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Malchow AK, Fandos G, Kormann UG, Grüebler MU, Kéry M, Hartig F, Zurell D. Fitting individual-based models of spatial population dynamics to long-term monitoring data. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2024; 34:e2966. [PMID: 38629509 DOI: 10.1002/eap.2966] [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: 10/04/2023] [Accepted: 12/20/2023] [Indexed: 06/04/2024]
Abstract
Generating spatial predictions of species distribution is a central task for research and policy. Currently, correlative species distribution models (cSDMs) are among the most widely used tools for this purpose. However, a fundamental assumption of cSDMs, that species distributions are in equilibrium with their environment, is rarely fulfilled in real data and limits the applicability of cSDMs for dynamic projections. Process-based, dynamic SDMs (dSDMs) promise to overcome these limitations as they explicitly represent transient dynamics and enhance spatiotemporal transferability. Software tools for implementing dSDMs are becoming increasingly available, but their parameter estimation can be complex. Here, we test the feasibility of calibrating and validating a dSDM using long-term monitoring data of Swiss red kites (Milvus milvus). This population has shown strong increases in abundance and a progressive range expansion over the last decades, indicating a nonequilibrium situation. We construct an individual-based model using the RangeShiftR modeling platform and use Bayesian inference for model calibration. This allows the integration of heterogeneous data sources, such as parameter estimates from published literature and observational data from monitoring schemes, with a coherent assessment of parameter uncertainty. Our monitoring data encompass counts of breeding pairs at 267 sites across Switzerland over 22 years. We validate our model using a spatial-block cross-validation scheme and assess predictive performance with a rank-correlation coefficient. Our model showed very good predictive accuracy of spatial projections and represented well the observed population dynamics over the last two decades. Results suggest that reproductive success was a key factor driving the observed range expansion. According to our model, the Swiss red kite population fills large parts of its current range but has potential for further increases in density. We demonstrate the practicality of data integration and validation for dSDMs using RangeShiftR. This approach can improve predictive performance compared to cSDMs. The workflow presented here can be adopted for any population for which some prior knowledge on demographic and dispersal parameters as well as spatiotemporal observations of abundance or presence/absence are available. The fitted model provides improved quantitative insights into the ecology of a species, which can greatly aid conservation and management efforts.
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Affiliation(s)
| | - Guillermo Fandos
- Institute for Biochemistry and Biology, University of Potsdam, Potsdam, Germany
- Department of Biodiversity, Ecology and Evolution, Complutense University of Madrid, Madrid, Spain
| | - Urs G Kormann
- Swiss Ornithological Institute, Sempach, Switzerland
| | | | - Marc Kéry
- Swiss Ornithological Institute, Sempach, Switzerland
| | - Florian Hartig
- Theoretical Ecology, Faculty of Biology and Pre-Clinical Medicine, University of Regensburg, Regensburg, Germany
| | - Damaris Zurell
- Institute for Biochemistry and Biology, University of Potsdam, Potsdam, Germany
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Navarro I, Farfán MÁ, Gil JA, Muñoz AR. Survival Estimation Using Multistate Cormack-Jolly-Seber Models-The Case of the Bearded Vulture Gypaetus barbatus in Spain. Animals (Basel) 2024; 14:403. [PMID: 38338045 PMCID: PMC10854860 DOI: 10.3390/ani14030403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Revised: 01/17/2024] [Accepted: 01/24/2024] [Indexed: 02/12/2024] Open
Abstract
The bearded vulture (Gypaetus barbatus) is an endangered species with a specialist osteophagous (bone) diet. We estimated the survival and productivity of this vulture in the Aragonese Pyrenees, where the main population of the species in Europe is found. We used a database covering a period of 33 years (1987-2020). To estimate the probability of survival, we used Cormack-Jolly-Seber models with a Bayesian approach. Our models estimated a survival rate of 0.90 ± 0.08 in juveniles, 0.95 ± 0.04 in subadults and 0.92 ± 0.05 in adults. The survival probability increased over the study period in adults and subadults but not in juveniles. By contrast, productivity decreased over the same period. Our study provides updated information on the status of two demographic parameters of great importance to the species and allows us to identify the most vulnerable age classes and to plan conservation actions to improve the situation of the species in a territory that is a donor of specimens for reintroduction projects. The estimated survival values suggest that more caution should be exercised when planning these feeding points according to the use the species makes of them.
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Affiliation(s)
- Inmaculada Navarro
- Departament of Animal Biology, Faculty of Science, Universidad de Málaga, Campus de Teatinos, 29071 Malaga, Spain; (M.Á.F.); (A.R.M.)
| | - Miguel Ángel Farfán
- Departament of Animal Biology, Faculty of Science, Universidad de Málaga, Campus de Teatinos, 29071 Malaga, Spain; (M.Á.F.); (A.R.M.)
| | - Juan Antonio Gil
- Fundación para la Conservación del Quebrantahuesos, 50001 Zaragoza, Spain;
| | - Antonio Román Muñoz
- Departament of Animal Biology, Faculty of Science, Universidad de Málaga, Campus de Teatinos, 29071 Malaga, Spain; (M.Á.F.); (A.R.M.)
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Murgatroyd M, Tate G, Amar A. Using GPS tracking to monitor the breeding performance of a low-density raptor improves accuracy, and reduces long-term financial and carbon costs. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221447. [PMID: 37650057 PMCID: PMC10465196 DOI: 10.1098/rsos.221447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 08/02/2023] [Indexed: 09/01/2023]
Abstract
Traditionally, demographic monitoring of birds has been undertaken by intensive monitoring of nesting sites. However, this is challenging for low-density species, whereby the effort and costs involved in locating and monitoring remote sites can be prohibitive or even bias research findings. We show that Global Positioning System (GPS) tracking can overcome these challenges for a low-density raptor. Field monitoring of martial eagles Polemaetus bellicosus from 2013 to 2021 showed consistently poor breeding performance, with a mean productivity of 0.22 (±0.04) fledged young/pair/year. Using GPS tracking data to infer breeding performance gave a significantly higher productivity of 0.46 (±0.10) fledged young/pair/year. Breeding rate and success were also underestimated by field monitoring. These differences were likely due to logistical constraints of field monitoring, particularly relating to finding alternative nests. Comparing costs between approaches, we estimated that GPS monitoring was financially cheaper than field monitoring per sample after 10 years. Carbon costs per sample were lower for GPS-based approaches than field monitoring from the second year, and over a 10-year period GPS monitoring produced considerable savings (200% less carbon). We recommend that despite high initial costs, for long-term demographic monitoring of low-density species, or where logistical constraints make traditional field monitoring inaccurate, remote monitoring options should be considered.
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Affiliation(s)
- M. Murgatroyd
- FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, Cape Town 7701, South Africa
- HawkWatch International, 2240 South 900 East, Salt Lake City, UT 84106, USA
- The Endangered Wildlife Trust, 27 and 28 Austin Road, Glen Austin, Midrand, Johannesburg 1685, South Africa
| | - G. Tate
- FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, Cape Town 7701, South Africa
- The Endangered Wildlife Trust, 27 and 28 Austin Road, Glen Austin, Midrand, Johannesburg 1685, South Africa
| | - A. Amar
- FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, Cape Town 7701, South Africa
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4
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Keevil MG, Noble N, Boyle SP, Lesbarrères D, Brooks RJ, Litzgus JD. Lost reproductive value reveals a high burden of juvenile road mortality in a long-lived species. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2023; 33:e2789. [PMID: 36482023 DOI: 10.1002/eap.2789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 07/23/2022] [Accepted: 08/25/2022] [Indexed: 06/17/2023]
Abstract
Adult mortality is often the most sensitive vital rate affecting at-risk wildlife populations. Therefore, road ecology studies often focus on adult mortality despite the possibility for roads to be hazardous to juvenile individuals during natal dispersal. Failure to quantify concurrent variation in mortality risk and population sensitivity across demographic states can mislead the efforts to understand and mitigate the effects of population threats. To compare relative population impacts from road mortality among demographic classes, we weighted mortality observations by applying reproductive value analysis to quantify expected stage-specific contributions to population growth. We demonstrate this approach for snapping turtles (Chelydra serpentina) observed on roads at two focal sites in Ontario, Canada, where we collected data for both live and dead individuals observed on roads. We estimated reproductive values using stage-classified matrix models to compare relative population-level impacts of adult and juvenile mortality. Reproductive value analysis is a tractable approach to assessing demographically variable effects for applications covering large spatial scales, nondiscrete populations, or where abundance data are lacking. For one site with long-term life-history data, we compared demographic frequency on roads to expected general population frequencies predicted by the matrix model. Our application of reproductive value is sex specific but, as juvenile snapping turtles lack external secondary sex characters, we estimated the sex ratio of road-crossing juveniles after dissecting and sexing carcasses collected on roads at five sites across central Ontario, Canada. Juveniles were more abundant on roads than expected, suggesting a substantial dispersal contribution, and the road-killed juvenile sex ratio approached 1:1. A higher proportion of juveniles were also found dead compared with adults, and cumulative juvenile mortality had similar population-level importance as adult mortality. This suggests that the impact of roads needs to be considered across all life stages, even in wildlife species with slow life histories, such as snapping turtles, that are particularly sensitive to adult mortality.
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Affiliation(s)
- Matthew G Keevil
- School of Natural Sciences, Laurentian University, Sudbury, Ontario, Canada
| | - Natasha Noble
- School of Natural Sciences, Laurentian University, Sudbury, Ontario, Canada
| | - Sean P Boyle
- School of Natural Sciences, Laurentian University, Sudbury, Ontario, Canada
| | - David Lesbarrères
- School of Natural Sciences, Laurentian University, Sudbury, Ontario, Canada
| | - Ronald J Brooks
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
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Sergio F, Tavecchia G, Blas J, Tanferna A, Hiraldo F, Korpimaki E, Beissinger SR. Hardship at birth alters the impact of climate change on a long-lived predator. Nat Commun 2022; 13:5517. [PMID: 36167683 PMCID: PMC9515099 DOI: 10.1038/s41467-022-33011-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 08/29/2022] [Indexed: 11/15/2022] Open
Abstract
Climate change is increasing the frequency of extreme events, such as droughts or hurricanes, with substantial impacts on human and wildlife communities. Extreme events can affect individuals through two pathways: by altering the fitness of adults encountering a current extreme, and by affecting the development of individuals born during a natal extreme, a largely overlooked process. Here, we show that the impact of natal drought on an avian predator overrode the effect of current drought for decades, so that individuals born during drought were disadvantaged throughout life. Incorporation of natal effects caused a 40% decline in forecasted population size and a 21% shortening of time to extinction. These results imply that climate change may erode populations more quickly and severely than currently appreciated, suggesting the urgency to incorporate “penalties” for natal legacies in the analytical toolkit of impact forecasts. Similar double impacts may apply to other drivers of global change. The long-term effects of extreme climate events in early life are largely overlooked in forecasts of climate change impacts. Here, the authors show that raptorial red kites born during drought are disadvantaged throughout life, and including this climate legacy leads to substantial decreases in forecasted population size and time to extinction.
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Affiliation(s)
- Fabrizio Sergio
- Department of Conservation Biology, Estación Biológica de Doñana - CSIC, 41092, Seville, Spain.
| | - Giacomo Tavecchia
- Population Ecology Group, Institute for Mediterranean Studies (IMEDEA), CSIC-UIB, 07190, Esporles, Spain
| | - Julio Blas
- Department of Conservation Biology, Estación Biológica de Doñana - CSIC, 41092, Seville, Spain
| | - Alessandro Tanferna
- Department of Conservation Biology, Estación Biológica de Doñana - CSIC, 41092, Seville, Spain
| | - Fernando Hiraldo
- Department of Conservation Biology, Estación Biológica de Doñana - CSIC, 41092, Seville, Spain
| | - Erkki Korpimaki
- Section of Ecology, Department of Biology, University of Turku, FI-20014, Turku, Finland
| | - Steven R Beissinger
- Department of Environmental Science, Policy & Management, University of California, Berkeley, 94720, CA, USA.,Museum of Vertebrate Zoology, University of California, Berkeley, 94720, CA, USA
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Mattsson BJ, Mateo-Tomás P, Aebischer A, Rösner S, Kunz F, Schöll EM, Åkesson S, De Rosa D, Orr-Ewing D, Bodega DDL, Ferrer M, Gelpke C, Katzenberger J, Maciorowski G, Mammen U, Kolbe M, Millon A, Mionnet A, Puente JDL, Raab R, Vyhnal S, Ceccolini G, Godino A, Crespo-Luengo G, Sanchez-Agudo JA, Martínez J, Iglesias-Lebrija JJ, Ginés E, Cortés M, Deán JI, Calmaestra RG, Dostál M, Steinborn E, Viñuela J. Enhancing monitoring and transboundary collaboration for conserving migratory species under global change: The priority case of the red kite. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 317:115345. [PMID: 35642814 DOI: 10.1016/j.jenvman.2022.115345] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 05/16/2022] [Accepted: 05/16/2022] [Indexed: 06/15/2023]
Abstract
Calls for urgent action to conserve biodiversity under global change are increasing, and conservation of migratory species in this context poses special challenges. In the last two decades the Convention on the Conservation of Migratory Species of Wild Animals (CMS) has provided a framework for several subsidiary instruments including action plans for migratory bird species, but the effectiveness and transferability of these plans remain unclear. Such laws and policies have been credited with positive outcomes for the conservation of migratory species, but the lack of international coordination and on-ground implementation pose major challenges. While research on migratory populations has received growing attention, considerably less emphasis has been given to integrating ecological information throughout the annual cycle for examining strategies to conserve migratory species at multiple scales in the face of global change. We fill this gap through a case study examining the ecological status and conservation of a migratory raptor and facultative scavenger, the red kite (Milvus milvus), whose current breeding range is limited to Europe and is associated with agricultural landscapes and restricted to the temperate zone. Based on our review, conservation actions have been successful at recovering red kite populations within certain regions. Populations however remain depleted along the southern-most edge of the geographic range where many migratory red kites from northern strongholds overwinter. This led us to a forward-looking and integrated strategy that emphasizes international coordination involving researchers and conservation practitioners to enhance the science-policy-action interface. We identify and explore key issues for conserving the red kite under global change, including enhancing conservation actions within and outside protected areas, recovering depleted populations, accounting for climate change, and transboundary coordination in adaptive conservation and management actions. The integrated conservation strategy is sufficiently general such that it can be adapted to inform conservation of other highly mobile species subject to global change.
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Affiliation(s)
- Brady J Mattsson
- Institute of Wildlife Biology and Game Management, Department of Integrative Biology and Biodiversity Research, University of Natural Resources and Life Sciences Vienna, Austria.
| | - Patricia Mateo-Tomás
- Biodiversity Research Institute (University of Oviedo-CSIC-Principality of Asturias), Mieres, Spain, and Center for Functional Ecology (CFE), Coimbra University, Portugal
| | | | - Sascha Rösner
- Faculty of Biology, Department of Conservation Ecology, Philipps-University of Marburg, Marburg, Germany
| | - Florian Kunz
- Institute of Wildlife Biology and Game Management, Department of Integrative Biology and Biodiversity Research, University of Natural Resources and Life Sciences Vienna, Austria
| | - Eva M Schöll
- Institute of Wildlife Biology and Game Management, Department of Integrative Biology and Biodiversity Research, University of Natural Resources and Life Sciences Vienna, Austria
| | | | - Davide De Rosa
- ARDEA- Associazione per La Ricerca, La Divulgazione e L'Educazione Ambientale, Via Ventilabro 6, 80126, Naples, Italy
| | - Duncan Orr-Ewing
- Centre for Conservation Science, Royal Society for the Protection of Birds, Scotland, UK
| | | | - Miguel Ferrer
- Doñana Biological Station, Spanish National Research Council (CSIC), Seville, Spain
| | | | | | - Grzegorz Maciorowski
- Department of Game Management and Forest Protection, Poznań University of Life Sciences, Poznań, Poland
| | - Ubbo Mammen
- ÖKOTOP Halle, MEROS (Monitoring of European Raptors and Owls), Halle, Germany
| | - Martin Kolbe
- Rotmilanzentrum am Museum Heineanum, Halberstadt, Germany
| | - Alexandre Millon
- Aix-Marseille Univ, CNRS-IRD-Avignon Univ, Institut Méditerranean Biodiversité Ecologie Marine et Continentale (IMBE), Technopôle Arbois-Méditerranée, Aix-en-Provence, France
| | - Aymeric Mionnet
- Ligue pour La Protection des Oiseaux (LPO), Champagne-Ardenne, Outines, France
| | | | - Rainer Raab
- Technical Office for Biology, Deutsch-Wagram, Austria
| | | | | | | | - Gabriela Crespo-Luengo
- Grupo de Investigación en Biodiversidad, Diversidad Humana y Biología Animal, Universidad de Salamanca, Spain
| | - Jose Angel Sanchez-Agudo
- Grupo de Investigación en Biodiversidad, Diversidad Humana y Biología Animal, Universidad de Salamanca, Spain
| | - Juan Martínez
- GREFA (Grupo de Rehabilitación de La Fauna Autóctona y su Hábitat), Madrid, Spain
| | | | - Ester Ginés
- Servicio Provincial de Agricultura, Ganadería y Medio Ambiente, Gobierno de Aragón, Zaragoza, Spain
| | - Maria Cortés
- Centro de Recuperación de Fauna Silvestre de La Alfranca, Gobierno de Aragón, Pastriz (Zaragoza), Spain
| | - Juan I Deán
- Sociedad de Ciencias Naturales Gorosti, Pamplona, Spain
| | - Ricardo Gómez Calmaestra
- Subdirección General de Biodiversidad Terrestre y Marina, Dirección General de Biodiversidad, Bosques y Desertificación, Ministerio para La Transición Ecológica y El Reto Demográfico, Madrid, Spain
| | - Marek Dostál
- University of Veterinary Sciences Brno, Brno, Czech Republic
| | - Eike Steinborn
- Rotmilanzentrum am Museum Heineanum, Halberstadt, Germany
| | - Javier Viñuela
- Instituto de Investigación en Recursos Cinegéticos (IREC; CSIC-UCLM-JCCM). Ronda de Toledo 12, 13071, Ciudad Real, Spain
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Oppel S, Clark BL, Risi MM, Horswill C, Converse SJ, Jones CW, Osborne AM, Stevens K, Perold V, Bond AL, Wanless RM, Cuthbert R, Cooper J, Ryan PG. Cryptic population decrease due to invasive species predation in a long‐lived seabird supports need for eradication. J Appl Ecol 2022. [DOI: 10.1111/1365-2664.14218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Steffen Oppel
- RSPB Centre for Conservation Science Royal Society for the Protection of Birds, The David Attenborough Building Cambridge UK
| | - Bethany L. Clark
- BirdLife International The David Attenborough Building Cambridge UK
| | - Michelle M. Risi
- RSPB Centre for Conservation Science Royal Society for the Protection of Birds, The David Attenborough Building Cambridge UK
| | - Catharine Horswill
- ZSL Institute of Zoology, Regent's Park London UK
- Centre for Biodiversity and Environmental Research, Department of Genetics, Evolution and Environment University College London London UK
- Department of Zoology University of Cambridge Cambridge UK
| | - Sarah J. Converse
- U.S. Geological Survey, Washington Cooperative Fish and Wildlife Research Unit, School of Environmental and Forest Sciences & School of Aquatic and Fishery Sciences University of Washington Seattle WA USA
| | - Christopher W. Jones
- RSPB Centre for Conservation Science Royal Society for the Protection of Birds, The David Attenborough Building Cambridge UK
| | - Alexis M. Osborne
- RSPB Centre for Conservation Science Royal Society for the Protection of Birds, The David Attenborough Building Cambridge UK
| | - Kim Stevens
- RSPB Centre for Conservation Science Royal Society for the Protection of Birds, The David Attenborough Building Cambridge UK
| | - Vonica Perold
- RSPB Centre for Conservation Science Royal Society for the Protection of Birds, The David Attenborough Building Cambridge UK
| | - Alexander L. Bond
- RSPB Centre for Conservation Science Royal Society for the Protection of Birds, The David Attenborough Building Cambridge UK
- Bird Group, Department of Life Sciences The Natural History Museum Tring Hertfordshire UK
| | - Ross M. Wanless
- FitzPatrick Institute of African Ornithology University of Cape Town Rondebosch South Africa
| | - Richard Cuthbert
- RSPB Centre for Conservation Science Royal Society for the Protection of Birds, The David Attenborough Building Cambridge UK
- World Land Trust Halesworth UK
| | - John Cooper
- FitzPatrick Institute of African Ornithology University of Cape Town Rondebosch South Africa
| | - Peter G. Ryan
- FitzPatrick Institute of African Ornithology University of Cape Town Rondebosch South Africa
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Sergio F, Blas J, Tanferna A, Hiraldo F. Protected areas enter a new era of uncertain challenges: extinction of a non‐exigent falcon in Doñana National Park. Anim Conserv 2021. [DOI: 10.1111/acv.12752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- F. Sergio
- Department of Conservation Biology Estación Biológica de Doñana – CSIC Seville Spain
| | - J. Blas
- Department of Conservation Biology Estación Biológica de Doñana – CSIC Seville Spain
| | - A. Tanferna
- Department of Conservation Biology Estación Biológica de Doñana – CSIC Seville Spain
| | - F. Hiraldo
- Department of Conservation Biology Estación Biológica de Doñana – CSIC Seville Spain
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Warret Rodrigues C, Angin B, Besnard A. Favoring recruitment as a conservation strategy to improve the resilience of long-lived reptile populations: Insights from a population viability analysis. Ecol Evol 2021; 11:13068-13080. [PMID: 34646453 PMCID: PMC8495825 DOI: 10.1002/ece3.8021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 07/09/2021] [Accepted: 07/22/2021] [Indexed: 12/02/2022] Open
Abstract
In long-lived species, although adult survival typically has the highest elasticity, temporal variations in less canalized demographic parameters are the main drivers of population dynamics. Targeting recruitment rates may thus be the most effective strategy to manage these species. We analyzed 1,136 capture-recapture histories collected over 9 years in an isolated population of the critically endangered Lesser Antillean iguana, using a robust design Pradel model to estimate adult survival and recruitment rates. From an adult population size estimated at 928 in 2013, we found a yearly decline of 4% over the 8-year period. As expected under the canalization hypothesis for a long-lived species, adult survival was high and constant, with little possibility for improvement, whereas the recruitment rate varied over time and likely drove the observed population decline. We then used a prospective perturbation analysis to explore whether managing the species' immature cohorts would at least slow the population decline. The prospective perturbation analysis suggested that a significant and sustained conservation effort would be needed to achieve a recruitment rate high enough to slow the population decline. We posit that the high recruitment rate achieved in 2014-likely due to the maintenance in 2012 of the main nesting sites used by this population-would be sufficient to slow this population's decline if it was sustained each year. Based on the results of diverse pilot studies we conducted, we identified the most likely threats targeting the eggs and immature cohorts, stressing the need to improve reproductive success and survival of immature iguanas. The threats we identified are also involved in the decline of several reptile species, and species from other taxa such as ground-nesting birds. These findings on a little-studied taxon provide further evidence that focusing on the immature life stages of long-lived species can be key to their conservation.
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Affiliation(s)
- Chloé Warret Rodrigues
- Office National de la Chasse et de la Faune SauvageCellule Technique des Antilles françaisesTrois‐îletsFrance
- Department of Biological SciencesUniversity of ManitobaWinnipegCanada
| | | | - Aurélien Besnard
- CEFEUniv MontpellierCNRSEPHE‐PSL UniversityIRDUniv Paul Valéry Montpellier 3MontpellierFrance
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