made during the 2014 and 2015 breeding colony censuses confirm two individuals returned to the Magaliesberg to breed. One female bred at Skeerpoort while another female settled in the Nooitgedacht colony situated 25 km from her natal nest. Breeding attempts occurred at four years old for both individuals, the youngest on record for wild Cape Vultures. One individual successfully raised a fledgling.

Cliff characteristics, neighbour requirements and breeding success of the colonial Cape VultureGyps coprotheres

The breeding success of endangered colonial nesting species is important for their conservation. Many species ofGypsvultures form large breeding colonies that are the foci of conservation efforts. The Cape Vulture is a globally threatened species that is endemic to southern Africa and has seen a major reduction in its population size (≥ 50% over 48 years). There is evidence that breeding colonies are prone to desertion as a result of human disturbance. Factors that influence the occupancy and breeding success of individual nest‐sites is not fully understood for any African vulture species. We investigated cliff characteristics and neighbour requirements of the Msikaba Cape Vulture colony, a major breeding colony in the southern node of the population in the Eastern Cape, South Africa, together with their nest‐site occupation and breeding success over 13 years. In total, 1767 breeding attempts were recorded. Nest‐sites that had a higher elevation, smaller ledge depth, greater total productivity and were surrounded by conspecifics were more likely to be occupied, although the amount of overhang above the nest was not an important predictor of occupancy. In accordance with occupation, nest‐sites with a smaller ledge depth had higher breeding success; however, nests with a greater overhang were also more successful and height of the nest‐site was not an important predictor of breeding success. The breeding success of a nest‐site in a given year was positively influenced by the number of direct nest neighbours, and nests in the middle of high‐density areas had greater breeding success. This suggests that maintaining a high nest density may be an important consideration if declines of reproducing adults continue. Breeding success declined over the study period, highlighting the effects of a temporal variation or observer bias. Our results identified optimal nest‐site locations (ledge depths of 1 m, at a height of 180 m) and their effects on breeding success. This information can be used for planning reintroduction efforts of the endangered Cape Vulture and for their ongoing conservation.

Lead ingestion as a potential contributing factor to the decline in vulture populations in southern Africa

Vulture populations in southern Africa have been on the decline for years, which unlike the Asian vulture crisis, has no one specific cause. Reasons attributable are deliberate and secondary poisonings, drowning, power line injuries, electrocutions, traditional medicine (“muti” trade) and calcium deficiencies. However, lead toxicity as a potential causal factor is hardly mentioned. The potential for lead toxicity needs to be considered as substantial game hunting occurs in the region with little regulatory control on bullet types. In this study, we determined the whole blood lead concentrations of captive and wild vulture populations in South Africa and Namibia (n=185). Results were compared to previous published ranges indicative of background exposure (<10μg/dL), non-toxic point exposure based upon the range established from captive birds and subclinical exposure. In general, whole blood lead concentrations were higher for wild African White-backed vultures (Gyps africanus)(AWBV) than Cape vultures (G. coprotheres)(CGV) at 15.54±12.63μg/dL vs 12.53±8.88μg/dL (non-significantly different), while in the Bearded vultures (Gypaetus barbatus) no indication of exposure was evident. Very similar exposures resulted irrespective of the birds being in captivity or under wild, free-roaming conditions. A proportion of wild birds did, however, appear to be exposed to another source of lead than purely environmental (±12% and 30.6% for AWBV and CGV respectively). One bird, which had a whole blood concentration of 100μg/dL, died soon after capture. To find the relationship between whole blood lead concentration and likely exposure factors, birds were compared by their rural/urban location, vicinity to mines and surrounding soil lead concentrations. With no relationship being present for the latter factors, we believe that this is evidence that the portion of southern African vultures being exposed to unknown source of lead, which we suggest arises from leaded ammunition remaining from hunting

Long-term data indicates that supplementary food enhances the number of breeding pairs in a Cape VultureGyps coprotherescolony

SummaryThe number of vultures is declining in many parts of the world due to numerous threats, such as poisoning and collisions with power-lines as well as the lack of adequate food sources. Vulture restaurants, i.e. supplementary feeding stations, have become a widespread conservation tool aimed at supporting vulture colonies. However, it is poorly understood how vulture restaurants influence population dynamics and whether they affect breeding success of vulture populations. We used a 12-year dataset from a breeding colony of the Cape VultureGyps coprotheresand a nearby vulture restaurant in South Africa to investigate the effect of supplementary food on population dynamics and breeding success. We found a significantly positive effect of supplementary food during the nest-building stage on the number of breeding pairs. However, breeding success, i.e. the proportion of successful nests, did not depend on supplementary food during the incubation and rearing stage. Especially during the critical rearing stage, the amount of food supplied might not have been sufficient to meet food demands of the colony. Still, our results indicate that carefully managed vulture restaurants might stabilise vulture colonies and can therefore aid vulture conservation.

Home range and habitat selection of Cape Vultures Gyps coprotheres in relation to supplementary feeding

ABSTRACTCapsule: Supplementary feeding stations provide a useful conservation benefit for vultures, without disrupting their natural movement ecology.Aims: To understand the effects of providing supplementary food on the movement ecology of vultures.Methods: We used Global Positioning System tracking devices to monitor the movements of 28 Cape Vultures Gyps coprotheres using feeding stations in South Africa. We calculated home range values and then performed a habitat selection analysis.Results: We show that aside from roost sites, vulture feeding stations are the most important environmental variable that explains vulture movements. However, we found that the birds ranged over areas without supplementary food and their mean home range values were comparable to those measured before the inception of feeding stations.Conclusion: Our findings suggest that the use of supplementary feeding sites did not significantly impact on the natural foraging behaviour of the species.

Cape Vulture Gyps coprotheres breeding status in southern Africa: monitoring results from 2010–2014

Monitoring of eight Cape Vulture Gyps coprotheres breeding colonies in South Africa and Botswana took place between 2010 and 2014 using standardised counting methods. Counts of breeding pairs, nestlings and fledglings were used to calculate breeding success and general population trends. While our data suggests multiple colonies are stable or increasing, the extinction of peripheral colonies and contraction of the species’ range is alarming and gives evidence for unsustainable population declines. Monitoring efforts chronicled the extinction of the previously large core colony at Roberts’ Farm, which was abandoned as a breeding site in 2013. Standardised monitoring is urgently needed across the entire species range to better understand current population dynamics.

Serum and Plasma Cholinesterase Activity in the Cape Griffon Vulture (Gyps coprotheres)

Vulture (Accipitridae) poisonings are a concern in South Africa, with hundreds of birds dying annually. Although some of these poisonings are accidental, there has been an increase in the number of intentional baiting of poached rhinoceros (Rhinocerotidae) and elephant (Elephantidae) carcasses to kill vultures that alert officials to poaching sites by circling overhead. The primary chemicals implicated are the organophosphorous and carbamate compounds. Although most poisoning events can be identified by dead vultures surrounding the scavenged carcass, weak birds are occasionally found and brought to rehabilitation centers for treatment. The treating veterinarian needs to make an informed decision on the cause of illness or poisoning prior to treatment. We established the reference interval for serum and plasma cholinesterase activity in the Cape Griffon Vulture ( Gyps coprotheres ) as 591.58-1,528.26 U/L, providing a clinical assay for determining potential exposure to cholinesterase-depressing pesticides. Both manual and automated samplers were used with the butyrylthiocholine method. Species reference intervals for both serum and plasma cholinesterase showed good correlation and manual and automated measurements yielded similar results.

Confirmed organophosphorus and carbamate pesticide poisonings in South African wildlife (2009-2014).

During a six-year period (from January 2009 to December 2014), specimens collected from 344 cases of suspected organophosphorus and carbamate pesticide poisonings in wildlife, including birds, were submitted to the Toxicology Laboratory (ARC-OVI) for analysis. A positive diagnosis was made in 135 (39%) of these cases. The majority of cases were from birds, which included Cape vultures (Gyps coprotheres) and African white-backed vultures (Gyps africanus) and bateleur eagles (Terathopius ecaudatus). In one incident 49 vultures were killed when a farmer intentionally laced carcasses with carbofuran in an attempt to control jackal predation. There were 22 incidents of poisoning in helmeted guineafowl (Numida meleagris). On nine different occasions blue cranes (Anthropoides paradiseus) were poisoned, in one incident 14 birds were reported to have been killed. Over the period of investigation, there were 20 cases of poisoning involving mammalian species, the majority being vervet monkeys (Chlorocebus pygerythrus). The carbamate pesticides were responsible for 57 incidents of poisoning. Aldicarb, carbofuran and methomyl were detected in 26, 18 and 12 cases respectively. The majority of organophosphorus pesticide poisonings were caused by diazinon (n = 19), monocrotophos (n = 13) and methamidophos (n = 10).