Les articles de Marie Suet

Monitoring major biodiversity stronghold in war zones: Model predicts Lake Chad remains Africa’s most important wetland for waterbirds

Wed, 8 Jul 2026 14:26:54

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.

Migration of humans fleeing conflict in the Lake Chad region may increase pressures on natural resources in Lake Fitri (Chad): A case study on waterbirds

Thu, 4 Jul 2024 15:39:30

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.

Exposure of wetlands important for nonbreeding waterbirds to sea-level rise in the Mediterranean

Fri, 17 May 2024 16:11:40

de Fabien Verniest, Thomas Galewski, Olivier Boutron, Laura Dami, Pierre Defos du Rau, Anis Guelmami, Romain Julliard, Nadège Popoff, Marie Suet, Loic Willm, et al.
In Conservation Biology, 2024 (May, 2024), e14288
En ligne : onlinelibrary.wiley.com[...]

Sea-level rise (SLR) is expected to cause major changes to coastal wetlands, which are among the world's most vulnerable ecosystems and are critical for nonbreeding waterbirds. Because strategies for adaptation to SLR, such as nature-based solutions and designation of protected areas, can locally reduce the negative effects of coastal flooding under SLR on coastal wetlands, it is crucial to prioritize adaptation efforts, especially for wetlands of international importance for biodiversity. We assessed the exposure of coastal wetlands important for nonbreeding waterbirds to projected SLR along the Mediterranean coasts of 8 countries by modeling future coastal flooding under 7 scenarios of SLR by 2100 (from 44- to 161-cm rise) with a static inundation approach. Exposure to coastal flooding under future SLR was assessed for 938 Mediterranean coastal sites (≤30 km from the coastline) where 145 species of nonbreeding birds were monitored as part of the International Waterbird Census and for which the monitoring area was delineated by a polygon (64.3% of the coastal sites monitored in the Mediterranean region). Thirty-four percent of sites were threatened by future SLR, even under the most optimistic scenarios. Protected study sites and study sites of international importance for waterbirds were, respectively, 1.5 and 2 times more exposed to SLR than the other sites under the most optimistic scenario. Accordingly, we advocate for the development of a prioritization scheme to be applied to these wetlands for the implementation of strategies for adaptation to SLR to anticipate the effects of coastal flooding. Our study provides major guidance for conservation planning under global change in several countries of the Mediterranean region.

Planning from scratch: A new modelling approach for designing protected areas in remote, data‐poor regions

Mon, 21 Aug 2023 15:18:22

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.

Anticipating the effects of climate warming and natural habitat conversion on waterbird communities to address protection gaps

Tue, 7 Feb 2023 15:47:00

de Fabien Verniest, Isabelle Le Viol, Romain Julliard, Laura Dami, Anis Guelmami, Marie Suet, Wed Abdou, Hichem Azafzaf, Nadjiba Bendjedda, Taulant Bino, et al.
In Biological Conservation, 279 (March, 2023), 10
En ligne : www.sciencedirect.com[...]

Thermal adjustment of waterbird communities to climate warming is crucial but hampered by natural habitat conversion, increasing their climatic debt. As it is, in contrast, facilitated in protected areas, assessing the adequacy of the current protected areas network with respect to future climate and land-use changes and identifying priority sites to protect is of major importance. In this study, we assess the thermal adjustment limitations that non-breeding waterbird communities might experience by the end of the 21st century in the Mediterranean region to highlight priorities for wetland protection. Priorities were set by combining the exposure of waterbird communities to natural habitat conversion and climate warming with their thermal specialization. The latter was calculated using winter abundance data of 151 species from 2932 sites of the International Waterbird Census in 21 Mediterranean countries. Exposure was assessed using future projections of temperature and land-use under four CMIP6 scenarios (SSP1–2.6, SSP2–4.5, SSP3–7.0, and SSP5–8.5). We found that strictly protected areas are located in wetlands whose waterbird communities, without protection, would likely experience high limitations in thermal adjustment in the coming decades. This highlights that the location of existing protected areas may effectively support the thermal adjustment of waterbird communities to future climate warming. However, 490 sites considered at risk lack protection, including 32 sites of international importance for waterbirds, stressing the need to strengthen the protected areas network in these sites in priority. Our study provides important guidance for conservation planning in the Mediterranean region to support waterbird responses to climate change. /
Dans notre étude, nous avons évalué les difficultés potentielles des communautés d’oiseaux d’eau hivernants à ajuster leur composition aux futurs changements de température en combinant la spécialisation thermique de la communauté avec deux métriques d’exposition à l’augmentation future des températures hivernales et à la perte future d’habitats naturels à l’horizon 2090 selon quatre scénarios futurs différents. Nous avons ainsi constaté que les aires protégées, et notamment celles strictement protégées, sont situées dans des zones humides dont les communautés d'oiseaux d'eau, sans protection, auraient probablement connu de fortes difficultés d'ajustement thermique au cours des prochaines décennies. Cela met en évidence la pertinence de l'emplacement des aires protégées existantes qui pourront faciliter de manière efficace l'adaptation thermique des communautés d'oiseaux d'eau au réchauffement climatique futur. Cependant, nous avons également identifié 490 sites à risque et ne bénéficiant d'aucun statut de protection, dont 32 sites d'importance internationale pour les oiseaux d'eau, ce qui souligne la nécessité de renforcer le réseau d'aires protégées méditerranéen dans ces sites en priorité.

Wintering waterbirds in North Africa 1990-2017 (2022)

Thu, 2 Jun 2022 11:39:24

de Mohamed Dakki, Geneviève Robin, Marie Suet, Abdeljebbar Qninba, Mohammed A. El Agbani, Asmaâ Ouassou, Rhimou El Hamoumi, Hichem Azafzaf, Wed A. L. Ibrahim, Khaled Etayeb, et al.
Wadden Sea Flyway Initiative p/a CWSS. 2022, 63-67

In North Africa, waterbird counts have been carried out since the 1960s but only became regular in the 1980s. However, the lack of stable funding, of suitable optical equipment, of a stable and reliable national network of counters in the five countries, and of facilities to cover large areas and move from one site to another, meant that surveys never covered all the sites and were not really carried out regularly. It was with the setting up of the Mediterranean Waterbirds Network in 2012 that a certain regularity of counts was established, with financial and technical support, and with the development of the Medwaterbirds database. This database contains 36,436,391 records but suffers from over 60% missing data for 1990-2017. In order to accommodate this missing data issue, a new imputation method, LORI, was applied to the Medwaterbirds data set using multiple site- and/or year-specific covariates. North African trends for 16 species were assessed and discussed with respect to the corresponding trends at the international level (AEWA CSR 8).
Because the issue of missing data is an acute one in ecological monitoring, we argue that our modelling tool could be useful for many studies on wildlife. The joint work with other Mediterranean countries, the possible monitoring of breeding birds in the Mediterranean, and synchronous counts with the East Atlantic Flyway countries could all be considered as lines of action to improve these analyses, but also their interpretation in relation to the status of populations.

Gap analysis of the Ramsar site network at 50: over 150 important Mediterranean sites for wintering waterbirds omitted

Wed, 7 Jul 2021 14:08:13

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

Fri, 9 Apr 2021 18:17:28

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.

Improving waterbird monitoring and conservation in the Sahel using remote sensing: a case study with the International Waterbird Census in Sudan

Thu, 28 Jan 2021 14:56:27

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.

Confirmation de l'implantation de la Martre des pins Martes martes (Linnaeus, 1758) en Camargue / Confirmed establishment of the Pine Marten Martes martes (Linnaeus, 1758) in the Camargue

Thu, 21 Dec 2017 17:19:39

de Anthony Olivier, Marie Suet, Jean-Yves Mondain-Monval
In Nature de Provence, Online (Nov 2017), 1-5
En ligne : www.cen-paca.org[...]

Découverte en Camargue à l’aube du nouveau millénaire, la Martre des pins Martes martes (Linnaeus, 1758) n’avait fait l’objet que de très peu de mentions (n=4) jusqu’en 2010. De nouvelles observations (n=15) réparties le long d’une vingtaine de kilomètres de ripisylve démontrent la persistance de l’espèce dans le delta. Cette population est originale du fait de son (supposé) isolement géographique et du caractère très peu forestier de la Camargue (les boisements composent 3,5% de la superficie du Parc naturel régional de Camargue). De plus, il s’agit de la seule population connue à ce jour dans la plaine méditerranéenne française. / Discovered in the Camargue at the beginning of this new millennium, the Pine Marten Martes martes (Linnaeus, 1758) was only reported on rare occasions up to 2010 (n=4). New observations (n=15) made along a 20km stretch of an alluvial forest indicate the persistence of this species in the Rhone River Delta. This population is original, because of its (supposed) geographic isolation and the small amount of forest in the Camargue (only 3.5% of the Camargue Regional Natural Park). This population is the only one known up to now in the french mediterranean plain.

Epizoic algae distribution on the carapace and plastron of the European pond turtle (Emys orbicularis, Linnaeus, 1758): A study from the Camargue, France

Tue, 8 Nov 2016 15:58:25

de Stéphanie Fayolle, Camille Moriconi, Benjamin Oursel, Claire Koenig, Marie Suet, Sébastien Ficheux, Maxime Logez, Anthony Olivier
In Algologie, 37(4) (November 2016), 1-12
En ligne : www.bioone.org[...]

We investigated epizoic algal assemblages on the shell of European pond turtles ( Emys orbicularis ) during two years (2013-2014). A total of 60 Emys orbicularis were captured in the three shallow Mediterranean wetlands located in Camar gue. Epizoic algae on the plastron (below the shell) and carapace (above the shell) were sampled, identified and counted. Seventy-seven epizoic algal species were identified on the carapac e and plastron and comprised in 51 Bacilla riophyta, 11 Chlorophyta, 7 Cyanophyta, 6 Euglenophyta, 1 Dinophyta and 1 Xanthophyta taxa. Our findings indicated a distinct distribution of epizoic algae according to taxonomical group density; Chlorophyta, and Cyanophyta were dominant on the carapac e whereas the Xanthophyta (genus Vaucheria sp.) was dominant on the plastron. Turtle- associated algal assemblages did not differ among the wetlands / Nous avons réalisé une étude sur l’assemblage des algues épizoiques sur la carapace de Cistudes (Emys orbicularis) au cours de deux années (2013-2014). Soixante Emys orbicularis ont été collectés dans trois marais méditerranéens situés en Camargue. Les algues épizoiques ont été identifiées et dénombrées sur le plastron (dessous la carapace) et sur la dossière (dessus la carapace). Au total, 77 espèces d’algues épizoiques ont été inventoriées sur la dossière et sur le plastron réparties en 51 Bacillariophyta, 11 Chlorophyta, 7 Cyanophyta, 6 Euglenophyta, 1 Dinophyta and 1 Xanthophyta. Nos recherches ont mis en évidence une distribution originale des algues épizoiques selon leur groupe taxonomique. Parmi les principaux groupes, les chlorophytes et les cyanophytes filamenteuses sont prédominantes sur la dossière tandis que le groupe des xanthophytes (genus Vaucheria sp.) se développe sur l’ensemble des plastrons étudiés. Aucune différence dans les assemblages algaux n’a été observée entre les 3 marais étudiés.