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Gil-Sánchez JM, Rodríguez-Caro RC, Moleón M, Martínez-Pastor MC, León-Ortega M, Eguía S, Graciá E, Botella F, Sánchez-Zapata JA, Martínez-Fernández J, Esteve-Selma MA, Giménez A. Predation impact on threatened spur-thighed tortoises by golden eagles when main prey is scarce. Sci Rep 2022; 12:17843. [PMID: 36284169 PMCID: PMC9596414 DOI: 10.1038/s41598-022-22288-9] [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: 04/25/2022] [Accepted: 10/12/2022] [Indexed: 01/20/2023] Open
Abstract
A reduction in adult survival in long-living species may compromise population growth rates. The spur-thighed tortoise (Testudo graeca) is a long-lived reptile that is threatened by habitat loss and fragmentation. Golden eagles (Aquila chrysaetos), whose breeding habitats overlap that of tortoises, may predate them by dropping them onto rocks and breaking their carapaces. In SE Spain, the number of golden eagles has increased in the last decades and the abundance of their main prey (i.e., rabbits Oryctolagus cuniculus) has decreased. Our aims were to 1) describe the role of tortoises in golden eagles' diet, and 2) estimate the predation impact of golden eagles on tortoises in eagles' territories and in the regional tortoise population. We collected regurgitated pellets and prey remains under eagle nests and roosts, and obtained information on tortoise abundance and population structure and rabbit abundance. We found that tortoises were an alternative prey to rabbits, so that eagles shifted to the former where the latter were scarce. The average predation rate on tortoises was very low at the two studied scales. However, eagles showed a marked selection for adult female tortoises, which led the tortoise sex ratio to be biased towards males in those eagle territories with higher tortoise predation. Whether this may compromise the spur-thighed tortoise long-term population viability locally deserves further attention.
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Affiliation(s)
- José M. Gil-Sánchez
- grid.4489.10000000121678994Department of Zoology, University of Granada, Avda. de Fuente Nueva, s/n, 18071 Granada, Spain
| | - Roberto C. Rodríguez-Caro
- grid.26811.3c0000 0001 0586 4893Department of Applied Biology, Miguel Hernández University, Avda. de la Universidad, s/n, 03202 Elche, Spain ,grid.4991.50000 0004 1936 8948Department of Zoology, Oxford University, 11a Mansfield Road, Oxford, OX1 3SZ UK ,grid.5268.90000 0001 2168 1800Department of Ecology, University of Alicante, Carr. de San Vicente del Raspeig, s/n, 03690 San Vicente del Raspeig, Alicante, Spain
| | - Marcos Moleón
- grid.4489.10000000121678994Department of Zoology, University of Granada, Avda. de Fuente Nueva, s/n, 18071 Granada, Spain
| | - María C. Martínez-Pastor
- grid.26811.3c0000 0001 0586 4893Department of Applied Biology, Miguel Hernández University, Avda. de la Universidad, s/n, 03202 Elche, Spain
| | - Mario León-Ortega
- Ulula Asociation: Nocturnal Bird Monitoring, C/Herreras y Moreras. 12, 30110 Churra, Murcia, Spain
| | - Sergio Eguía
- MENDIJOB, S.L., c/Rambla, 22, 30120 El Palmar, Murcia, Spain
| | - Eva Graciá
- grid.26811.3c0000 0001 0586 4893Department of Applied Biology, Miguel Hernández University, Avda. de la Universidad, s/n, 03202 Elche, Spain ,grid.26811.3c0000 0001 0586 4893Centro de Investigación e Innovación Agroalimentaria y Agroambiental (CIAGRO-UMH), Miguel Hernández University, Carretera de Beniel Km 3.2, 03312 Orihuela, Spain
| | - Francisco Botella
- grid.26811.3c0000 0001 0586 4893Department of Applied Biology, Miguel Hernández University, Avda. de la Universidad, s/n, 03202 Elche, Spain ,grid.26811.3c0000 0001 0586 4893Centro de Investigación e Innovación Agroalimentaria y Agroambiental (CIAGRO-UMH), Miguel Hernández University, Carretera de Beniel Km 3.2, 03312 Orihuela, Spain
| | - José A. Sánchez-Zapata
- grid.26811.3c0000 0001 0586 4893Department of Applied Biology, Miguel Hernández University, Avda. de la Universidad, s/n, 03202 Elche, Spain ,grid.26811.3c0000 0001 0586 4893Centro de Investigación e Innovación Agroalimentaria y Agroambiental (CIAGRO-UMH), Miguel Hernández University, Carretera de Beniel Km 3.2, 03312 Orihuela, Spain
| | | | - M. A. Esteve-Selma
- grid.10586.3a0000 0001 2287 8496Department of Ecology and Hydrology, University of Murcia, Campus de Espinardo, 30100 Murcia, Spain
| | - A. Giménez
- grid.26811.3c0000 0001 0586 4893Department of Applied Biology, Miguel Hernández University, Avda. de la Universidad, s/n, 03202 Elche, Spain ,grid.26811.3c0000 0001 0586 4893Centro de Investigación e Innovación Agroalimentaria y Agroambiental (CIAGRO-UMH), Miguel Hernández University, Carretera de Beniel Km 3.2, 03312 Orihuela, Spain
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Miranda EBP, Peres CA, Downs CT. Landowner perceptions of livestock predation: implications for persecution of an Amazonian apex predator. Anim Conserv 2021. [DOI: 10.1111/acv.12727] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- E. B. P. Miranda
- Centre for Functional Biodiversity School of Life Sciences University of KwaZulu‐Natal Pietermaritzburg South Africa
| | - C. A. Peres
- School of Environmental Sciences University of East Anglia Norwich UK
- Instituto Juruá Manaus Brazil
| | - C. T. Downs
- Centre for Functional Biodiversity School of Life Sciences University of KwaZulu‐Natal Pietermaritzburg South Africa
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Monclús L, Shore RF, Krone O. Lead contamination in raptors in Europe: A systematic review and meta-analysis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 748:141437. [PMID: 32818895 DOI: 10.1016/j.scitotenv.2020.141437] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/30/2020] [Accepted: 07/31/2020] [Indexed: 06/11/2023]
Abstract
Lead contamination is a widely recognised conservation problem for raptors worldwide. There are a number of studies in individual raptor species but those data have not been systematically evaluated to understand raptor-wide lead exposure and effects at a pan-European scale. To critically assess the extent of this problem, we performed a systematic review compiling all published data on lead in raptors (1983-2019) and, through a meta-analysis, determined if there was evidence for differences in exposure across feeding traits, geographical regions, between hunting and non-hunting periods, and changes over time. We also reviewed the impact of lead on raptors and the likely main source of exposure. We examined 114 studies that were unevenly distributed in terms of time of publication and the countries in which studies were performed. Peer-reviewed articles reported data for 39 raptor species but very few species were widely monitored across Europe. Obligate (vultures) and facultative scavengers (golden eagle, common buzzard and white-tailed sea eagle) accumulated the highest lead concentrations in tissues and generally were the species most at risk of lead poisoning. We found no evidence of a spatial or decadal trend in lead residues, but we demonstrated that high lead blood levels relate to hunting season. Exposure at levels associated with both subclinical and lethal effects is common and lead from rifle bullets and shot is often the likely source of exposure. Overall, our review illustrates the high incidence and ubiquity of lead contamination in raptors in Europe. However, we did not find studies that related exposure to quantitative impacts on European raptor populations nor detailed studies on the impact of mitigation measures. Such information is urgently needed and requires a more harmonised approach to quantifying lead contamination and effects in raptors across Europe.
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Affiliation(s)
- Laura Monclús
- Department of Biology, Norwegian University of Science and Technology, Trondheim 7491, Norway; Department of Animal Health and Anatomy, Autonomous University of Barcelona, Bellaterra 08193, Spain.
| | - Richard F Shore
- U.K. Centre of Ecology and Hydrology, Lancaster Environmental Centre, Lancaster LA1 4AP, UK
| | - Oliver Krone
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin 10315, Germany
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dos Santos Soares VM, de Lucena Soares HK, da Silva Santos S, de Lucena RFP. Local knowledge, use, and conservation of wild birds in the semi-arid region of Paraíba state, northeastern Brazil. JOURNAL OF ETHNOBIOLOGY AND ETHNOMEDICINE 2018; 14:77. [PMID: 30514340 PMCID: PMC6280514 DOI: 10.1186/s13002-018-0276-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 11/21/2018] [Indexed: 05/13/2023]
Abstract
BACKGROUND The use of wild birds, for several purposes, is directly associated with cultural, ecological, and conservation issues. This study aimed to inventory the wild birds known and used in three communities in Paraíba state, northeast Brazil, and to investigate the sociocultural context in which these activities occur. METHODS A total of 179 people (98 women and 81 men) were interviewed. Data were collected through free interviews, using semi-structured forms, and posing questions about the use of local wild birds. The species were identified by direct observation of the birds, analysis of photographic records, and the use of a scientific guide. RESULTS Each species' use value (UV) was calculated in three different ways: UVgeneral, UVcurrent, and UVpotential. These UVs ranged from 0.01 to 1.15 for UVg, 0 to 0.21 for UVc, and 0.01 to 1.02 for UVp. A total of 99 species, 81 genera, and 40 families were recorded and classified into the use categories of food, breeding, and medicinal. Thraupidae (12 species), Columbidae, Accipitridae, and Icteridae (8 species each) were the most diverse families. CONCLUSIONS The use of wild birds is a widespread activity in the studied areas, where many species are used. This demonstrates the need to conduct studies to assess the pressure suffered by these bird species, as well as the need to create public policies that intervene in the use and conservation of wild birds.
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Affiliation(s)
- Vanessa Moura dos Santos Soares
- Laboratório de Etnobiologia e Ciências Ambientais, Departamento de Sistemática e Ecologia, da Universidade Federal da Paraíba, Campus I, João Pessoa, Paraíba CEP: 58.051-900 Brazil
| | - Hyago Keslley de Lucena Soares
- Laboratório de Etnobiologia e Ciências Ambientais, Departamento de Sistemática e Ecologia, da Universidade Federal da Paraíba, Campus I, João Pessoa, Paraíba CEP: 58.051-900 Brazil
| | - Suellen da Silva Santos
- Laboratório de Etnobiologia e Ciências Ambientais, Departamento de Sistemática e Ecologia, da Universidade Federal da Paraíba, Campus I, João Pessoa, Paraíba CEP: 58.051-900 Brazil
| | - Reinaldo Farias Paiva de Lucena
- Laboratório de Etnobiologia e Ciências Ambientais, Departamento de Sistemática e Ecologia, da Universidade Federal da Paraíba, Campus I, João Pessoa, Paraíba CEP: 58.051-900 Brazil
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Gil-Sánchez JM, Molleda S, Sánchez-Zapata JA, Bautista J, Navas I, Godinho R, García-Fernández AJ, Moleón M. From sport hunting to breeding success: Patterns of lead ammunition ingestion and its effects on an endangered raptor. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 613-614:483-491. [PMID: 28918280 DOI: 10.1016/j.scitotenv.2017.09.069] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 09/05/2017] [Accepted: 09/07/2017] [Indexed: 05/27/2023]
Abstract
Lead is highly toxic for wildlife, with pernicious consequences especially in long-lived predators. The causes of lead ammunition ingestion in Bonelli's eagle (Aquila fasciata) and its effects on breeding success were studied in one of the most important populations of this endangered species in Europe. Regurgitated pellets belonging to different pairs from 2004 to 2014 were analyzed, both in the breeding (1363 pellets from 12 territories) and non-breeding (172 pellets from 9 territories) seasons. From these territories, 57 molted feathers to study lead contamination were analyzed, and breeding success was monitored for 41 breeding attempts. The occurrence of lead shots in pellets was detected using X-ray photographs. Pellets were also used to describe eagle diet. Lead shots in pellets were present in 83.3% of the territories. The frequency of occurrence of lead shots in pellets (2.81% in spring and 1.31% in autumn) was primarily related to the consumption of red-legged partridge in the breeding season (when partridges are hunted from blinds using calling lures), and secondarily to rabbit consumption in the non-breeding season (coinciding with the main hunting season). Thus, our results indicate that injured small-game were the main source of lead contamination in the Bonelli's eagle. For the first time for a raptor species, a positive relationship between the frequency of occurrence of lead shots in pellets and lead concentration in eagles' feathers has been documented. Lead concentration in feathers (mean±SD: 816±426μgkg-1, with no sex-related differences) was high for a species that rarely eats carrion or aquatic birds (the main prey-related lead source for raptors). This had negative effects on breeding success, which could jeopardize Bonelli's eagles in other European populations that are sustained by juvenile dispersal from the study population. Our work shows that some game modalities pose a potential threat to endangered raptors.
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Affiliation(s)
- José M Gil-Sánchez
- Department of Zoology, Universidad de Granada, Avda. de Fuentenueva, s/n, 18071 Granada, Spain.
| | - Saray Molleda
- C/de la Puente Astorga 13, 24735, Castrocontrigo, León, Spain
| | - José A Sánchez-Zapata
- Department of Applied Biology, University Miguel Hernández, Avda de la Universidad, s/n, 03202, Elche, Alicante, Spain
| | - Jesús Bautista
- Agencia de Medio Ambiente y Agua de Andalucía, Gerencia de Granada, Calle Minerva, 7, Edificio Zeus III, 18014 Granada, Spain
| | - Isabel Navas
- Area of Toxicology, Department of Health Sciences, IMIB-Arrixaca, University of Murcia, Campus de Espinardo, 30100 Murcia, Spain.
| | - Raquel Godinho
- CIBIO/InBio - Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus de Vairão, 4485-661 Vairão, Portugal.
| | - Antonio J García-Fernández
- Area of Toxicology, Department of Health Sciences, IMIB-Arrixaca, University of Murcia, Campus de Espinardo, 30100 Murcia, Spain.
| | - Marcos Moleón
- Department of Conservation Biology, Doñana Biological Station-CSIC, Avda. Américo Vespucio, s/n, 41092 Sevilla, Spain
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Graciá E, Ortego J, Godoy JA, Pérez-García JM, Blanco G, del Mar Delgado M, Penteriani V, Almodóvar I, Botella F, Sánchez-Zapata JA. Genetic Signatures of Demographic Changes in an Avian Top Predator during the Last Century: Bottlenecks and Expansions of the Eurasian Eagle Owl in the Iberian Peninsula. PLoS One 2015; 10:e0133954. [PMID: 26230922 PMCID: PMC4521928 DOI: 10.1371/journal.pone.0133954] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 07/03/2015] [Indexed: 11/18/2022] Open
Abstract
The study of the demographic history of species can help to understand the negative impact of recent population declines in organisms of conservation concern. Here, we use neutral molecular markers to explore the genetic consequences of the recent population decline and posterior recovery of the Eurasian eagle owl (Bubo bubo) in the Iberian Peninsula. During the last century, the species was the object of extermination programs, suffering direct persecution by hunters until the 70's. Moreover, during the last decades the eagle owl was severely impacted by increased mortality due to electrocution and the decline of its main prey species, the European rabbit (Oryctolagus cuniculus). In recent times, the decrease of direct persecution and the implementation of some conservation schemes have allowed the species' demographic recovery. Yet, it remains unknown to which extent the past population decline and the later expansion have influenced the current species' pattern of genetic diversity. We used eight microsatellite markers to genotype 235 eagle owls from ten Spanish subpopulations and analyse the presence of genetic signatures attributable to the recent population fluctuations experienced by the species. We found moderate levels of differentiation among the studied subpopulations and Bayesian analyses revealed the existence of three genetic clusters that grouped subpopulations from central, south-western and south-eastern Spain. The observed genetic structure could have resulted from recent human-induced population fragmentation, a patchy distribution of prey populations and/or the philopatric behaviour and habitat selection of the species. We detected an old population bottleneck, which occurred approximately 10,000 years ago, and significant signatures of recent demographic expansions. However, we did not find genetic signatures for a recent bottleneck, which may indicate that population declines were not severe enough to leave detectable signals on the species genetic makeup or that such signals have been eroded by the rapid demographic recovery experienced by the species in recent years.
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Affiliation(s)
- Eva Graciá
- Ecology Area, Department of Applied Biology, Miguel Hernández University, Elche, Spain
| | - Joaquín Ortego
- Genetic and Cultural Biodiversity Group, Hunting Resources Research Institute, CSIC-UCLM-JCCM, Ciudad Real, Spain
- Department of Integrative Ecology, Doñana Biological Station, CSIC, Seville, Spain
| | - José Antonio Godoy
- Department of Integrative Ecology, Doñana Biological Station, CSIC, Seville, Spain
| | | | - Guillermo Blanco
- Department of Evolutionary Ecology, National Museum of Natural History, CSIC, Madrid, Spain
| | - María del Mar Delgado
- Department of Biosciences, Metapopulation Research Group, University of Helsinki, Helsinki, Finland
- Research Unit of Biodiversity, UMIB, UO-CSIC-PA, Oviedo University, Campus de Mieres, Mieres, Spain
| | - Vincenzo Penteriani
- Research Unit of Biodiversity, UMIB, UO-CSIC-PA, Oviedo University, Campus de Mieres, Mieres, Spain
- Department of Conservation Biology, Doñana Biological Station, CSIC, Seville, Spain
| | - Irene Almodóvar
- Ecology Area, Department of Applied Biology, Miguel Hernández University, Elche, Spain
| | - Francisco Botella
- Ecology Area, Department of Applied Biology, Miguel Hernández University, Elche, Spain
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Resano-Mayor J, Hernández-Matías A, Real J, Moleón M, Parés F, Inger R, Bearhop S. Multi-scale effects of nestling diet on breeding performance in a terrestrial top predator inferred from stable isotope analysis. PLoS One 2014; 9:e95320. [PMID: 24743233 PMCID: PMC3990674 DOI: 10.1371/journal.pone.0095320] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 03/25/2014] [Indexed: 11/25/2022] Open
Abstract
Inter-individual diet variation within populations is likely to have important ecological and evolutionary implications. The diet-fitness relationships at the individual level and the emerging population processes are, however, poorly understood for most avian predators inhabiting complex terrestrial ecosystems. In this study, we use an isotopic approach to assess the trophic ecology of nestlings in a long-lived raptor, the Bonelli’s eagle Aquila fasciata, and investigate whether nestling dietary breath and main prey consumption can affect the species’ reproductive performance at two spatial scales: territories within populations and populations over a large geographic area. At the territory level, those breeding pairs whose nestlings consumed similar diets to the overall population (i.e. moderate consumption of preferred prey, but complemented by alternative prey categories) or those disproportionally consuming preferred prey were more likely to fledge two chicks. An increase in the diet diversity, however, related negatively with productivity. The age and replacements of breeding pair members had also an influence on productivity, with more fledglings associated to adult pairs with few replacements, as expected in long-lived species. At the population level, mean productivity was higher in those population-years with lower dietary breadth and higher diet similarity among territories, which was related to an overall higher consumption of preferred prey. Thus, we revealed a correspondence in diet-fitness relationships at two spatial scales: territories and populations. We suggest that stable isotope analyses may be a powerful tool to monitor the diet of terrestrial avian predators on large spatio-temporal scales, which could serve to detect potential changes in the availability of those prey on which predators depend for breeding. We encourage ecologists and evolutionary and conservation biologists concerned with the multi-scale fitness consequences of inter-individual variation in resource use to employ similar stable isotope-based approaches, which can be successfully applied to complex ecosystems such as the Mediterranean.
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Affiliation(s)
- Jaime Resano-Mayor
- Equip de Biologia de la Conservació, Departament de Biologia Animal, Universitat de Barcelona, Barcelona, Catalonia, Spain
- * E-mail:
| | - Antonio Hernández-Matías
- Equip de Biologia de la Conservació, Departament de Biologia Animal, Universitat de Barcelona, Barcelona, Catalonia, Spain
| | - Joan Real
- Equip de Biologia de la Conservació, Departament de Biologia Animal, Universitat de Barcelona, Barcelona, Catalonia, Spain
| | - Marcos Moleón
- Departamento de Biología Aplicada, Universidad Miguel Hernández, Orihuela, Alicante, Spain
| | - Francesc Parés
- Equip de Biologia de la Conservació, Departament de Biologia Animal, Universitat de Barcelona, Barcelona, Catalonia, Spain
| | - Richard Inger
- Environment and Sustainability Institute, University of Exeter, Cornwall Campus, Penryn, Cornwall, United Kingdom
| | - Stuart Bearhop
- Centre for Ecology and Conservation, School of Biosciences, University of Exeter, Cornwall Campus, Penryn, Cornwall, United Kingdom
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Lozano J, Virgós E, Cabezas-Díaz S. Monitoring European wildcat Felis silvestris populations using scat surveys in central Spain: are population trends related to wild rabbit dynamics or to landscape features? Zool Stud 2013. [DOI: 10.1186/1810-522x-52-16] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Moleón M, Almaraz P, Sánchez-Zapata JA. Inferring ecological mechanisms from hunting bag data in wildlife management: a reply to Blanco-Aguiar et al. (2012). EUR J WILDLIFE RES 2013. [DOI: 10.1007/s10344-013-0711-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Moleón M, Sebastián-González E, Sánchez-Zapata JA, Real J, Pires MM, Gil-Sánchez JM, Bautista J, Palma L, Bayle P, Guimarães PR, Beja P. Changes in intrapopulation resource use patterns of an endangered raptor in response to a disease-mediated crash in prey abundance. J Anim Ecol 2012; 81:1154-1160. [DOI: 10.1111/j.1365-2656.2012.02006.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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López-López P, Sarà M, Di Vittorio M. Living on the edge: assessing the extinction risk of critically endangered Bonelli's eagle in Italy. PLoS One 2012; 7:e37862. [PMID: 22662239 PMCID: PMC3360590 DOI: 10.1371/journal.pone.0037862] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2012] [Accepted: 04/25/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The population of Bonelli's eagle (Aquila fasciata) has declined drastically throughout its European range due to habitat degradation and unnatural elevated mortality. There are less than 1500 breeding pairs accounted for in Europe, and the species is currently catalogued as Critically Endangered in Italy, where the 22 territories of Sicily, represent nearly 95% of the entire Italian population. However, despite national and European conservation concerns, the species currently lacks a specific conservation plan, and no previous attempts to estimate the risk of extinction have been made. METHODOLOGY/PRINCIPAL FINDINGS We incorporated the most updated demographic information available to assess the extinction risk of endangered Bonelli's eagle in Italy through a Population Viability Analysis. Using perturbation analyses (sensitivity and elasticity), and a combination of demographic data obtained from an assortment of independent methods, we evaluated which demographic parameters have more influence on the population's fate. We also simulated different scenarios to explore the effects of possible management actions. Our results showed that under the current conditions, Bonelli's eagle is expected to become extinct in Italy in less than 50 years. Stand-alone juvenile mortality was the most critical demographic parameter with the strongest influence on population persistence with respect to other demographic parameters. Measures aimed at either decreasing juvenile mortality, adult mortality or decreasing both juvenile and adult mortality resulted in equivalent net positive effects on population persistence (population growth rate λ>1). In contrast, changes aimed at increasing breeding success had limited positive effects on demographic trends. CONCLUSIONS/SIGNIFICANCE Our PVA provides essential information to direct the decision-making process and exposes gaps in our previous knowledge. To ensure the long-term persistence of the species in Italy, measures are urgently needed to decrease both adult mortality due to poaching and juvenile mortality due to nest plundering, the top ranking mortality causes.
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Affiliation(s)
- Pascual López-López
- Vertebrates Zoology Research Group, CIBIO, [corrected] University of Alicante, Alicante, Spain.
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Moleón M, Sánchez-Zapata JA, Gil-Sánchez JM, Ballesteros-Duperón E, Barea-Azcón JM, Virgós E. Predator-prey relationships in a Mediterranean vertebrate system: Bonelli's eagles, rabbits and partridges. Oecologia 2011; 168:679-89. [PMID: 21947548 DOI: 10.1007/s00442-011-2134-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Accepted: 09/02/2011] [Indexed: 12/01/2022]
Abstract
How predators impact on prey population dynamics is still an unsolved issue for most wild predator-prey communities. When considering vertebrates, important concerns constrain a comprehensive understanding of the functioning of predator-prey relationships worldwide; e.g. studies simultaneously quantifying 'functional' and 'numerical responses' (i.e., the 'total response') are rare. The functional, the numerical, and the resulting total response (i.e., how the predator per capita intake, the population of predators and the total of prey eaten by the total predators vary with prey densities) are fundamental as they reveal the predator's ability to regulate prey population dynamics. Here, we used a multi-spatio-temporal scale approach to simultaneously explore the functional and numerical responses of a territorial predator (Bonelli's eagle Hieraaetus fasciatus) to its two main prey species (the rabbit Oryctolagus cuniculus and the red-legged partridge Alectoris rufa) during the breeding period in a Mediterranean system of south Spain. Bonelli's eagle responded functionally, but not numerically, to rabbit/partridge density changes. Type II, non-regulatory, functional responses (typical of specialist predators) offered the best fitting models for both prey. In the absence of a numerical response, Bonelli's eagle role as a regulating factor of rabbit and partridge populations seems to be weak in our study area. Simple (prey density-dependent) functional response models may well describe the short-term variation in a territorial predator's consumption rate in complex ecosystems.
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Affiliation(s)
- Marcos Moleón
- Empresa de Gestión Medioambiental-Consejería de Medio Ambiente, Junta de Andalucía, Granada, Spain.
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