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Les articles de Thomas Galewski
de Elie Gaget, Jon E. Brommer, Thomas Galewski
In Biodiversity and conservation, (en ligne) (September, 2025)
En ligne : doi.org[...]
European waterbird and seabird populations have been threatened by anthropogenic activities for decades. Effective strategies are needed to restore both populations and their habitats. However, the temporal period used to define the state of reference when setting restoration targets requires careful considerations to avoid the risk of shifting baseline. A risk of shifting baseline occurs if a population decreases before the time period used to set a baseline. In Europe, most bird monitoring schemes started after the 1970s, yet significant changes in population trends were already reported earlier in the 20th century. We assessed the risk of shifting baseline for 88 out of 170 waterbird and seabird species breeding in Europe. Building on historical ecology, we reconstructed population trends between 1900 and 2018 from information collected in both historical literature and monitoring scheme reports. Historical trends confirm variations in population trends for several waterbird and seabird species over the period 1900-1970, with 35 decreasing species, 38 fluctuating species, 15 increasing species and 82 species with unknown trends. A high risk of shifting baseline was identified for 28 species, for which restoration targets must consider historical trends spanning at least a century. The risk was low for 12 species, probably low for 41 species, probably high for 7 species and uncertain for 82 species. Our study highlights the crucial role of historical data collected prior to the large-scale implementation of standardized abundance monitoring, as it allows for the identification of appropriate baselines to guide the restoration of waterbird and seabird breeding populations.
de Dilara Arslan, Elie Gaget, Kerim Cicek, Anthony Olivier, Thomas Galewski, Ömer Döndüren, Anis Guelmami, Lisa Ernoul, Arnaud Béchet
In BMC Ecology and Evolution, 25(1) (June, 2025), 58
En ligne : doi.org[...]
Wetlands have been some of the most destroyed ecosystems over the last century, with important land-use changes resulting from agricultural, industrial, and urban development. Gediz Delta is a large wetland on the Aegean coast of Western Türkiye with natural areas affected by conversion to agriculture and urban developments from the Izmir metropolis. We assessed the effects of landscape type (natural, agricultural, and urban) on the composition of breeding bird (90 species) and reptile (14 species) communities in the Gediz Delta between 2019 and 2021. We used generalized linear models to estimate the effect of landscape types on community indexes and joint species distribution models to assess how species-specific habitat preferences explained their responses to landscape type.Première mention française de la Gallinule africaine Paragallinula angulata
de Jacques Artieda, Thomas Galewski, Bernard Recorbet, Frédéric Armani
In Ornithos, 171 (Avril, Mai, Juin 2025), 28-35
Le 6 mars 2024, Jacques Artieda observe et photographie un petit rallidé qu'il n'identifie pas tout de suite sur la zone d'humide d'Air Corsica, au sud-est d'Ajaccio, en Corse-de-Sud. Cette observation se révèlera être la première mention pour la France de la Gallinule africaine, identifiée grâce à la publication des photos sur internet et aux réseaux sociaux. Cette note revient sur cette observation, l'identification de l'oiseau et apporte des éléments contextuels sur l'apparition de l'espèce dans le paléarctique occidental.Exposure of wetlands important for nonbreeding waterbirds to sea-level rise in the Mediterranean
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.Compte rendu ornithologique : Camargue, Crau, Alpilles, pour les années 2013 à 2018
de Yves Kayser, Thomas Blanchon, Thomas Galewski, Jocelyn Champagnon, Marc Thibault, Gregoire Massez, Christophe Pin, Nicolas Sadoul, Rémi Tiné, Jérémiah Petit, et al.
In Alauda, 92(1) (2024), 3-96
Ce 26e rapport ornithologique de Camargue s'inscrit dans la continuité d'une longue tradition commencée en 1930, peu après la création de la Réserve Botanique et Zoologique de Camargue, devenue par la suite Réserve Nationale de Camargue. L'ornithologie a toujours tenu une place importante en Camargue. Entre 1930 et 2012, 25 rapports ont été publiés. Ce rapport ornithologique couvre l'ensemble de la Camargue, de la Crau et des Alpilles et les années 2013 à 2018. La pression d'observation n'a cessé d'augmenter avec l'augmentation des données disponibles. Alors que l'édition précédente était basée sur 400 000 données d'observation, plus de 900 000 données d'observation ont été réalisées sur la période 2013 à 2018. Certains faits importants comme le déplacement de la colonie de Flamants roses Phoenicopterus roseus de l'étang du Fangassier (Salin-de-Giraud) sur les salins d'Aigues-Mortes. Ce constat est toujours lié aux difficultés de mise en eau suite au démantèlement des stations pompages ayant eu lieu après la vente progressive de 6500 ha de terrains par la Compagnie des Salins du Midi au Conservatoire du Littoral. À cela, s'est ajouté la présence régulière de prédateurs sur le site du Fangassier comme le Renard roux Vuipes vulpes ou le Grand-duc d’Europe Bubo bubo. Ces six années ont vu l’apparition de neuf nouvelles espèces sur la zone étudiée. En hivernage, une nette baisse du nombre d'Oies cendrées Anser anser été constatée avec des effectifs passant de 4800 individus en 2013 à 2400 en 2018. Les effectifs de Fuligule milouin Aythya ferina sont également en chute constante. Quant à l'hivernage du Fuligule morillon Aythya fuligula, il est pour ainsi dire devenu relictuel. Plusieurs nouvelles observations hivernales de Crabiers chevelus Ardeola ralloides ont été effectuées sur la période. Le nombre de Grues cendrées Grus grus hivernantes poursuit sa progression pour dépasser les 15000 oiseaux en 2018. Une nette baisse des effectifs nicheurs de Crabier chevelu Ardeola ralloides a été observée. L'effectif est passé de plus de 600 couples en 2014 à 189 en 2018. Il en est de même pour le Héron cendré Ardea cinerea qui voit le nombre de nicheurs passer de 793 couples en 2014 à 418 en 2018. En revanche, certaines espèces comme le Grand Cormoran Phalacrocorax carbo, la Spatule blanche Platalea leucorodia ou la Cigogne blanche Ciconia ciconia montrent des augmentations progressives du nombre de reproducteurs et d’autres, comme l'Ibis falcinelle Plegadis faicinellus continue leur progression spectaculaire. La Talève sultane Porphyrio porphyrio est à nouveau présente dans bon nombre de marais d’eau douce suite à la vague de froid de 2012 qui avait nettement freiné son expansion. Il a été constaté en Crau un fort taux de consanguinité chez le Ganga cata Pterocles alchata induisant un nombre de jeunes peu élevé survivant au premier hiver. La Glaréole à collier Glareola pratincola se maintient autour de 70 couples chaque année, par contre, un nombre important de jeunes a été élevé en 2017 (1,9 jeune à l'envoi par couple). Chez les laro-limicoles coloniaux de Camargue, la baisse du nombre de nicheurs continue chez le Goéland leucophée Larus michahellis alors que l'Avocette élégante Recurvirostra avosetta, le Goéland railleur Chroicocephalus genei et la Sterne naine Sternula albifrons ont connu des effectifs records depuis 1956. L’Aigle de Bonelli Aquila fasciata a connu une très mauvaise année de nidification en 2018 avec aucun jeune à l'envol. Durant les périodes hivernales et migratoires, il a été mis en évidence une très forte augmentation du nombre de données concernant le Busard pâle Circus macrourus et le Pouillot à grands sourcils Phylloscopus inornatus. Les observations de Pouillot sibérien Phyloscopus collybita tristis ont aussi augmenté. Enfin, une très forte hausse du nombre de contacts (tant au niveau des sites où l'espèce est présente qu'à celui du nombre de données) a été enregistrée chez le Bruant proyer Emberiza calandra en période de nidification.On the need and difficulty of evaluating management strategies improving species persistence
de Elie Gaget, Thomas Galewski, Jon E. Brommer, Isabelle Le Viol, Frédéric Jiguet, Nicola Baccetti, Tom Langendoen, Blas Molina, Filipe Moniz, Caroline Moussy, et al.
In Animal Conservation, 27(1) (February, 2024), 21-22
En ligne : onlinelibrary.wiley.com[...]
Discussion élargie sur les besoins d'évaluer les mesures de gestion favorisant la persistance des espèces, mais aussi des difficultés à mettre en place de telles évaluations sur les canards.
de Elie Gaget, Thomas Galewski, J. E. Brommer, Isabelle Le Viol, F. Jiguet, N. Baccetti, T. Langendoen, B. Molina, F. Moniz, C. Moussy, et al.
In Animal Conservation, 27(1) (February, 2024), 5-16
En ligne : onlinelibrary.wiley.com[...]
Climate warming is driving species to shift their geographical distribution poleward to track suitable climatic conditions. Two strategies have been suggested to help species respond to climate warming: facilitating distribution change or improving persistence. We questioned whether habitat management in favour of duck hunting activities interacted with duck responses to climate warming. We studied non-breeding waterbird community changes (110 species) over 28 years at 851 sites in South-West Europe, where habitat management is a common practice to attract and hunt ducks. We hypothesized that duck species targeted by habitat management do not need to track temperature changes as much as non-hunted species, because of the availability of suitable habitats provided by hunting land managers. We used the community temperature index (CTI) to assess the temporal responses of communities and species to climate warming. We compared the effect of hunting status with other functional traits on species responses, controlling for phylogenetic relatedness. The CTI trend has increased over the study period, indicating a community adjustment to climate warming. However, hunted ducks contributed to almost 40% of the negative contributions to this community adjustment, suggesting that hunted ducks do not shift their distribution as much as the other waterbirds do. Winter fidelity associated with the provision of attractive feeding grounds might explain why ducks did not seem to shift their distribution in response to climate warming. This study suggests the broad impact of human activities on wildlife, including on large-scale distribution processes, and questions the long-term consequences on duck populations.
de Thomas Galewski
Tour du Valat, Arles : Université de Montpellier, école doctorale Gaïa, 2024, 250
L’axe de recherche, que l'auteur coordonne et qu'il présente dans les chapitres suivants, cherche à étudier la réponse de la biodiversité des zones humides méditerranéennes aux facteurs de changement. La première tâche a été d’identifier un modèle biologique bénéficiant d’un suivi sur le long terme et sur l’ensemble du bassin méditerranéen, qui soit intimement lié aux zones humides et qui présente un intérêt pour la conservation. Le choix s’est porté sur les oiseaux.
Dans le Chapitre 2, Thomas Galewski présente comment les recherches menées avec ses étudiants ont permis à l’OZHM d’améliorer l’utilisation d’indices multispécifiques pour estimer l’état de conservation et les tendances de la biodiversité des zones humides méditerranéennes, et comment, à l’échelle locale, ils ont pu mieux gérer deux contraintes inhérentes à l’utilisation de ces indices, à savoir des données hétérogènes entre espèces d’une même communauté et un état de référence trop récent.
Le Chapitre 3 illustre comment ils ont cherché à mieux comprendre les mécanismes d’impact de deux pressions majeures pour la biodiversité des zones humides méditerranéennes à savoir les changements d’usage des sols et le changement climatique. A l’échelle de la Camargue, ils se sont plus particulièrement intéressés à l’intensification des systèmes rizicoles, une culture majeure dans les zones humides méditerranéennes. A l’échelle méditerranéenne, ils se sont intéressés à l’impact du changement climatique mais également à l’impact de l’interaction entre changement climatique et changements d’usage des sols sur la capacité des communautés d’oiseaux d’eau à répondre aux changements en cours. Ces résultats ont permis de mieux identifier certains des leviers qui permettraient de conserver ou restaurer les communautés d’oiseaux et leurs habitats.
Dans le Chapitre 4, ils évaluent le rôle des politiques publiques dans la conservation des oiseaux d’eau hivernants en Méditerranée. Ils ont d’abord cherché à mesurer l’efficacité du réseau d’aires protégées par la Convention de Ramsar et/ou de certains accords internationaux pour améliorer l’état de conservation des oiseaux et permettre leur ajustement au changement climatique. Puis ils ont évalué les lacunes dans le réseau d’aires protégées actuel, y compris pour relever les défis de demain, un travail qui pourrait aider à orienter les futures politiques de conservation.Field margins as substitute habitat for the conservation of birds in agricultural wetlands
de Pierre Mallet, Arnaud Béchet, Clelia Sirami, François Mesléard, Thomas Blanchon, Francois Calatayud, Thomas Dagonet, Elie Gaget, Carole Leray, Thomas Galewski
In Peer Community Journal, 3 (August, 2023)
En ligne : peercommunityjournal.org[...]
Breeding birds in agricultural landscapes have declined considerably since the 1950s and the beginning of agricultural intensification in Europe. Given the increasing pressure on agricultural land, it is necessary to identify conservation measures that consume little productive land. We tested the compensation hypothesis which states that field margins may represent substitute habitats for bird species in agricultural wetlands. We monitored bird species in 86 crop fields in rice paddy landscapes of Camargue (southern France), a wetland of international importance for birds. We investigated whether the area of three types of field margins (reed strips, grass strips and hedgerows) within a 500 meter buffer around the centroid of each crop fields had an effect on the abundance of bird species from three groups defined based on their primary habitat (reedbeds, grasslands, and forest edge species). We controlled for the area of each type of semi-natural habitat (wetlands, grasslands, and woodlands), crop diversity (rice, wheat, alfalfa, rape, and market gardening) and mean crop field size. Results show partial support of the compensation hypothesis with species-dependent responses to primary and substitute habitat area. Some species within the reedbed and grassland bird guilds are favored by the area of their primary habitat as well as by the area of field margins, in line with the compensation hypothesis. Eurasian reed warbler is favored by the area of both wetlands and reed strips. Corn bunting is favored by grassland and grass strip areas. We could not confirm the compensation hypothesis for other species. However, this may be due to the fact that most of these species did not respond to their primary habitat. These results therefore suggest that field margins may represent substitute habitats for some species but further studies, in contexts where species are strongly associated with their primary habitat, would be needed to confirm the generality of this hypothesis. Our results also suggest that species response to increasing the area of a field margin type may vary among guilds and even within guilds. Therefore, it may be difficult to favor all species within a given landscape and management actions may need to be tailored to whichever species are locally associated with the highest conservation priority. To tackle this challenge, it may be necessary to design landscape management actions at different spatial scales.Past, present, and future of the Living Planet Index
de Sophie E. H. Ledger, Jonathan Loh, Rosamunde Almond, Monika Bohm, Christopher F. Clements, Jessica Currie, Stefanie Deinet, Thomas Galewski, Monique Grooten, Martin Jenkins, et al.
In npj Biodiversity, 2(1) (June, 2023), 1-13
En ligne : www.nature.com[...]
As we enter the next phase of international policy commitments to halt biodiversity loss (e.g., Kunming-Montreal Global Biodiversity Framework), biodiversity indicators will play an important role in forming the robust basis upon which targeted, and time sensitive conservation actions are developed. Population trend indicators are one of the most powerful tools in biodiversity monitoring due to their responsiveness to changes over short timescales and their ability to aggregate species trends from global down to sub-national or even local scale. We consider how the project behind one of the foremost population level indicators - the Living Planet Index - has evolved over the last 25 years, its value to the field of biodiversity monitoring, and how its components have portrayed a compelling account of the changing status of global biodiversity through its application at policy, research and practice levels. We explore ways the project can develop to enhance our understanding of the state of biodiversity and share lessons learned to inform indicator development and mobilise action.
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.
de Fabien Verniest, Thomas Galewski, Romain Julliard, Anis Guelmami, Isabelle Le Viol
In Conservation Science and Practice, Online (October, 2022), 17
En ligne : onlinelibrary.wiley.com[...]
Identifying sites that are both important for biodiversity and likely to be heavily affected by anthropogenic pressures in the future is crucial to settle priorities in the implementation of conservation measures, such as the designation of new protected areas. Although assessing the exposure of terrestrial Key Biodiversity Areas to global change would support such identification, it has never been performed to our knowledge. In addition, previous exposure assessments have been limited to few metrics of climate change and have not considered other global change components. Here, we assess the extent to which terrestrial (including inland water) Key Biodiversity Areas are exposed to future climate change and land-use modifications in 29 countries of the Mediterranean region, and identify countries where additional protection efforts are most needed. To this end, we calculated two local and two regional exposure metrics using projections of climate and land-use for late 21st century under four scenarios that were used in the sixth assessment report of the Intergovernmental Panel on Climate Change (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5). These four exposure metrics were subsequently combined into an exposure index ranking sites from least to most exposed to climate and land-use changes. We highlight that the most exposed non-protected Key Biodiversity Areas are located in countries where the protection of this network is lowest (i.e., high number and percentage of non-protected sites). We also found that Key Biodiversity Areas were overall more exposed than the rest of the study zone and that the sites most in need of conservation actions were similar across future scenarios. Our study reinforces the pressing necessity to strengthen and extend conservation measures in Mediterranean Key Biodiversity Areas, especially in Middle-East and Maghreb countries whose Key Biodiversity Areas are both at risk to be strongly affected by anthropogenic pressures and insufficiently protected.
de Dilara Arslan, Lisa Ernoul, Arnaud Béchet, Ömer Döndüren, Mehmet Sıkı, Thomas Galewski, Dilara Arslan, Lisa Ernoul, Arnaud Béchet, Ömer Döndüren, et al.
In Marine and Freshwater Research, Online (October, 2022)
En ligne : www.publish.csiro.au[...]
Bird species have been studied and documented abundantly in the past decades and are good indicators of ecosystem conditions, providing useful information of the changes in the ecological state of wetlands over time. However, monitoring data for birds in wetland sites are often disparate and not homogeneous over time and among species, which complicates the interpretation of trends.
We examined historical literature from 1835 to 2019, complemented by an expert knowledge survey and citizen-science databases to estimate the abundance of species, and evaluated changes in the structure and composition by average bird abundances.Key results Our results suggested that land-cover and land-use changes have shaped the local bird community, with a decline in agricultural and grassland bird species as a result of changes in agricultural practices. Coastal wetland and marine birds have increased in abundance, most probably linked to the extension of saltpans and successful conservation measures.
hese trends in bird communities demonstrate the impacts of different land management strategies on biodiversity.Implications This methodology can be replicated in other Ramsar and wetland sites around the world to raise new conservation issues and improve site conservation.
de Timothée Schwartz, Aurélien Besnard, Christophe Pin, Olivier Scher, Thomas Blanchon, Arnaud Béchet, Nicolas Sadoul
In Conservation Biology, Online (September, 2022)
En ligne : onlinelibrary.wiley.com[...]
By rapidly modifying key habitat components, habitat restoration is at risk of producing attractive cues for animals without providing habitats of sufficient quality. As such, individual fitness components such as reproduction could be reduced and restored habitats could become ecological traps. This risk notably appears by using artificial constructions in restoration projects, yet few studies have evaluated their efficacy in a robust way. In this study, we investigated this by analysing 154 islets that were created or restored in order to improve the conservation status of seven colonial Laridae species in the south of France. During a 10-year study period (2007 to 2016), we compared occupancy dynamics and breeding parameters of these species between the restored sites and 846 unmanaged nesting sites. We also explored species’ preference for different nesting site characteristics and their respective effect on breeding parameters. We found that restored nesting sites were more attractive than unmanaged sites for all species except the black-headed gull. Colonization probability was higher in sites already used by other species the previous year. Abandonment probability was lower when breeding was successful the previous year in all species except the Sandwich tern, and decreased with the size of the colony the previous year in four of the seven species. Breeding parameters were significantly higher on managed sites. Distance from the shore was an important attractive characteristic of artificial nesting sites in all species. Other nesting site characteristics had species-specific effects on colonization, abandonment and breeding success. These results indicate that managed nesting sites are successful conservation tools for colonial Laridae in the Mediterranean and do not act as ecological traps. Our study shows that the test of the ecological trap hypothesis is a robust way to evaluate the success of restoration projects of breeding habitats.
de Pierre Mallet, Arnaud Béchet, Thomas Galewski, François Mesléard, Samuel Hilaire, Gaëtan Lefebvre, Brigitte Poulin, Clelia Sirami
2022, 8
En ligne : www.sciencedirect.com[...]
Increase in pesticide use and landscape homogenization are two key drivers of the decline in farmland biodiversity. The effects of these two drivers are often complex, interactive and vary among taxonomic groups. Our study tested the hypothesis that pesticide use influences the effect of different components of landscape complexity on different taxonomic groups. We sampled 32 rice paddy landscapes of 1 * 1 km in the Camargue (south of France), a wetland internationally recognized as an exceptional biodiversity hotspot. We assessed the abundance and diversity of 7 taxa (plants, bees, butterflies, hoverflies, carabids, spiders and birds) in 3 or 4 crop fields per landscape. For each landscape, we measured the length of different field margins (ditch, grass strip, hedgerow), the proportion of semi-natural areas and crop diversity. For each field, we measured management intensity by the treatment frequency index (TFI) of pesticides. We then tested our hypothesis across 118 fields. Our results show that different components of landscape complexity influence different taxonomic groups: crop diversity and the length of ditches influence bee abundance and species richness, the proportion of semi-natural areas influence spider abundance and species richness, and the length of grass strips influences bird abundance. Moreover, we show that local pesticide use modulates these effects, with more positive effects of landscape complexity in intensively-managed fields. However, we found no interactive effect between landscape complexity and field management for plants, butterflies, hoverflies and carabids. Our study therefore suggests that different components of landscape complexity need to be maintained in order to preserve multiple taxonomic groups. Moreover, it suggests that increasing landscape complexity is particularly relevant to restore biodiversity in intensively-managed fields. Agricultural policies should therefore support the simultaneous increase in semi-natural areas, field margins length and crop diversity to conserve a wide range of taxonomic groups in intensively-managed rice paddy landscapes.
de Timothée Schwartz, Aurélien Besnard, Jesus M. Aviles, Teresa Catry, Andrzej Gorski, Orsolya Kiss, Deseada Parejo, Edmunds Račinskis, Laimonas Sniauksta, Milda Šniaukštienė, et al.
In Oecologia, 197 (August, 2021), 167–178
En ligne : doi.org[...]
Life-history theory predicts that animals should develop adaptive trade-offs between survival and reproduction to maximize their fitness. This results in a continuum of life-history strategies among species, ranging from slow to fast paces-of-life. The optimal pace-of-life has been shown to vary within environmental gradients, with a commonly observed pattern of a slow-to-fast continuum from the tropics to the poles. Within species, pace-of-life variability has however received much less attention. In this study, we investigated whether or not the pace-of-life of populations within a species follows the expected slow–fast continuum associated with latitude. We analysed the variability of life-history strategies among populations of the European roller Coracias garrulus, a long-distance migratory species, comparing breeding parameters and adult survival between populations across a latitudinal gradient. The findings showed a negative correlation between survival and clutch size in roller populations, with a slower pace-of-life in the northern populations and a faster pace-of-life in the southern populations: a reverse gradient to what might be expected from inter-specific studies. These results suggest that northern populations would benefit from measures enhancing adult survival probability, such as reduction in harvesting rates, while southern populations would respond better to actions favouring reproductive success, such as nesting site provisioning. This study highlights that life-history traits can vary substantially between populations of a single species with a large latitudinal breeding range, and pinpoint how knowledge about this variability may be key in anticipating different populations’ responses to threats as well as to conservation strategies.
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.
de Nigel G. Taylor, Patrick Grillas, Hazem Al Hreisha, Özge Balkız, Maud Borie, Olivier Boutron, Ana Catita, Jocelyn Champagnon, Semia Cherif, Kerim Cicek, et al.
In Regional Environmental Change, Online (2021), 25
Wetlands are critically important for biodiversity and human wellbeing, but face a range of challenges. This is especially true in the Mediterranean region, where wetlands support endemic and threatened species and remain integral to human societies, but have been severely degraded in recent decades. Here, in order to raise awareness of future challenges and opportunities for Mediterranean wetlands, and to inform proactive research and management, we identified (a) 50 key issues that might affect Mediterranean wetlands between 2020 and 2050, and (b) 50 important research questions that, if answered, would have the greatest impact on the conservation of Mediterranean wetlands between 2020 and 2050. We gathered ideas through an online survey and review of recent literature. A diverse assessment panel prioritised ideas through an iterative, anonymised, Delphi-like process of scoring, voting and discussion. The prioritised issues included some that are already well known but likely to have a large impact on Mediterranean wetlands in the next 30 years (e.g. the accumulation of dams and reservoirs, plastic pollution and weak governance), and some that are currently overlooked in the context of Mediterranean wetlands (e.g. increasing desalination capacity and development of antimicrobial resistance). Questions largely focused on how best to carry out conservation interventions, or understanding the impacts of threats to inform conservation decision-making. This analysis will support research, policy and practice related to environmental conservation and sustainable development in the Mediterranean, and provides a model for similar analyses elsewhere in the world.
de Timothée Schwartz, Arnaud Genouville, Aurélien Besnard
In Ecology and Evolution, 10(24) (December, 2020), 13649-13663
En ligne : onlinelibrary.wiley.com[...]
Artificial devices are increasingly used in conservation measures to mitigate the disappearance of natural habitats. However, few studies have demonstrated their benefits for the target species, and they may pose a risk of creating ecological traps. This occurs when lower individual fitness is found in artificial habitats that are more attractive than their natural equivalents. In this study, we tested the ecological trap hypothesis on a dense population of European rollers Coracias garrulus breeding in both natural cavities and nest boxes. Our initial prediction was that the more stressful microclimatic conditions of nest boxes would lead to reduced fitness of European rollers, thus creating an ecological trap. The results showed that nest boxes were preferred over natural cavities. Despite significantly more extreme microclimatic conditions in nest boxes, we found similar breeding parameters between artificial and natural nest types. Our results also suggest that European rollers selected the nest boxes which best buffered the temperature, thus avoiding potential ecological traps. Overall our results led to the conclusion that nest boxes do not create ecological traps for European rollers in this study area. However, other species may be more sensitive to microclimatic variations or less able to avoid the least favorable nest boxes. These findings could help to inform the placement of nest boxes in order to reduce extreme temperatures and variation in humidity rates. Future studies could compare nest types for other fitness parameters, such as juvenile body condition or survival. We also recommend the ecological trap hypothesis as a useful framework to evaluate the outcomes of artificial devices used for conservation.Geographic variation in body size among French populations of the European pond turtle
de Fabien Mignet, Jean-Yves Barnagaud, Laurent Barthe, Albert Bertolero, Valerie Bosc, Florine Escot, Romain Fleuriau, Laurent Joubert, André Joyeux, Damien Lerat, et al.
In Amphibia-Reptilia, 42(2) (October, 2020), 1-11
En ligne : brill.com[...]
The processes underlying macroecological gradients in body size are widely debated, in part because their intraspecific variability remains poorly described even in well-studied taxa such as vertebrates. In this study, we investigated how climate, habitat, genetic lineage and sex explain body size variations in French populations of the European pond turtle (Emys orbicularis). We measured 7016 adult individuals captured in 41 populations, covering most of the species’ distribution in metropolitan France, including Corsica. Body size variation in our sample was wide and comparable to that found across the species’ worldwide range. Variation was similar in magnitude at regional and local levels, suggesting that body size is influenced by local factors as much as by regional factors such as climate or genetic lineage. Smaller sizes were associated with Mediterranean or altered oceanic climates, and with two lineages (E. o. galloitalica and E. o. galloitalica/E. o. orbicularis), while larger sizes were associated with northern environments and the orbicularis lineage. Body size variations recorded at local level reflect an adaptive response to environmental constraints, suggesting that habitat is also an important factor in understanding size variation.
de Elie Gaget, Thomas Galewski, Frédéric Jiguet, Anis Guelmami, Christian Perennou, Coralie Beltrame, Isabelle Le Viol
In Conservation Biology, 34(4) (August, 2020)
En ligne : conbio.onlinelibrary.wiley.com[...]
While the impacts of climate and land use changes on biodiversity have been widely documented, their joint effects remain poorly understood. We evaluated how non-breeding waterbird communities adjust to climate warming along a gradient of land use change. Using mid-winter waterbird counts (132 species) at 164 major non-breeding sites in 22 Mediterranean countries, we assessed the changes in species composition during 1991–2010, regarding thermal niche position and breadth, in response to regional and local winter temperature anomalies and to natural habitat conversion. We showed that in response to the temperature increase, communities became relatively richer in warm-dwelling species, but less where natural habitat conversion occurred. At the sites affected by natural habitat conversion, the overall species richness decreased with time, while the abundance relatively increased for the species with a broader thermal niche, independently of their thermal affinities. The strong negative relationship between natural habitat conversion and community adjustment to temperature increases suggests an antagonistic interaction between climate warming and habitat change. Indeed, we found no evidence of community adjustment to climate warming when natural habitat conversion was higher than 5% over 15 years. These results underline the importance of habitat conservation in community adjustment to climate warming. Article impact statement: Waterbird communities do not adjustment to climate warming when natural habitat conversion is >5% over 15 years. This article is protected by copyright. All rights reserved
de Orsolya Kiss, Ines Catry, Jesus M. Aviles, Sanja Barisic, Tatiana Kuzmenko, Svilen Cheshmedzhiev, Ana Teresa Marques, Angelo Meschini, Timothée Schwartz, Béla Tokody, et al.
In Bird Study, 67(2) (July, 2020), 1-17
En ligne : www.tandfonline.com[...]
We used MaxEnt for species distribution modelling based on the reconstructed distribution map of the species.
Our results suggest that during glacial periods Rollers persisted in small southern refugia, and then spread and colonized northern latitudes during the mid-Holocene. In the future, our models forecast a shift in climatically suitable range towards northern latitudes and an overall small range contraction (4.5–5.5%). Warmer temperatures will increase climate suitability in northern countries where the species is currently declining or became locally extinct. On the other hand, wide suitable areas under current climatic conditions are predicted to become unsuitable in the future (35–38% by 2050 and 2070, respectively), significantly impacting large populations such as those in Romania, Spain, Bulgaria and Hungary. French and Italian populations are identified to be future key populations for Roller conservation.
Our findings suggest that future climate changes will likely amplify the impacts of existing threats on the majority of large European Roller populations in Europe.Solution locale contre menace globale ?
de Elie Gaget, Thomas Galewski
In Espaces naturels, 71 (Juillet-Septembre 2020), 46-47Les oiseaux d'eau en Méditerranée. Mesurer leur réponse au changement climatique
de Elie Gaget, Thomas Galewski
In Courrier de la Nature (Le), 323 (Juillet-Août 2020), 34-39Mediterranean wetland conservation in the context of climate and land cover change
de Roxanne Leberger, Ilse R. Geijzendorffer, Elie Gaget, Anis Guelmami, Thomas Galewski, Henrique M. Pereira, Carlos A. Guerra
In Regional Environmental Change, 20(2) (6/2020), 67
En ligne : link.springer.com[...]
Wetlands are known to support diverse and unique species assemblages. Globally, but particularly in the Mediterranean basin, they are threatened by climate change and natural habitat loss. Despite an alarming decline of wetlands over the last century, standardised and systematic site assessments at large scale do not exist. Here, we perform an integrated assessment of Mediterranean wetlands by evaluating the combination of wetland protection and anthropogenic pressures, namely climate and land cover change, and the subsequent impact on wintering waterbirds. We used a multivariate partial triadic analysis to quantify climate and land cover change for each site between 1990 and 2005. We found that wetland sites in the southeast of the Mediterranean basin combined low or no protection cover with the highest increases in temperature and losses in natural habitats. Despite these findings, these sites also lack observation data on biodiversity, which may underestimate the resulting impacts. However, there are examples where active conservation measurements contributed positively to slow down wetlands’ reduction. Biodiversity data coverage needs to be ensured, regularly updated, and extended across sites regardless of their protection level, to allow for the assessment of biodiversity trends. This should be further extended to include current investments in remote sensing approaches.
de Elie Gaget, I. Le Viol, D. Pavón-Jordán, V. Cazalis, Christian Kerbiriou, Frédéric Jiguet, Nadège Popoff, Laura Dami, Jean-Yves Mondain-Monval, Pierre Defos du Rau, et al.
In Biological Conservation, 243 (March, 2020), 108485
En ligne : www.sciencedirect.com[...]
Although biological conservation is based on international agreements, its effectiveness depends on how countries implement such recommendations as effective conservation tools. The Ramsar Convention is the oldest international treaty for wetland and waterbird conservation, establishing the world's largest network of protected areas. However, since it does not constitute any binding measure, its effectiveness in protecting wintering waterbird populations at an international scale has been questioned. Here, we use long-term (1991–2012) count data to assess the effectiveness of the Ramsar Convention in the Mediterranean Basin. We compared abundance and temporal trends of 114 waterbird species between 251 Ramsar wetlands and 3486 non-Ramsar wetlands. We found that the Ramsar network is critical for wintering waterbirds, concentrating nearly half of all waterbirds counted in the Mediterranean Basin in only 7% of monitored wetlands. Waterbird trends followed a northwest-southeast gradient, with a population decrease in the East. A significant and positive Ramsar effect on population trends was only found for the species of higher conservation concern in the Maghreb, particularly when a management plan was implemented. The Ramsar Convention was previously used on very important wetlands for waterbirds in Southern Europe, but is now an underused conservation tool. Our study suggests weaknesses in the use of Ramsar as an effective conservation tool in most of the Mediterranean Basin. However, the Ramsar Convention effectiveness to enhance waterbird populations in the Maghreb should encourage strengthening the Ramsar Convention. It should be done particularly in countries with limited environmental agreements and by systematic implementation of management plans.
Article impact statement
Identification of the regional disparities in the Ramsar Convention effectiveness to enhance waterbird populations across the Mediterranean Basin.
de Timothée Schwartz
Paris : Université Paris sciences et lettres, 2020, 308
En ligne : www.theses.fr[...]
Les activités humaines sont à l'origine des changements environnementaux actuels et de la crise d'extinction d'espèces qui en découle. Pour y faire face, de nombreuses politiques publiques de protection de la nature ont été mises en place au cours du dernier siècle. L'évaluation environnementale en particulier est apparue dans les années 70 afin de pouvoir éviter, réduire et compenser les impacts des projets de développement et d'infrastructures sur l'environnement, mais les mesures compensatoires qui en découlent font largement appel à l'intervention directe de l'Homme. Au-delà des questions éthiques qu'ils soulèvent, il est possible que les habitats ainsi créés ou restaurés par l'Homme se révèlent défavorables à la survie ou à la reproduction des individus qu'ils attirent, et qu'ils soient donc au final contreproductifs, devenant ce que l'on appelle des pièges écologiques. Ce risque est particulièrement grand pour les dispositifs artificiels, comme les nichoirs et autres gîtes à destination des vertébrés. Vu l'engouement que ces dispositifs suscitent, il est aujourd'hui crucial d'évaluer leur impact réel sur les populations ciblées. Il est aussi urgent de produire des recommandations pour leur utilisation optimale dans une optique de conservation des espèces visées par ces dispositifs. Cette thèse aura donc pour but d'évaluer la pertinence d'un certain nombre de dispositifs artificiels de conservation des vertébrés utilisés actuellement pour la conservation des espèces et notamment dans le cadre de la compensation écologique. Elle s'intéressera en particulier aux gîtes artificiels qui sont très utilisés dans ces contextes. Pour ce faire, nous chercherons tout d'abord à évaluer dans quelle mesure ces dispositifs peuvent constituer des pièges écologiques, en particulier en les comparant à leurs équivalents naturels. Nous comparerons d'une part la dynamique de colonisation et d'abandon entre différents types de sites (artificiels ou non), et d'autre part l'impact de ces dispositifs sur la survie et la reproduction des individus qui les utilisent. Dans un deuxième temps, nous travaillerons à identifier les causes de l'impact négatif de ces dispositifs, le cas échéant, afin de formuler des recommandations de bonnes pratiques pour leur utilisation. Pour cela nous nous intéresserons aux facteurs d'origine humaine : détectabilité des dispositifs, positionnement spatial par rapport aux habitats d'alimentation, caractéristiques physiques et structurelles et microclimat dans les gîtes. Nous étudierons également les stratégies d'évitement des pièges écologiques par les espèces utilisant ces dispositifs et nous mènerons une étude totalement inédite sur l'impact du type de nid sur le microbiote des rolliers. Notre principal modèle d'étude sera le rollier d'Europe Coracias garrulus étudié par l'association A Rocha France depuis plus de quinze ans. Nous nous intéresserons également à trois groupes de vertébrés qui utilisent des dispositifs artificiels : un reptile (le lézard ocellé), un cortège de mammifères (les chauves-souris) et un cortège d'oiseaux d'eau (les laro-limicoles coloniaux).
Estimating biodiversity changes in the Camargue wetlands: An expert knowledge approach
de Sara Fraixedas, Thomas Galewski, Sofia Ribeiro-Lopes, Jonathan Loh, Jacques Blondel, Hugo Fontes, Patrick Grillas, Philippe Lambret, Delphine Nicolas, Anthony Olivier, et al.
In PLOS ONE, 14(10) (24 oct. 2019), e0224235
En ligne : journals.plos.org[...]
Mediterranean wetlands are critical strongholds for biodiversity and the provision of ecosystem functions and services; yet, they are being severely degraded by a number of socio-economic drivers and pressures, including climate change. Moreover, we still lack comprehensive understanding of the extent to which biodiversity loss in Mediterranean wetlands will accelerate change in ecosystem processes. Here, we evaluate how changes in biodiversity can alter the ecosystem of the Camargue (southern France). We collected data on species presence/absence, trends and abundance over a 40-year period by combining observations from the scholarly literature with insights derived from expert knowledge. In total, we gathered more than 1500 estimates of presence/absence, over 1400 estimates of species abundance, and about 1400 estimates of species trends for eight taxonomic groups, i.e. amphibians, reptiles, breeding birds, fish, mammals, dragonflies (odonates), orthopterans and vascular plants. Furthermore, we used information on recently arrived species and invasive species to identify compositional changes across multiple taxa. Complementing targeted literature searches with expert knowledge allowed filling important gaps regarding the status and trends of biodiversity in the Camargue. Species trend data revealed sharp population declines in amphibians, odonates and orthopterans, while birds and plants experienced an average increase in abundance between the 1970s and the 2010s. The general increasing trends of novel and invasive species is suggested as an explanation for the changing abundance of birds and plants. While the observed declines in certain taxa reflect the relative failure of the protection measures established in the Camargue, the increasing exposure to novel and invasive species reveal major changes in the community structure of the different taxonomic groups. This study is the first attempt to assess changes in biodiversity in the Camargue using an expert knowledge approach, and can help manage the uncertainties and complexities associated with rapid social-ecological change in other Mediterranean wetlands.L’état des zones humides dans le monde et en Méditerranée
de Christian Perennou, Laurent Chazee, Thomas Galewski, Ilse Geijzendorffer, Anis Guelmami
In Zones Humides Infos, 97-98 (Eté 2019), 20-21Développement d’un indice en Provence-Alpes-Côte d’Azur
de Thomas Galewski
In Courrier de la Nature (Le), NS (Juillet 2019), 51-53A More Effective Ramsar Convention for the Conservation of Mediterranean Wetlands
de Ilse R. Geijzendorffer, Coralie Beltrame, Laurent Chazee, Elie Gaget, Thomas Galewski, Anis Guelmami, Christian Perennou, Nadège Popoff, Carlos A. Guerra, Roxanne Leberger, et al.
In Frontiers in Ecology and Evolution, 7 (February, 2019)
En ligne : www.frontiersin.org[...]
The Ramsar Convention is the multilateral agreement aimed at protecting wetlands globally. Wetlands are particularly recognized for their role in the Mediterranean biodiversity hotspot by providing key habitats for endemic and migratory species, directly contributing benefits to the lives of people and being an integral part of their culture. In response to this importance, the Mediterranean Wetlands Observatory publishes Mediterranean Wetland Outlooks on the state and trends of Mediterranean wetlands; the first edition in 2012 (MWO1) and the second edition in 2018 (MWO2). In this paper, we used the results of the two Mediterranean Wetland Outlooks to highlight ways to increase the impact of the Ramsar Convention by identifying the spatial dimensions of detected biodiversity trends as well as the societal developments and estimated impacts of global change and protection status.
de Elie Gaget, Thomas Galewski, Frédéric Jiguet, Isabelle Le Viol
In Biological Conservation, 227 (November, 2018), 205-212
En ligne : www.sciencedirect.com[...]
Climate change is one of the strongest biodiversity threats. Worse still, the impact of multiple anthropic stressors on species dynamics could complicate adaptation to temperature increase. International conservation policies aim to protect ecosystems against anthropic pressures, but their ability to facilitate adaptation to climate change has yet to be assessed. Using wetland bird monitoring surveys, we evaluated the differences at the country scale of community adjustment to temperature increase of wintering waterbird communities (145 species) according to the implementation of the two main western Palearctic international conservation policies (Bern Convention and Birds Directive) in the Mediterranean basin (2786 sites, 22 countries) over a 22-year period. We showed that thermic community composition increases over time in countries which have enforced conservation policies. We found that strictly protected species under the Birds Directive and the Bern Convention contributed more to this community adjustment than the not strictly protected species. The mechanism results from a population increase in protected warm-dwelling species but not from a decline in cold-dwelling species. This study supports the ability of international conservation policies to mitigate the effect of climate change on animal communities./
Nous avons observé que les politiques internationales de conservation jouent un rôle positif dans l’adaptation des oiseaux d’eau au réchauffement climatique. Plus les pays du bassin méditerranéen ont des mesures de conservation fortes, plus les changements au sein des communautés d’oiseaux reflètent un meilleur ajustement au réchauffement climatique. Dans le détail, les espèces strictement protégées par la Directive Oiseaux et la Convention de Berne ont un meilleur ajustement de leur distribution que les espèces non strictement protégées.Context-dependent conservation of the cavity-nesting European Roller
de Tom Finch, Claire Branston, Harriet Clewlow, Jamie Dunning, Aldina M. A. Franco, Edmunds Račinskis, Timothée Schwartz, Simon J. Butler
In Ibis, 161(3) (July 2018), 1-17
En ligne : onlinelibrary.wiley.com[...]
To maximize the effectiveness of conservation interventions, it is crucial to have an understanding of how intraspecific variation determines the relative importance of potential limiting factors. For bird populations, limiting factors include nest-site availability and foraging resources, with the former often addressed through the provision of artificial nestboxes. However, the effectiveness of artificial nestboxes depends on the relative importance of nest-site vs. foraging resource limitations. Here, we investigate factors driving variation in breeding density, nestbox occupation and productivity in two contrasting study populations of the European Roller Coracias garrulus, an obligate cavity-nesting insectivorous bird. Breeding density was more than four times higher at the French study site than at the Latvian site, and there was a positive correlation between breeding density (at the 1-km2 scale) and nest-site availability in France, whereas there was a positive correlation between breeding density and foraging resource availability in Latvia. Similarly, the probability of a nestbox being occupied increased with predicted foraging resource availability in Latvia but not in France. We detected no positive effect of foraging resource availability on productivity at either site, with most variation in breeding success driven by temporal effects: a seasonal decline in France and strong interannual fluctuations in Latvia. Our results indicate that the factors limiting local breeding density can vary across a species' range, resulting in different conservation priorities. Nestbox provisioning is a sufficient short-term conservation solution at our French study site, where foraging resources are typically abundant, but in Latvia the restoration of foraging habitat may be more important.
de Thomas Galewski, Vincent Devictor
In PLOS ONE, 11 (Nov. 2016), 1-18
En ligne : journals.plos.org[...]
Many species have suffered large population declines due to the anthropogenic influence on ecosystems. Understanding historical population trends is essential for informing best efforts to preserve species. We propose a new method to reconstruct the past structure of a regional species pool, based on historical naturalist literature. Qualitative information collected from annotated checklists and reports can be relevant to identify major long-term community changes. We reviewed ornithological literature on the Camargue, the largest wetland in France. We reconstructed the entire breeding bird community from 1830 to 2009 and translated historical data into semi-quantitative data. This data permitted a calculation of a Community Commonness Index to measure the average level of abundance of species in a community. The Community Specialization and Community Temperature Indices were used to evaluate the potential long-term impact of land-use and climate changes on the composition of the regional bird species pool. We found a decrease in average abundance and specialization between 1950 and 1989, suggesting that changes in land-use negatively impacted the structure and composition of the local bird community by reducing species abundance and removing habitat-specialists (e.g. Southern Grey Shrike, Greater Short-toed Lark). These results are likely to be linked with a major loss of natural habitats in the Camargue between 1942 and 1984 when natural areas and traditional farmland were converted into intensive cultivated lands. We also found fluctuations among species with high versus low temperature preference. However, long-term effects of climate change on the bird community might be blurred by the impact of land-use changes. Overall, our results contrast with those obtained from well-monitored colonial waterbirds showing long-term increases. Our results plead for a more regular use of historical naturalist data when examining long-term changes in species communities as they allow the establishment of an older temporal point of reference and consideration of species not covered by traditional monitoring schemes. / où l’on présente l’intérêt de la littérature « grise » naturaliste (livres, compte-rendus, rapports de voyage…) pour retracer les variations démographiques historiques d’une population, d’une espèce ou d’une communauté d’espèces.
Ici on s’est intéressé à la communauté d’oiseaux nicheurs de Camargue que l’on a pu reconstruire depuis le début du 19ème siècle jusqu’à nos jours. Il a été possible de coder de manière semi-quantitative l’abondance de toutes les espèces à différents pas de temps. En utilisant cette méthodologie, on observe que la communauté a beaucoup évolué dans le temps avec notamment une diminution de l’abondance spécifique et une perte de spécialisation. En d’autres termes, si 2 espèces sur 3 pouvaient être qualifiées de communes au 19ème siècle, ce n’est plus le cas que pour 1 espèce sur 3 aujourd’hui. La diminution a principalement affecté les espèces spécialistes des milieux agricoles et pâturés (ex : Alouettes, Perdrix rouge, Chevêche, Petit-duc, Tourterelle des bois, Linotte et beaucoup d’autres) tandis que les oiseaux utilisant les milieux humides ont mieux résisté. Ce déclin s’est produit dans les années 1950-1980 à une époque où on enregistre une très forte perte de milieux naturels et semi-naturels en Camargue (pelouses et sansouires en premier lieu) ainsi qu’un changement majeur de l’agriculture camarguaise qui délaisse l’élevage extensif au profit d’une céréaliculture intensive. Cette étude met en évidence un déclin important des oiseaux des milieux agricoles bien antérieur et supérieur au déclin observé depuis 20 ans à travers les programmes de science citoyenne
de Thomas Galewski, Ben Collen, Louise McRae, Jonathan Loh, Patrick Grillas, Michel Gauthier-Clerc, Vincent Devictor
In Biological Conservation, 144(5) (MAY 2011), 1392-1399
Biodiversity loss is unevenly distributed in space and time. Species have reached critically low population sizes in some areas, and remain abundant in others. Similarly, some species may benefit from successful conservation plans, while others still experience severe population depletions driven by negative impacts of human activities. Although several indicators have been proposed to measure the fate of biodiversity, they are generally only implemented globally so their relevance for regional assessment is still unclear. Here, we calculated the first regional trend in the Living Planet Index for the Mediterranean wetlands (Med LPI), an indicator that summarizes the fate of global biological diversity based on the temporal trends in abundance of vertebrate populations. The Med LPI was based on 1641 vertebrate populations of 311 species recorded in Mediterranean wetlands from 1970-2008, in 27 different countries. We investigated whether trends in the Med LPI differed between eastern and western Mediterranean countries, which have different socio-economic contexts. Finally, we assessed whether and how the trend in the Med LPI was robust to changes in the number and identity of species considered. We found that, at the Mediterranean scale, the Med LPI increased steeply, which could be taken at first sight, as a general recovery of wetland biodiversity in this biogeographical region. However, we found highly contrasting spatial trends within the Mediterranean region: the average trend was positive for western and negative for eastern countries. Moreover, we showed that depending on the method used to estimate the trend in Med LPI, it can be sensitive to the number and identity of the species considered. We suggest that understanding the regional discrepancies of the trend in biodiversity indicators as well as their robustness to the species represented in the index will enhance progress assessment towards global and regional conservation strategies. (C) 2011 Elsevier Ltd. All rights reserved.Des marais au pays du matin calme? (2008)
de G. Barnaud, Thomas Galewski
2008MedWet: l'observatoire des zones humides méditerranéennes au service d'une nouvelle stratégie (2008)
de Jean Jalbert, Thomas Galewski
2008
