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Nyirenda VR, Nkhata BA, Phiri D, Nyirenda W, Phiri DN, Malasa M, Becker MS, Tembo EM, Nyirenda MA, Simpamba T, Mwitwa J, Chomba C. Vulture poisoning in Sub-Saharan Africa and its implications for conservation planning: A systematic review. Heliyon 2024; 10:e25126. [PMID: 38333820 PMCID: PMC10850522 DOI: 10.1016/j.heliyon.2024.e25126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 01/13/2024] [Accepted: 01/21/2024] [Indexed: 02/10/2024] Open
Abstract
The Old World Vultures (OWV), constituting 16 species primarily in Africa, Europe and Asia, are currently being driven to extinction mostly by anthropogenic activities, especially poisoning. The vulture losses from poisoning caused by human-related activities are en masse at a single mortality event-level and occur in complex social-ecological systems. There has been a growing body of knowledge on wildlife poisoning over the years. However, no review has been done to consolidate vulture poisoning studies in sub-Saharan Africa (SSA), with a social lens of conservation planning. Here we present a review of the vulture poisoning research by re-contextualizing the problem of vulture poisoning across SSA. We employed stepwise Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method to search for literature on vulture poisoning. The search yielded 211 studies which were trimmed to 55 after applying sets of eligibility criteria. Literature shows that efforts aimed at successful vulture conservation planning will require an understanding of the relational aspects of stakeholder social capital (assets) that are critical to the implementation of species recovery strategies. Strengthening relational social capital through multi-scale stakeholder evidence-based awareness creation and participation is necessary for addressing the African Vulture Crisis (AVC). Applying stakeholder social capital approaches to different vulture conservation scenarios at local, regional and international scales can enhance successful implementation of conservation strategies for the persistence of vultures in complex socio-ecological systems in African landscapes. Existing literature also showed the importance of stakeholder social capital as a countermeasure against vulture losses.
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Affiliation(s)
- Vincent Raphael Nyirenda
- Department of Zoology and Aquatic Sciences, School of Natural Resources, The Copperbelt University, Jambo Drive, Riverside, P.O. Box 21692, Kitwe, Zambia
| | - Bimo Abraham Nkhata
- University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa
| | - Darius Phiri
- Plant and Environmental Sciences, School of Natural Resources, The Copperbelt University, Jambo Drive, Riverside, P.O. Box 21692, Kitwe, Zambia
| | - Wilfred Nyirenda
- Department of Clinical Sciences, School of Medicine, The Copperbelt University, P.O. Box 21692, Ndola, Zambia
| | | | - Mary Malasa
- BirdWatch Zambia, 25 Joseph Mwilwa Road, Rhodes Park, P.O. Box 33944, Lusaka, Zambia
| | | | - Enala Mwase Tembo
- Department of Paraclinical Studies, School of Veterinary Medicine, University of Zambia, P.O. Box 32379, Lusaka, Zambia
| | - Moses Amos Nyirenda
- Worldwide Fund for Nature Conservation, Los Angeles Boulevard, P.O. Box 50551 RW, Long acres, Lusaka, Zambia
| | | | - Jacob Mwitwa
- Kapasa Makasa University, P.O. Box 480195, Chinsali, Zambia
| | - Chansa Chomba
- Department of Natural Resources and Environmental Sciences, School of Agriculture and Natural Resources, Mulungushi University, P.O. Box 80415, Kabwe, Zambia
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Kendall CJ, Bracebridge C, Lynch EC, Mgumba M, Monadjem A, Nicholas A, Kane A. Value of combining transect counts and telemetry data to determine short-term population trends in a globally threatened species. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2023; 37:e14146. [PMID: 37424360 DOI: 10.1111/cobi.14146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 06/20/2023] [Accepted: 06/21/2023] [Indexed: 07/11/2023]
Abstract
To evaluate conservation interventions, it is necessary to obtain reliable population trends for short (<10 years) time scales. Telemetry can be used to estimate short-term survival rates and is a common tool for assessing population trends, but it has limitations and can be biased toward specific behavioral traits of tagged individuals. Encounter rates calculated from transects can be useful for assessing changes across multiple species, but they can have large confidence intervals and be affected by variations in survey conditions. The decline of African vultures has been well-documented, but understanding of recent trends is lacking. To examine population trends, we used survival estimates from telemetry data collected over 6 years (primarily for white-backed vultures [Gyps africanus]) and transect counts conducted over 8 years (for 7 scavenging raptors) in 3 large protected areas in Tanzania. Population trends were estimated using survival analysis combined with the Leslie Lefkovitch matrix model from the telemetry data and using Bayesian mixed effects generalized linear regression models from the transect data. Both methods showed significant declines for white-backed vultures in Ruaha and Nyerere National Parks. Only telemetry estimates suggested significant declines in Katavi National Park. Encounter rates calculated from transects also showed declines in Nyerere National Park for lappet-faced vultures (38% annual declines) and Bateleurs (18%) and in Ruaha National Park for white-headed vultures (Trigonoceps occipitalis) (19%). Mortality rates recorded and inferred from telemetry suggested that poisoning is prevalent. However, only 6 mortalities of the 26 presumed mortalities were confirmed to be caused by poisoning, highlighting the challenges of determining the cause of death when working across large landscapes. Despite declines, our data provide evidence that southern Tanzania has higher current encounter rates of African vultures than elsewhere in East Africa. Preventing further declines will depend greatly on mitigating poisoning. Based on our results, we suggest that the use of multiple techniques improves understanding of population trends over the short term.
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Affiliation(s)
- Corinne J Kendall
- Conservation, Education and Science, North Carolina Zoo, Asheboro, North Carolina, USA
- Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, USA
| | - Claire Bracebridge
- Conservation, Education and Science, North Carolina Zoo, Asheboro, North Carolina, USA
| | - Emily C Lynch
- Conservation, Education and Science, North Carolina Zoo, Asheboro, North Carolina, USA
| | - Msafiri Mgumba
- Wildlife Conservation Society, Ruaha-Katavi Landscape Program, Tanzania
| | - Ara Monadjem
- Department of Biological Sciences, University of Eswatini, Kwaluseni, Eswatini
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Hatfield, Pretoria, South Africa
| | - Aaron Nicholas
- Wildlife Conservation Society, Ruaha-Katavi Landscape Program, Tanzania
| | - Adam Kane
- School of Biology and Environmental Science and Earth Institute, O'Brien Science Centre West, University College Dublin Belfield, Dublin, Ireland
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3
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Johnson TF, Murn C. Testing the importance of individual nest‐site selection for a social and group‐living vulture. Afr J Ecol 2022. [DOI: 10.1111/aje.13076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
| | - Campbell Murn
- Hawk Conservancy Trust Andover UK
- School of Biological Sciences University of Reading Reading UK
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Krüger SC, Botha A, Bowerman W, Coverdale B, Gore ML, van den Heever L, Shaffer LJ, Smit-Robinson H, Thompson LJ, Ottinger MA. Old World Vultures Reflect Effects of Environmental Pollutants Through Human Encroachment. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2022; 41:1586-1603. [PMID: 35673892 DOI: 10.1002/etc.5358] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 10/12/2021] [Accepted: 04/28/2022] [Indexed: 06/15/2023]
Abstract
African wildlife face challenges from many stressors including current and emerging contaminants, habitat and resource loss, poaching, intentional and unintentional poisoning, and climate-related environmental change. The plight of African vultures exemplifies these challenges due to environmental contaminants and other stressors acting on individuals and populations that are already threatened or endangered. Many of these threats emanate from increasing human population size and settlement density, habitat loss from changing land use for agriculture, residential areas, and industry, and climate-related changes in resource availability. Environmental chemicals that are hazardous include legacy chemicals, emerging chemicals of concern, and high-volume-use chemicals that are employed as weed killers and in other agricultural applications. Furthermore, there are differences in risk for species living in close proximity to humans or in areas affected by habitat loss, climate, and industry. Monitoring programs are essential to track the status of nesting pairs, offspring survival, longevity, and lifetime productivity. This is important for long-lived birds, such as vultures, that may be especially vulnerable to chronic exposure to chemicals as obligate scavengers. Furthermore, their position in the food web may increase risk due to biomagnification of chemicals. We review the primary chemical hazards to Old World vultures and the interacting stressors affecting these and other birds. Habitat is a major consideration for vultures, with tree-nesters and cliff-nesters potentially experiencing different risks of exposure to environmental chemicals. The present review provides information from long-term monitoring programs and discusses a range of these threats and their effects on vulture populations. Environ Toxicol Chem 2022;41:1586-1603. © 2022 SETAC.
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Affiliation(s)
- Sonja C Krüger
- Ezemvelo KZN Wildlife, Scientific Services, Cascades, South Africa
- Centre for Functional Biodiversity, School of Life Sciences, University of KwaZulu-Natal, Scottsville, South Africa
| | - Andre Botha
- Endangered Wildlife Trust, Midrand, South Africa
| | - William Bowerman
- Department of Environmental Science and Technology, University of Maryland, College Park, Maryland, USA
| | - Brent Coverdale
- Ezemvelo KZN Wildlife, Scientific Services, Cascades, South Africa
| | - Meredith L Gore
- Department of Geographical Sciences, University of Maryland, College Park, Maryland, USA
| | | | - L Jen Shaffer
- Department of Anthropology, University of Maryland, College Park, Maryland, USA
| | - Hanneline Smit-Robinson
- BirdLife South Africa, Johannesburg, South Africa
- Applied Behavioural Ecological & Ecosystem Research Unit, University of South Africa, Florida, South Africa
| | - Lindy J Thompson
- Centre for Functional Biodiversity, School of Life Sciences, University of KwaZulu-Natal, Scottsville, South Africa
- Endangered Wildlife Trust, Midrand, South Africa
| | - Mary Ann Ottinger
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA
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Zvidzai M, Zengeya FM, Masocha M, Ndaimani H, Murwira A. Application of GPS occurrence data to understand African white-backed vultures Gyps africanus spatial home range overlaps. Ecol Evol 2022; 12:e8778. [PMID: 35386881 PMCID: PMC8976281 DOI: 10.1002/ece3.8778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 03/01/2022] [Accepted: 03/13/2022] [Indexed: 11/07/2022] Open
Abstract
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.
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Affiliation(s)
- Mark Zvidzai
- Department of Geography and Environmental ScienceUniversity of ZimbabweHarareZimbabwe
| | | | - Mhosisi Masocha
- Department of Geography and Environmental ScienceUniversity of ZimbabweHarareZimbabwe
| | - Henry Ndaimani
- Department of Geography and Environmental ScienceUniversity of ZimbabweHarareZimbabwe
| | - Amon Murwira
- Department of Geography and Environmental ScienceUniversity of ZimbabweHarareZimbabwe
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A conservation criminology-based desk assessment of vulture poisoning in the Great Limpopo Transfrontier Conservation Area. Glob Ecol Conserv 2020. [DOI: 10.1016/j.gecco.2020.e01076] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Fuentes-Castillo D, Esposito F, Cardoso B, Dalazen G, Moura Q, Fuga B, Fontana H, Cerdeira L, Dropa M, Rottmann J, González-Acuña D, Catão-Dias JL, Lincopan N. Genomic data reveal international lineages of critical priority Escherichia coli harbouring wide resistome in Andean condors (Vultur gryphus Linnaeus, 1758). Mol Ecol 2020; 29:1919-1935. [PMID: 32335957 DOI: 10.1111/mec.15455] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 04/01/2020] [Accepted: 04/16/2020] [Indexed: 12/18/2022]
Abstract
Critical priority pathogens have globally disseminated beyond clinical settings, thereby threatening wildlife. Andean Condors (Vultur gryphus) are essential for ecosystem health and functioning, but their populations are globally near threatened and declining due to anthropogenic activities. During a microbiological and genomic surveillance study of critical priority antibiotic-resistant pathogens, we identified pandemic lineages of multidrug-resistant extended-spectrum β-lactamase (ESBL)-producing Escherichia coli colonizing Andean Condors admitted at two wildlife rehabilitation centres in South America. Genomic analysis revealed the presence of genes encoding resistance to hospital and healthcare agents among international E. coli clones belonging to sequence types (STs) ST162, ST602, ST1196 and ST1485. In this regard, the resistome included genes conferring resistance to clinically important cephalosporins (i.e., CTX-M-14, CTX-M-55 and CTX-M-65 ESBL genes), heavy metals (arsenic, mercury, lead, cadmium, copper, silver), pesticides (glyphosate) and domestic/hospital disinfectants, suggesting a link with anthropogenic environmental pollution. On the other hand, the presence of virulence factors, including the astA gene associated with outbreak of childhood diarrhoea and extra-intestinal disease in animals, was identified, whereas virulent behaviour was confirmed using the Galleria mellonella infection model. E. coli ST162, ST602, ST1196 and ST1485 have been previously identified in humans and food-producing animals worldwide, indicating that a wide resistome could contribute to rapid adaptation and dissemination of these clones at the human-animal-environment interface. Therefore, these results highlight that Andean Condors have been colonized by critical priority pathogens, becoming potential environmental reservoirs and/or vectors for dissemination of virulent and antimicrobial-resistant bacteria and/or their genes, in associated ecosystems and wildlife.
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Affiliation(s)
- Danny Fuentes-Castillo
- Department of Pathology, School of Veterinary Medicine and Animal Sciences, University of São Paulo, Sao Paulo, Brazil
| | - Fernanda Esposito
- Department of Clinical Analysis, Faculty of Pharmacy, University of São Paulo, Sao Paulo, Brazil
| | - Brenda Cardoso
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Sao Paulo, Brazil
| | - Gislaine Dalazen
- Department of Pathology, School of Veterinary Medicine and Animal Sciences, University of São Paulo, Sao Paulo, Brazil
| | - Quézia Moura
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Sao Paulo, Brazil
| | - Bruna Fuga
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Sao Paulo, Brazil
| | - Herrison Fontana
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Sao Paulo, Brazil
| | - Louise Cerdeira
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Sao Paulo, Brazil
| | - Milena Dropa
- School of Public Health, University of São Paulo, Sao Paulo, Brazil
| | | | - Daniel González-Acuña
- Department of Animal Sciences, Faculty of Veterinary Sciences, University of Concepción, Chillán, Chile
| | - José L Catão-Dias
- Department of Pathology, School of Veterinary Medicine and Animal Sciences, University of São Paulo, Sao Paulo, Brazil
| | - Nilton Lincopan
- Department of Clinical Analysis, Faculty of Pharmacy, University of São Paulo, Sao Paulo, Brazil.,Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Sao Paulo, Brazil
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8
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Brink CW, Santangeli A, Amar A, Wolter K, Tate G, Krüger S, Tucker AS, Thomson RL. Quantifying the spatial distribution and trends of supplementary feeding sites in South Africa and their potential contribution to vulture energetic requirements. Anim Conserv 2020. [DOI: 10.1111/acv.12561] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- C. W. Brink
- FitzPatrick Institute of African Ornithology DST‐NRF Centre of Excellence University of Cape Town Cape Town South Africa
| | - A. Santangeli
- FitzPatrick Institute of African Ornithology DST‐NRF Centre of Excellence University of Cape Town Cape Town South Africa
- The Helsinki Lab of Ornithology Finnish Museum of Natural History University of Helsinki Helsinki Finland
| | - A. Amar
- FitzPatrick Institute of African Ornithology DST‐NRF Centre of Excellence University of Cape Town Cape Town South Africa
| | | | - G. Tate
- Birds of Prey Programme Endangered Wildlife Trust Modderfontein South Africa
| | - S. Krüger
- Ezemvelo KwaZulu‐Natal Wildlife Cascades South Africa
| | | | - R. L. Thomson
- FitzPatrick Institute of African Ornithology DST‐NRF Centre of Excellence University of Cape Town Cape Town South Africa
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9
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Hilbers JP, Huijbregts MAJ, Schipper AM. Predicting reintroduction costs for wildlife populations under anthropogenic stress. J Appl Ecol 2019. [DOI: 10.1111/1365-2664.13523] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jelle P. Hilbers
- Department of Environmental Science Institute for Wetland and Water Research Faculty of Science Radboud University Nijmegen Nijmegen The Netherlands
| | - Mark A. J. Huijbregts
- Department of Environmental Science Institute for Wetland and Water Research Faculty of Science Radboud University Nijmegen Nijmegen The Netherlands
| | - Aafke M. Schipper
- Department of Environmental Science Institute for Wetland and Water Research Faculty of Science Radboud University Nijmegen Nijmegen The Netherlands
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10
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Plaza PI, Martínez-López E, Lambertucci SA. The perfect threat: Pesticides and vultures. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 687:1207-1218. [PMID: 31412456 DOI: 10.1016/j.scitotenv.2019.06.160] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 06/06/2019] [Accepted: 06/10/2019] [Indexed: 06/10/2023]
Abstract
Probably the most important threat currently affecting vultures worldwide is exposure to pesticides, both accidentally and through deliberate abuse. This is of special concern since around 70% of vulture species are threatened by human activities. However, information about this threat is sparse and geographically biased. We compiled existing knowledge about pesticide exposure in vulture species globally, providing unifying criteria to mitigate this problem with a joint global effort. Most information available about accidental exposure to pesticides in vultures is related to organochlorine pesticides. Non-lethal exposure to these compounds occurs on every continent that vultures inhabit. While concentrations of organochlorine pesticides reported in different samples appear to be too low to produce health impacts, some studies show vultures with levels compatible with health impacts. In addition, there are some reports of vultures contaminated accidentally by anticoagulant rodenticides and external antiparasitic drugs used in veterinary practices. Deliberate abuse of pesticides to poison wildlife also occurs on every continent where vultures live, affecting most (78%) vulture species. However, little information is available for some regions of America, Asia and Europe. The exact number of vultures killed due to deliberate poisoning with pesticides is not well known, but the available figures are alarming (e.g. up to 500 individuals in a single event). The most widely used pesticides affecting vulture populations, and associated with deliberate poisoning, are carbamates and organophosphorus compounds. Of particular concern is the fact that massive poisoning events with these compounds occur, in some cases, within protected areas. This suggests that if this situation is not reversed, some vulture populations could disappear. A combination of measures such as banning pesticides, controlling their distribution-acquisition and environmental education could produce better results that banning pesticides alone. If poisoning with pesticides is not stopped, this threatened avian group could inadvertently go extinct very soon.
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Affiliation(s)
- Pablo I Plaza
- Grupo de Investigaciones en Biología de la Conservación, Laboratorio Ecotono, INIBIOMA (Universidad Nacional del Comahue - CONICET), Quintral 1250 (R8400FRF), San Carlos de Bariloche, Argentina.
| | - Emma Martínez-López
- Area of Toxicology, Department of Health Sciences, Faculty of Veterinary, University of Murcia, Campus de Espinardo, 30100 Murcia, Spain; Laboratory of Toxicology, Biomedical Research Institute of Murcia (IMIB-Arrixaca), University of Murcia, Spain
| | - Sergio A Lambertucci
- Grupo de Investigaciones en Biología de la Conservación, Laboratorio Ecotono, INIBIOMA (Universidad Nacional del Comahue - CONICET), Quintral 1250 (R8400FRF), San Carlos de Bariloche, Argentina
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11
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van den Heever L, Smit-Robinson H, Naidoo V, McKechnie AE. Blood and bone lead levels in South Africa's Gyps vultures: Risk to nest-bound chicks and comparison with other avian taxa. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 669:471-480. [PMID: 30884269 DOI: 10.1016/j.scitotenv.2019.03.123] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 03/08/2019] [Accepted: 03/08/2019] [Indexed: 06/09/2023]
Abstract
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.
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Affiliation(s)
- Linda van den Heever
- Terrestrial Bird Conservation Programme, BirdLife South Africa, Private Bag X16, Pinegowrie, Johannesburg 2123, South Africa; DST-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa.
| | - Hanneline Smit-Robinson
- Terrestrial Bird Conservation Programme, BirdLife South Africa, Private Bag X16, Pinegowrie, Johannesburg 2123, South Africa; Applied Behavioural Ecological & Ecosystem Research Unit (ABEERU), UNISA, P O Box 392, UNISA 0003, Florida, South Africa; School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, Wits, Johannesburg 2050, South Africa.
| | - Vinny Naidoo
- Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa.
| | - Andrew E McKechnie
- DST-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa; National Zoological Garden, South African National Biodiversity Institute, P O Box 754, Pretoria 0001, South Africa.
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