Fils RSS disponibles sur ce site
Les articles de Clémence Deschamp
de Pierre Defos du Rau, Ugoline Godeau, Nicolas Carenton, Jaime Dias, Abakar Saleh Wachoum, BERTRAND Trolliet, Khalil Baddour, Abdramane Chaibo, Guillaume P. Morin, Bruno Portier, et al.
In Proceedings of the National Academy of Sciences, 123(27) (July, 2026), e2603538123
En ligne : www.pnas.org[...]
Lake Chad is both one of the largest transboundary wetlands in Africa and a major biodiversity hotspot. As such, Lake Chad would require sound and long-term biodiversity monitoring, but it is also a war zone. Using several mitigation measures, we succeeded in surveying a major part of it in 2022 to estimate the abundance of wildlife. This study marked the first comprehensive population estimates for some species. Compared to previous total count approaches, we introduced an aerial distance sampling methodology to improve survey safety, repeatability, estimate uncertainty, and reduce detection bias. Due to strong security concerns, a portion of the lake was inaccessible. To overcome this limitation and estimate temporal trends, density surface modeling was applied to estimate species abundance over the entire lake. Locations of conflict events emerged as sites of higher densities for several species, suggesting a “refuge effect,” a rare positive outcome of conflict zones on wildlife. Indeed, we also noted the persistence of endangered large mammal populations, possibly due to reduced anthropogenic pressure from displaced communities. Results indicated that Lake Chad hosts approximately 2.48 million waterbirds, to our knowledge the most important known wetland bird concentration in Africa. Updated population estimates revealed that some species may have experienced positive trends. However, a few species, including transcontinental ones, showed signs of reduced abundance. The study urges actions to protect this ecosystem of major importance for global biodiversity, recommending the establishment of a protected area and World Heritage status for Lake Chad.Bird monitoring in Africa: present state and future prospects
de Philip W. Atkinson, Ngone Diop, Robert A. Robinson, Res Altwegg, Arjun Amar, Ian Barber, André J. Botha, Graeme Buchanan, Achilles Byaruhanga, Adams Chaskda, et al.
In Bird Conservation International, 36 (January, 2026), e12
En ligne : www.cambridge.org[...]
Biodiversity monitoring is essential to inform the state of wildlife populations, and the impacts of environmental change, conservation intervention, and sustainable development policies and actions. We review the current state of bird monitoring across Africa using public questionnaires and semi-structured interviews. We received 87 questionnaire responses from 46 (of 54) countries and, additionally, 24 in-depth interviews were carried out. Multiple data collection methods were reported with total counts of individuals being most frequent, but all-species surveys, essential for quantifying ecosystem health, were restricted to bird atlases and Common Bird Monitoring (CBM) projects in Kenya, Uganda, and Botswana. Data collection relied largely on volunteers, but their motivation, recruitment, training, and retention is a continuing challenge. The most sustainable programmes were driven by clear policy objectives (e.g. waterbird monitoring under the Ramsar Convention or the Convention on the Conservation of Migratory Species), monitoring of individual groups (e.g. raptors, vultures, bustards), specific threatened species, and where clear national priorities had been set within government agencies. Use of monitoring data by governments in country biodiversity reports or National Biodiversity Species Action Plans (NBSAPs) varied widely and, for many countries, simply did not exist. A lack of skilled analysts and a comprehensive approach to data curation and ownership were identified as major limitations. A more strategic approach to funding and monitoring is needed, whereby smaller funders collaborate to reduce costs associated with applying for small amounts of money, and bird (and biodiversity) monitoring is explicitly integrated with sustainable development goals to exploit broader funding streams.
//
La surveillance de la biodiversité est essentielle pour informer sur l’état des populations sauvages et ainsi que sur les impacts des changements environnementaux, des mesures de conservation et des politiques et actions de développement durable. Nous avons examiné l’état actuel de la surveillance des oiseaux en Afrique à l’aide de questionnaires publics et d’entretiens semi-structurés. Nous avons reçu 87 réponses provenant de 46 pays (sur 54) et, en complément, 24 entretiens approfondis ont été menés. Plusieurs méthodes de collecte de données ont été rapportées, les dénombrements totaux d’individus étant les plus fréquents, cependant les inventaires couvrant toutes les espèces, essentielles pour quantifier la santé des écosystèmes étaient limités aux atlas ornithologiques et aux programmes de Suivi des Oiseaux Communs (CBM) au Kenya, en Ouganda et au Botswana. La collecte des données reposait largement sur des bénévoles, mais leur motivation, leur recrutement, leur formation et leur fidélisation restent des défis permanents. Les programmes les plus durables étaient ceux motivés par des objectifs politiques clairs (par exemple le suivi des oiseaux d’eau dans le cadre de la Convention de Ramsar ou de la Convention sur la Conservation des Espèces Migratrices), le suivi de groupes particuliers (par exemple les rapaces, vautours, outardes), des espèces menacées spécifiques, ainsi que ceux où des priorités nationales clairement définies avaient été établies au sein des agences gouvernementales. L’utilisation de données librement accessibles par les gouvernements dans les rapports nationaux sur la biodiversité ou les Plans d’Action Nationaux pour la Biodiversité (NBSAPs) variait considérablement et, pour de nombreux pays, était inexistante. Le manque d’analystes qualifiés et l’absence d’approche cohérente en matière de gestion et de propriété des données ont été identifiés comme des obstacles majeurs. Une approche plus stratégique du financement et du suivi est nécessaire, dans laquelle les petits bailleurs collaborent pour réduire les coûts liés aux demandes de financements de faible montant, et où le suivi des oiseaux (et de la biodiversité) est explicitement intégré aux objectifs de développement durable afin d’exploiter des sources de financement plus larges.
de Nicolas Carenton, Pierre Defos du Rau, Abakar Saleh Wachoum, Delphine Ducros, Marie Suet, Clemence Deschamps, Maxime Rotoudjimbaye Betoloum, Julien Birard, M' Baïti Narcisse Djimasngar, Yves Kayser, et al.
In Journal of Applied Ecology, (Online version) (July, 2024)
En ligne : onlinelibrary.wiley.com[...]
Sustainable harvest of wildlife is a major food security and conservation issue. In Africa, where wildlife is harvested mainly for subsistence, this remains a challenge. In this study, using waterbirds as model for natural resources, we assessed the sustainability of harvest through fishing bycatch on Lake Fitri (Chad). We estimated the abundance of 24 target taxa through aerial distance sampling over four consecutive years (2018–2021) and in parallel estimated the number of birds harvested through interviews of a sample of 105 out of approximately 5500 fishermen. By modelling their potential excess growth, we found a high risk of overexploitation for four species, including the world-threatened Black Crowned Crane Balearica pavonina, likely due to an influx of fishermen to Lake Fitri fleeing the Boko Haram security crisis. Synthesis and applications: This work is likely the first quantitative approach of bird harvest sustainability in Africa. It should contribute to fill a methodological and an information gap in the strategic planification of several multilateral environmental agreements like the African-Eurasian Waterbird Agreement and the Ramsar Convention. In particular, this work could help implementing adaptive management of natural resources (including birds) in Ramsar site management plans. African wetlands such as Lake Fitri may not be able to provide enough natural resources in the medium term for movements of displaced civilians forced by armed conflict into such biodiversity strongholds.
de Delphine Ducros, Rodolphe Devillers, Antoine Messager, Marie Suet, Abakar Saleh Wachoum, Clemence Deschamps, Babakar Matar Breme, Ib Krag Petersen, Yves Kayser, Nicolas Vincent‐Martin, et al.
In Journal of Applied Ecology, Online (August, 2023), 13
En ligne : besjournals.onlinelibrary.wiley.com[...]
Human pressure on ecosystems has strongly increased over the last decades and now impacts even the most remote regions. To help mitigate these impacts, it is crucial to designate protected areas in regions that retain a high level of ecological integrity. However, ecological data remain scarce for many such areas, making the systematic design of new protected zones challenging.
Following a request from local managers, we developed an original methodological approach to help design new zoning for a pre-existing protected area in a remote, data-poor Sahelian wetland of southern Chad, a vast area rich in biodiversity and exploited by diverse human activities. The method involved first collecting extensive aerial survey data (6252 records) on birds and mammals and then analysing this through a combination of distance sampling and density surface modelling. The biodiversity data, combined with ecological predictors, helped model species distribution layers that were then incorporated with socio-economic constraints into the systematic conservation planning tool Marxan.
This approach produced an array of protected zoning options that met three levels of conservation objectives set by experts, corresponding to proportions of individuals from given species to protect in the proposed protected area. Frequent exchanges with local managers allowed the analyses to be refined, resulting in seven potential scenarios to be considered for conservation purposes.
Synthesis and applications. In a context of high data scarcity, lack of access and short-term conservation objectives, this combined approach that optimizes newly obtained data via a suite of modelling tools can facilitate identifying and protecting natural areas in regions most in need of urgent conservation policy.
de Nadège Popoff, Elie Gaget, Arnaud Béchet, Laura Dami, Pierre Defos Du Rau, Ilse Geijzendorffer, Anis Guelmami, Jean-Yves Mondain-Monval, Christian Perennou, Marie Suet, et al.
In Biodiversity and conservation, 30 (July, 2021), 19
En ligne : link.springer.com[...]
The Mediterranean Basin is a biodiversity hotspot. Wetlands make a key contribution to this status, but many of them remain outside the Ramsar network fifty years after the establishment of the Ramsar Convention. Here we evaluate the extent to which the Mediterranean Ramsar network covers wetlands of international importance for wintering waterbirds using the Ramsar Convention criteria 2 (species of conservation concern), 5 (> 20,000 waterbirds) and 6 (1% of a population). These criteria were applied to 4186 sites in 24 Mediterranean countries using counts of 145 wintering waterbird species from 1991 to 2017. We identified 161 sites of international importance for waterbirds that have not yet been declared as Ramsar sites, which could be added to the 180 current Mediterranean Ramsar sites established based on waterbird criteria (criteria 5 and/or 6). Among these sites, a subset of 32 very important sites reached double the required level for at least one criterion and 95 were not protected by any site conservation status. Coastal wetlands represented half of the Ramsar gap for waterbirds. We identified that an additional 1218 monitored sites could be provisionally considered as internationally important and thus require more survey efforts to assess their status. This study highlights a lack of participation of the Mediterranean countries to build the Ramsar network for wetland protection. Our results should help policymakers and managers to prioritize future Ramsar site designation, notably in the Middle East and Western European region where important gaps were identified.Imputation of incomplete large-scale monitoring count data via penalized estimation
de Mohamed Dakki, Geneviève Robin, Marie Suet, Abdeljebbar Qninba, Mohammed A. El Agbani, Asmaâ Ouassou, Rhimou El Hamoumi, Hichem Azafzaf, Sami Rebah, Claudia Feltrup‐Azafzaf, et al.
In Methods in Ecology and Evolution, 12(6) (April, 2021)
En ligne : besjournals.onlinelibrary.wiley.com[...]
In biodiversity monitoring, large datasets are becoming more and more widely available and are increasingly used globally to estimate species trends and conservation status. These large-scale datasets challenge existing statistical analysis methods, many of which are not adapted to their size, incompleteness and heterogeneity. The development of scalable methods to impute missing data in incomplete large-scale monitoring datasets is crucial to balance sampling in time or space and thus better inform conservation policies. We developed a new method based on penalized Poisson models to impute and analyse incomplete monitoring data in a large-scale framework. The method allows parameterization of (a) space and time factors, (b) the main effects of predictor covariates, as well as (c) space–time interactions. It also benefits from robust statistical and computational capability in large-scale settings. The method was tested extensively on both simulated and real-life waterbird data, with the findings revealing that it outperforms six existing methods in terms of missing data imputation errors. Applying the method to 16 waterbird species, we estimated their long-term trends for the first time at the entire North African scale, a region where monitoring data suffer from many gaps in space and time series. This new approach opens promising perspectives to increase the accuracy of species-abundance trend estimations. We made it freely available in the r package ‘lori’ (https://CRAN.R-project.org/package=lori) and recommend its use for large-scale count data, particularly in citizen science monitoring programmes.
de Marie Suet, Juan Guillermo Lozano‐Arango, Pierre Defos du Rau, Clemence Deschamps, Mohammed Adam Abdalgader Mohammed, Elfirdous Elbashary Adam, Eltayeb Mohammed Eldegair, Mohamed Elmekki Ali Elbadawi, Ibrahim Mohammed Hashim, Noman Kirrem Kpoore, et al.
In Ibis, 163(2) (January, 2021), 16
En ligne : onlinelibrary.wiley.com[...]
In several regions of the world, the remoteness of potential bird hotspots and lack of trained observers have often prevented countries from effectively designing proper monitoring schemes at a national scale. For many countries, it is not known whether certain bird strongholds have been missed that should be included for more complete censuses. Such gaps at national scales, sometimes large, may be detrimental for global monitoring schemes. To address this, we used the irregular participation of Sudan to the International Waterbird Census (IWC) as a case study. We designed and tested a method based on remote-sensing data of the country’s lowlands to detect open water bodies in order to develop predictive models of the potential distribution of waterbird abundance and diversity. To identify open water bodies and their flooding duration, we used a Modified Normalized Difference Water Index (MNDWI) derived from Landsat 8 data. Field ornithological surveys were then used as ground-truth data to estimate the method’s accuracy. The statistical results (overall accuracy = 0.972; Kappa index = 0.93) confirmed its effectiveness. Remotely sensed water bodies and additional environmental covariates were then used to build simple habitat models of the distribution of waterbird abundance and diversity based on IWC field survey data. Of the 3119 remotely sensed clusters of open water bodies, three were predicted to host more than 10 000 waterbirds, 89 more than 1000 waterbirds and five more than 30 waterbird species. Located mainly in the southern agricultural floodplains along the main rivers, these predicted waterbird strongholds are therefore recommended for inclusion in the next IWC survey in Sudan. Our findings indicate that using remote sensing to identify open water bodies combined with simple statistical modelling is likely to be a cost-effective solution to improve IWC sampling and to enhance both waterbird and wetland monitoring in vast under-surveyed regions.
de M. S. Sayoud, H. Salhi, B. Chalabi, A. Allali, M. Dakki, A. Qninba, M. A. El Agbani, Hichem Azafzaf, Claudia Feltrup‐Azafzaf, H. Dlensi, et al.
In Biological Conservation, 206 (février 2017), 11-20
En ligne : www.sciencedirect.com[...]
The International Waterbird Census (IWC) is one of the most widespread biodiversity monitoring programs, assessing waterbird populations in the framework of several international agreements including the African-Eurasian migratory Waterbirds Agreement and the Ramsar Convention. In 2013, the IWC was coordinated for the first time across the whole of North Africa with the aim of developing recommendations for methodological improvements to current design in North Africa, as well as to update the conservation status of certain waterbird populations and wetlands of international importance. We show that coordinating the IWC across all five North African countries significantly improves knowledge of waterbird population sizes and distribution and confirmed that current North African Ramsar wetlands perform well in conserving waterbirds. Nevertheless, biodiversity conservation could potentially be further enhanced by designating additional Ramsar sites, which this study contributes to identifying. We show that reducing sampling effort by half over the entire region would have been sufficient to cover 100% of the species richness of wintering waterbirds recorded and > 98% of the total abundance. Finally, we show that larger wetlands are insufficiently sampled. These findings call for revised sampling design in a coordinated, region-wide framework. The maintenance, optimization and reinforcement of the IWC program over time on a regional scale, with the collected data made available in a shared database, seems essential in order to make appropriate conservation decisions for waterbirds and wetlands in the future. Adding a temporal dimension to these analyses will be critical to confirm the patterns observed in the 2013 census.Expected and unexpected effects of waterbirds on Mediterranean aquatic plants (2012)
de G. Gayet, N. Croce, Patrick Grillas, C. Nourry, Clemence Deschamps, P. Defos Du Rau
2012
