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Strydom Z, Waller LJ, Brown M, Fritz H, Shaw K, Venter JA. Factors that influence Cape fur seal predation on Cape gannets at Lambert's Bay, South Africa. PeerJ 2022; 10:e13416. [PMID: 35722261 PMCID: PMC9202551 DOI: 10.7717/peerj.13416] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 04/19/2022] [Indexed: 01/14/2023] Open
Abstract
Seabird populations experience predation that can impact their breeding density and breeding success. The Cape gannet Morus capensis is endemic to the Benguela upwelling ecosystem and is classified as Endangered by the IUCN. They are affected by several threats, including predation by the Cape fur seal Arctocephalus pusillus pusillus. Many fledglings succumb to predation during their maiden flight across waters around the island. To curb predation, the selective culling of individual predatory seals was implemented in 2014, 2015, and 2018. Our first study objective was to determine if selective culling of Cape fur seals significantly reduced predation probability on Cape gannets. We tested whether predation probability in 2014, 2015, and 2018 was affected by fish biomass, gannet fledgling numbers, and/or the presence/absence of selective culling. Our second objective was to determine what led to fluctuations in Cape fur seal predation on Cape gannet fledglings between 2007 and 2018. We tested whether fish biomass and the amount of Cape gannet fledglings in the water affected predation probability on the fledglings. Results indicated that selective culling reduced predation within years. We found that with both increased fledgling numbers and increased fish biomass, seal predation probability was reduced. This suggests that a sustainable way to promote the conservation of Cape gannets would be to increase food availability for both the Cape fur seals and Cape gannets. Our findings, collectively with the global trend of the declining Cape gannet population and their endemism, provide reasons advocating for the conservation of the food resources of both the Cape fur seal and the Cape gannet in the Benguela system.
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Affiliation(s)
- Zanri Strydom
- Department of Conservation Management, Faculty of Science, Nelson Mandela University, George, South Africa,REHABS International Research Laboratory, CNRS-UCBL-NMU, Nelson Mandela University, George, South Africa
| | - Lauren J. Waller
- Department of Biodiversity and Conservation Biology, University of the Western Cape, Bellville, South Africa,Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), Cape Town, South Africa
| | - Mark Brown
- School of Life Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Hervé Fritz
- Department of Conservation Management, Faculty of Science, Nelson Mandela University, George, South Africa,REHABS International Research Laboratory, CNRS-UCBL-NMU, Nelson Mandela University, George, South Africa
| | - Kevin Shaw
- Scientific Services, CapeNature, Cape Town, South Africa
| | - Jan A. Venter
- Department of Conservation Management, Faculty of Science, Nelson Mandela University, George, South Africa,REHABS International Research Laboratory, CNRS-UCBL-NMU, Nelson Mandela University, George, South Africa
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Valldeperes M, Granados JE, Pérez JM, Castro I, Ráez-Bravo A, Fandos P, López-Olvera JR, Serrano E, Mentaberre G. How sensitive and specific is the visual diagnosis of sarcoptic mange in free-ranging Iberian ibexes? Parasit Vectors 2019; 12:405. [PMID: 31416471 PMCID: PMC6694496 DOI: 10.1186/s13071-019-3665-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 08/09/2019] [Indexed: 12/03/2022] Open
Abstract
Background Sarcoptic mange is a broadly distributed parasitic disease caused by Sarcoptes scabiei that affects wild mammals from all over the world, including the Iberian ibex (Capra pyrenaica). Selective culling of the scabietic individuals is the main management measure for disease control in Iberian ibex populations. Although visual identification of mange-compatible lesions is the reference method to decide the target individual, both false negative and positive cases are common in the wild. The aim of this work is to determine the sensitivity (SE), and the specificity (SP) of selective culling after evaluating 403 ibexes hunted in the Sierra Nevada Nature Space for sarcoptic mange control between 2002 and 2015. Methods A combination of skin scrapings and potassium hidroxide (KOH) skin digestion was used for sarcoptic mange diagnosis. Generalized linear models (GLM) were used to assess the effects of sex, age (juveniles and adults) and period of the year (wet and dry periods) on the SE and SP of the visual diagnosis method. Results The SE obtained for the visual determination of scabietic ibexes was 87.14%, whereas the SP was 60.71%. According to our model selection, SE of the visual diagnosis was explained by the additive effects of age and the period of the year. In fact, SE was lower in juveniles (64.76%) than in adults (94.26%) and during the dry period (73.44%) as compared to the wet period (92.09%). On the other hand, SP was best explained by the GLM including the additive effects of sex and the period of the year. The visual diagnosis of sarcoptic mange resulted less specific in females (22.73%) than in males (74.19%) and during the wet (55.22%) than in the dry period (82.35%). Conclusions Maximizing SE and SP is essential to achieving a high rate of removal of affected individuals from the environment without eliminating potentially resistant individuals. Selective culling must be conservative during the wet period and with females due to the lower SP. Conversely, visual diagnosis of scabietic juveniles and during the dry period has to be improved, due to the lower SE.
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Affiliation(s)
- Marta Valldeperes
- Wildlife Ecology & Health group (WE&H) and Servei d'Ecopatologia de Fauna Salvatge (SEFaS), Departament de Medicina i Cirurgia Animals, Universitat Autònoma de Barcelona (UAB), 08190, Bellaterra, Barcelona, Spain
| | - José Enrique Granados
- Espacio Natural Sierra Nevada, Carretera Antigua de Sierra Nevada, Km 7, Pinos Genil, 18071, Granada, Spain
| | - Jesús María Pérez
- Departamento de Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Campus Las Lagunillas, s.n, 23071, Jaén, Spain
| | - Inmaculada Castro
- Departamento de Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Campus Las Lagunillas, s.n, 23071, Jaén, Spain
| | - Arián Ráez-Bravo
- Wildlife Ecology & Health group (WE&H) and Servei d'Ecopatologia de Fauna Salvatge (SEFaS), Departament de Medicina i Cirurgia Animals, Universitat Autònoma de Barcelona (UAB), 08190, Bellaterra, Barcelona, Spain
| | - Paulino Fandos
- Agencia de Medio Ambiente y Agua de Andalucía, 41092, Isla de la Cartuja,, Sevilla, Spain
| | - Jorge Ramón López-Olvera
- Wildlife Ecology & Health group (WE&H) and Servei d'Ecopatologia de Fauna Salvatge (SEFaS), Departament de Medicina i Cirurgia Animals, Universitat Autònoma de Barcelona (UAB), 08190, Bellaterra, Barcelona, Spain
| | - Emmanuel Serrano
- Wildlife Ecology & Health group (WE&H) and Servei d'Ecopatologia de Fauna Salvatge (SEFaS), Departament de Medicina i Cirurgia Animals, Universitat Autònoma de Barcelona (UAB), 08190, Bellaterra, Barcelona, Spain. .,Dipartimento di Scienze Veterinarie, Universitá di Torino, Grugliasco, Torino, Italy.
| | - Gregorio Mentaberre
- Wildlife Ecology & Health group (WE&H) and Servei d'Ecopatologia de Fauna Salvatge (SEFaS), Departament de Medicina i Cirurgia Animals, Universitat Autònoma de Barcelona (UAB), 08190, Bellaterra, Barcelona, Spain.,Departament de Ciència Animal, Escola Tècnica Superior d'Enginyeria Agraria (ETSEA), Universitat de Lleida (UdL), 25098, Lleida, Spain
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Che'Amat A, Armenteros JA, González-Barrio D, Lima JF, Díez-Delgado I, Barasona JA, Romero B, Lyashchenko KP, Ortiz JA, Gortázar C. Is targeted removal a suitable means for tuberculosis control in wild boar? Prev Vet Med 2016; 135:132-135. [PMID: 27843020 DOI: 10.1016/j.prevetmed.2016.11.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 10/28/2016] [Accepted: 11/03/2016] [Indexed: 11/16/2022]
Abstract
We assessed the suitability of targeted removal as a means for tuberculosis (TB) control on an intensely managed Eurasian wild boar (Sus scrofa) hunting estate. The 60km2 large study area included one capture (treatment) site, one control site, and one release site. Each site was fenced. In the summers of 2012, 2013 and 2014, 929 wild boar were live-captured on the treatment site. All wild boar were micro-chipped and tested using an animal side lateral flow test immediately after capture in order to detect antibodies to the Mycobacterium tuberculosis complex (MTC). The wild boar were released according to their TB status: Seropositive individuals onto the release site (hunted after summer), and seronegative individuals back onto the treatment site. The annual summer seroprevalence of antibodies to the MTC declined significantly in live-captured wild boar piglets from the treatment site, from 44% in 2012 to 27% in 2013 (a reduction of 39%). However, no significant further reduction was recorded in 2014, during the third capture season. Fall-winter MTC infection prevalence was calculated on the basis of the culture results obtained for hunter-harvested wild boar. No significant changes between hunting seasons were recorded on either the treatment site or the control site, and prevalence trends over time were similar on both sites. The fall-winter MTC infection prevalence on the release site increased significantly from 40% in 2011-2012 to 64% in 2012-2013 and 2013-2014 (60% increase). Recaptures indicated a persistently high infection pressure. This experiment, the first attempt to control TB in wild boar through targeted removal, failed to reduce TB prevalence when compared to the control site. However, it generated valuable knowledge on infection pressure and on the consequences of translocating TB-infected wild boar.
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Affiliation(s)
- A Che'Amat
- SaBio Instituto de Investigación en Recursos Cinegéticos IREC (CSIC-UCLM-JCCM), Ronda de Toledo s.n. 13005 Ciudad Real, Spain; Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - J A Armenteros
- SaBio Instituto de Investigación en Recursos Cinegéticos IREC (CSIC-UCLM-JCCM), Ronda de Toledo s.n. 13005 Ciudad Real, Spain
| | - D González-Barrio
- SaBio Instituto de Investigación en Recursos Cinegéticos IREC (CSIC-UCLM-JCCM), Ronda de Toledo s.n. 13005 Ciudad Real, Spain
| | - J F Lima
- SaBio Instituto de Investigación en Recursos Cinegéticos IREC (CSIC-UCLM-JCCM), Ronda de Toledo s.n. 13005 Ciudad Real, Spain; Sabiotec, Camino de Moledores s.n., Campus Universitario, 13005 Ciudad Real, Spain
| | - I Díez-Delgado
- SaBio Instituto de Investigación en Recursos Cinegéticos IREC (CSIC-UCLM-JCCM), Ronda de Toledo s.n. 13005 Ciudad Real, Spain; Departamento de Sanidad Animal, Universidad Complutense, 28040 Madrid, Spain
| | - J A Barasona
- SaBio Instituto de Investigación en Recursos Cinegéticos IREC (CSIC-UCLM-JCCM), Ronda de Toledo s.n. 13005 Ciudad Real, Spain
| | - B Romero
- Centro de Vigilancia Sanitaria Veterinaria VISAVET, Avenida de Puerta de Hierro, s.n. 28040 Madrid, Spain
| | | | - J A Ortiz
- Medianilla Red Deer Genetics, Benalup, Cádiz, Spain
| | - C Gortázar
- SaBio Instituto de Investigación en Recursos Cinegéticos IREC (CSIC-UCLM-JCCM), Ronda de Toledo s.n. 13005 Ciudad Real, Spain.
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