Les articles de Thomas Blanchon

Spatiotemporal Dynamics of Blood Parasite Infections and Impacts on Avian Health and Reproduction

Wed, 3 Dec 2025 11:08:08

de Marie Buysse, Mathilde Ollagnier, Charly Souc, Marjorie Bruley, Thomas Blanchon, Carole Leray, Marion Vittecoq, Karen D. McCoy
In Molecular Ecology, (en ligne) (December, 2025), e70178
En ligne : onlinelibrary.wiley.com[...]

Parasitic infections are ubiquitous in nature, but their consequences are often difficult to evaluate in wildlife. This is particularly the case for chronic infections for which fitness impacts can be subtle or confounded with other intrinsic and extrinsic factors. Infections by Babesia (Apicomplexa, Piroplasmidae) are widespread in wildlife, but little is known about their impacts on host health. Here, we evaluated the dynamics and possible fitness consequences of infection by Babesia sp. YLG, a recently described parasite infecting yellow-legged gulls (Larus michahellis). Using a qPCR assay developed for Babesia sp. YLG, we found that prevalence was much higher in chicks compared with adults. In chicks, infection depended on the colony and was tightly related to nest infestation by the tick vector Ornithodoros (Alectorobius) maritimus; this was not the case for adult birds. Infection intensities changed over time in chicks, increasing up to approximately 37 days old and then declining. Infection was associated with reduced body condition and fledging success for adults. In chicks, infection was significantly linked to reduced growth rates, even after accounting for the additive effect of ticks. However, no relationship was detected between infection and fledging date, migration strategy or flight distances measured on a subset of GPS-tagged juvenile birds. Through its subtle effects on fitness and reproductive success, infection by Babesia sp. YLG may have significant consequences for host demography and work focused on long-term dynamics is now called for to better understand how this parasite may shape the ecology and evolution of seabird populations.

Évolution des effectifs nicheurs des ardéidés coloniaux arboricoles et paludicoles en Camargue et sur la façade méditerranéenne française

Wed, 22 Oct 2025 15:17:45

de Yves Kayser, Thomas Blanchon, Antoine Arnaud, Olivier Pineau, Michel Gauthier-Clerc, Jean-Laurent Lucchesi, Gregoire Massez, Christophe Pin, Clément Pappalardo, Jérémiah Petit, et al.
In Ornithos, 172 (Juillet, août, septembre 2025), 16-33

Les suivis des populations reproductrices d’ardéidés coloniaux sont réalisés chaque année sur la bordure méditerranéenne française depuis 1968 pour les hérons paludicoles ainsi qu’en Camargue depuis 1969 pour les espèces arboricoles. Neuf espèces de hérons se reproduisent dans cette région dont sept sont concernées par ces recensements : le Bihoreau gris Nycticorax nycticorax, le Crabier chevelu Ardeola ralloides, le Héron garde-bœufs Ardea ibis, le Héron cendré Ardea cinerea, le Héron pourpré Ardea purpurea, la Grande Aigrette Ardea alba et l’Aigrette garzette Egretta garzetta.

Do older parents do better? Relationships between parental age, chick body condition and migratory behaviour in a colonial-breeding waterbird

Wed, 18 Jun 2025 15:13:45

de Hugo R. S. Ferreira, Jocelyn Champagnon, Thomas Blanchon, Tamar Lok, José A. Alves
In Journal of Avian Biology, 2025(3) (May, 2025), e03387
En ligne : onlinelibrary.wiley.com[...]

Animals' performance of basic functional behaviours, such as foraging and movement, may improve with age as a result of past experiences. In migratory birds, for example, due to earlier or more efficient migration, older and likely more experienced individuals tend to arrive at breeding sites earlier and enjoy better breeding conditions than younger conspecifics, resulting in a higher reproductive success. Yet, despite the advantages of early arrival for breeding adults, the long-term effects of fledging early and/or with a higher body condition on chicks' future fitness prospects remain largely unexplored. In differential migration systems, low-quality or socially subordinate individuals may be constrained to sub-optimal migratory behaviours associated with lower demographic rates. Therefore, producing high-quality chicks may enhance the survival of offspring. In this study, we analysed data from the long-term ringing programme on the breeding population of Eurasian spoonbills in the Camargue (southern France) to investigate how breeder age may influence the timing of breeding and, in turn, how this may affect chick body condition and their subsequent migratory behaviour. Using breeding resightings of birds individually marked as a chick since 2008, combined with chick biometric measurements and subsequent winter resightings of offspring, we show that older spoonbills tend to breed earlier in the season than younger individuals, and that early breeders, regardless of age, are more likely to produce chicks with higher body condition than late breeders. Finally, migratory behaviour of juveniles appears to be influenced by the timing of breeding, with later-born juveniles tending to undertake less demanding migrations (without crossing major ecological barriers) than juveniles born earlier in the breeding season. Our study therefore highlights the relevance of long-term studies to better understand the complex breeding phenology of migratory species, which can lead to changes in population-level patterns and processes.

Role of protected areas for a colonial-breeding waterbird in a fragmented landscape throughout its annual cycle

Mon, 6 Jan 2025 15:32:43

de Hugo Rafael Soares Ferreira, José A. Alves, Frédéric Jiguet, Olivier Duriez, Thomas Blanchon, Tamar Lok, Jocelyn Champagnon
In Landscape Ecology, 40(1) (December, 2024), 6
En ligne : doi.org[...]

Throughout their annual cycle and life stages, animals depend on a variety of habitats to meet their vital needs. However, habitat loss, degradation, and fragmentation are making it increasingly difficult for mobile species such as birds to find suitable habitats. Wetlands are highly productive systems of great importance to many animals, but their continued degradation threatens their capacity to support different species, including waterbirds. In this context, waterbirds are likely to benefit not only from the creation and management of protected wetlands, but also from the existence of anthropogenic wetlands, managed for economic or recreational activities.
/ Cette étude explore comment la spatule, une espèce modérément spécialisée, bénéficie des changements globaux actuels grâce à sa capacité à exploiter des habitats appropriés, qu’ils soient naturels ou artificiels, au sein de paysages fragmentés. Cependant, sa dépendance aux zones humides gérées par le secteur privé soulève des questions importantes, car elle peut avoir de lourdes conséquences pour les espèces fortement tributaires de ces habitats. Ainsi, promouvoir la gestion des habitats favorisant des conditions naturelles apparaît crucial pour préserver la résilience des espèces.
Comprendre comment des actions de gestion spécifiques influencent la présence des oiseaux d’eau et l’utilisation de leur habitat est essentiel non seulement pour accroître l’efficacité des efforts de conservation, mais aussi pour renforcer la connectivité des zones humides et la résilience des espèces, en particulier dans des paysages fragmentés.

La Spatule blanche Platalea leucorodia en Dombes : origine, déplacements, place dans le contexte ouest-européen

Mon, 16 Sep 2024 16:18:41

de Maurice Benmergui, Marine Galy, Thomas Blanchon, Jocelyn Champagnon, Lok Tamar, Stefano Volponi
In Alauda, 92(3) (Septembre, 2024), 203-224

La Spatule blanche se reproduit depuis 2006 dans Ia Dombes, région composée de plus de 1 300 étangs piscicoles extensifs situés à quelques dizaines de kilomètres de l’agglomération lyonnaise. Sa population est l’une des plus petites et des plus fragiles de France, car soumise a l’aléa d’un système particulier d’exploitation des étangs, d’assèchement (a assec ii) et de drainage estival, qui semble compromettre Ia stabilité des colonies. La Dombes est historiquement Ia première et reste l’une des régions les plus continentales où se reproduit Ia Spatule blanche en France : le littoral le plus proche est celui de Ia Méditerranée, avec Ia Camargue, située à environ 300 km au Sud. Depuis 1991, cette espèce est baguée dans le cadre de plusieurs programmes européens de conservation. Plusieurs de ces oiseaux bagués fréquentent Ia Dombes. A partir des observations réalisées d’après 53 individus, entre 1991 et 2020, nous tentons de remonter aux origines géographiques des individus présents en Dombes. Les résultats révèlent, que les oiseaux contrôlés et bagués au nid proviennent de Camargue (67,9 %), des Pays-Bas (11,3 %), d’Italie (9,4 %), de Croatie (3,8 %), d’Allemagne (3,8 %) et de Belgique (1,9 %). Hormis Ia France, 13 pays accueillent des spatules en escale : l’Espagne (28,3 %); les Pays-Bas (20,8 %); l’Allemagne (9,4 %); l’Italie, Ia Belgique et la Mauritanie (7,5 % chacun); le Maroc (5,7 %); le Portugal et la Tunisie (3,8 % chacun); Ia Suisse, l’Autriche, le Sénégal et l’Algérie (1,9 % chacun). Les étapes migratoires correspondent globalement à celles des oiseaux camarguais qui empruntent Ia route côtière pour rejoindre I ’Espagne, le Maroc et le Banc d’Arguin mauritanien pour y hiverner. L’âge de première visite des Spatules en Dombes est dominé par Ia classe des oiseaux de 3-4 ans (39,6 %), puis celle des 5-6 ans (24,5 %). La durée minimale de séjour postnuptial est de 33 jours mais reste variable et 26 % des spatules restent plus de deux mois. Bien que marginales par rapport au nombre élevé d’oiseaux bagués en Europe du Nord, en Camargue, en Italie ou en Croatie, les contrôles réalisés dans Ia Dombes démontrent de possibles échanges entre : ces populations. Celle de Ia Dombes apparait, comme celle de Camargue, comme une population d’origine mixte, issue du groupe Mer du Nord-Atlantique d’une part et, du groupe Méditerranée Centrale d’autre part (Champagnon et al., 2019). Les oiseaux italiens et croates quant à eux appartiennent au groupe de Ia Méditerranée centrale, mais leur présence dans Ia Dombes, fortuite, témoigne d’une certaine fidélité à Ia région tant en migration qu’en période de reproduction. A ce jour, seuls deux oiseaux d’origine camarguaise sont nicheurs dans les colonies de Ia Dombes confirmant l’influence de Ia population camarguaise sur celle reproductrice de Ia Dombes. Un autre événement original est Ia dispersion postnuptiale d’une fraction des oiseaux camarguais vers les étangs de Ia Dombes et qui peut atteindre ponctuellement 200 à 300 individus. Nous discutons l’intérêt pour Ia Dombes de rejoindre les régions et pays réunis sur Ia question de Ia conservation de l’espèce dans un contexte climatique pouvant fragiliser notamment certaines populations littorales, ainsi que d’affirmer l’importance écologique et régionale de Ia biodiversité d’une région qui vient d’être désignée parmi les 18 zones humides emblématiques de France dans le nouveau Plan d’Action Zones Humides 2022-2026.

No detrimental effects of wing-harnessed GPS devices on the breeding performance of Yellow-legged Gulls (Larus michahellis): A multi-colony evaluation

Wed, 26 Jun 2024 16:19:01

de Charly Souc, Carole Leray, Thomas Blanchon, Thomas Dagonet, Marion Vittecoq, Raul Ramos, Karen D. McCoy
In Ibis, (en ligne) (June, 2024)
En ligne : onlinelibrary.wiley.com[...]

A recent study revealed that wing-harnessed tracking devices negatively affected reproductive success of Great Black-backed Gulls Larus marinus. To evaluate the generality of this effect in large gulls, we investigated the reproductive performance associated with the same type of GPS-mounted system in four Mediterranean breeding colonies of the Yellow-legged Gull Larus michahellis in 2022. We found no significant difference in reproductive parameters among adults handled with a mounted device, adults handled with no device, and controls, and no interaction with colony of origin. The impact of the GPS harness system on short-term reproduction is therefore not generalizable among larid species, and should be tested and reported whenever a new tracking programme is employed.

Dynamique très positive pour les laro-limicoles coloniaux méditerranéens de 2011 à 2021

Thu, 11 Jul 2024 11:57:39

de Olivier Scher, Arnaud Béchet, Christophe Pin, Thomas Blanchon, Elvin Miller, Florian Escot, Rémi Tiné, Rémi Jullian, Florian Ollivier, Dominique Clément, et al.
In Ornithos, 31(3) (Mai-Juin, 2024), 113-137

Huit espèces de laridés et de limicoles nicheurs se rencontrent le long du littoral sableux de la cóte méditerranéenne française continentale. Leur écologie est variée mais, dans Ia mesure où ils nichent en colonies mono- ou plurispécifiques sur des îlots, ils sont confrontés aux mêmes problématiques de conservation durant la saison de reproduction. Ces espèces, que nous nommons ici par convenance "laro limicoles coloniaux", rassemblent le Goéland railleur Chroicocephalus genei, la Mouette rieuse C. ridibundus, la Mouette mélanocéphale lchthyaetus melanocephalus, les Sternes pierregarin Sterna hirundo, naine Sternula albifrons, caugek Thalasseus sandyicensis, hansel Gelochelidon nilotica et l’Avocette élégante Recurvirostra avosetta. A l'exception de la Mouette rieuse, toutes sont inscrites à l’annexe I de Ia Directive Oiseaux, parmi lesquelles deux — le Goéland railleur et la Sterne hansel — ont un statut "Vulnerable" sur la liste rouge de l'UICN à l'échelle nationale. Compte tenu de l’abondance de ces oiseaux sur leur façade méditerranéenne, les régions Occitanie et Provence-Alpes-Cóte-d’Azur ont une responsabilité particulière pour leur conservation.

Compte rendu ornithologique : Camargue, Crau, Alpilles, pour les années 2013 à 2018

Fri, 8 Mar 2024 16:35:40

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.

Natal colony influences age-specific movement patterns of the Yellow-legged gull (Larus michahellis)

Tue, 24 Oct 2023 18:08:30

de Charly Souc, Nicolas Sadoul, Thomas Blanchon, Marion Vittecoq, Christophe Pin, Eric Vidal, Alain Mante, Remi Choquet, Karen D. McCoy
In Movement Ecology, 11(1) (August, 2023), 11
En ligne : doi.org[...]

As for other life history traits, variation occurs in movement patterns with important impacts on population demography and community interactions. Individuals can show variation in the extent of seasonal movement (or migration) or can change migratory routes among years. Internal factors, such as age or body condition, may strongly influence changes in movement patterns. Indeed, young individuals often tend to move across larger spatial scales compared to adults, but relatively few studies have investigated the proximate and ultimate factors driving such variation. This is particularly the case for seabirds in which the sub-adult period is long and difficult to follow. Here, we examine migration variation and the factors that affect it in a common Mediterranean seabird, the Yellow-legged gull (Larus michahellis).

Field margins as substitute habitat for the conservation of birds in agricultural wetlands

Mon, 21 Aug 2023 15:21:50

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.

Antimicrobial-Resistant Bacteria Carriage in Rodents According to Habitat Anthropization

Thu, 15 Jun 2023 16:17:49

de Marion Vittecoq, Eric Elguero, Lionel Brazier, Nicolas Renaud, Thomas Blanchon, François Roux, François Renaud, Patrick Durand, Frederic Thomas
In EcoHealth, 20 (May, 2023)
En ligne : doi.org[...]

It is increasingly suggested that the dynamics of antimicrobial-resistant bacteria in the wild are mostly anthropogenically driven, but the spatial and temporal scales at which these phenomena occur in landscapes are only partially understood. Here, we explore this topic by studying antimicrobial resistance in the commensal bacteria from micromammals sampled at 12 sites from a large heterogenous landscape (the Carmargue area, Rhone Delta) along a gradient of anthropization: natural reserves, rural areas, towns, and sewage-water treatment plants. There was a positive relationship between the frequency of antimicrobial-resistant bacteria and the level of habitat anthropization. Although low, antimicrobial resistance was also present in natural reserves, even in the oldest one, founded in 1954. This study is one of the first to support the idea that rodents in human-altered habitats are important components of the environmental pool of resistance to clinically relevant antimicrobials and also that a “One Health” approach is required to assess issues related to antimicrobial resistance dynamics in anthropized landscapes.

Efficacy of created and restored nesting sites for the conservation of colonial Laridae in the south of France

Thu, 6 Oct 2022 10:32:17

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.

Multiresistant Enterobacteriaceae in yellow-legged gull chicks in their first weeks of life

Fri, 17 Jun 2022 12:21:51

de Marion Vittecoq, Lionel Brazier, Eric Elguero, Ignacio G. Bravo, Nicolas Renaud, Alejandro Manzano-Marín, Franck Prugnolle, Sylvain Godreuil, Thomas Blanchon, François Roux, et al.
In Ecology and Evolution, 12(6) (June, 2022), 10
En ligne : onlinelibrary.wiley.com[...]

Wild animal species living in anthropogenic areas are commonly carriers of antimicrobial-resistant bacteria (AMRB), but their role in the epidemiology of these bacteria is unclear. Several studies on AMRB in wildlife have been cross-sectional in design and sampled individual animals at only one point in time. To further understand the role of wildlife in maintaining and potentially transmitting these bacteria to humans and livestock, longitudinal studies are needed in which samples are collected from individual animals over multiple time periods. In Europe, free-ranging yellow-legged gulls (Larus michahellis) commonly live in industrialized areas, forage in landfills, and have been found to carry AMRB in their feces. Using bacterial metagenomics and antimicrobial resistance characterization, we investigated the spatial and temporal patterns of AMRB in a nesting colony of yellow-legged gulls from an industrialized area in southern France. We collected 54 cloacal swabs from 31 yellow-legged gull chicks in 20 nests on three dates in 2016. We found that AMRB in chicks increased over time and was not spatially structured within the gull colony. This study highlights the complex occurrence of AMRB in a free-ranging wildlife species and contributes to our understanding of the public health risks and implications associated with ARMB-carrying gulls living in anthropogenic areas.

Genetic diversity and relationships of the liver fluke Fasciola hepatica (Trematoda) with native and introduced definitive and intermediate hosts

Wed, 4 Nov 2020 13:41:51

de Antonio A. Vázquez, Emeline Sabourin, Pilar Alda, Clémentine Leroy, Carole Leray, Eric Carron, Stephen Mulero, Céline Caty, Sarah Hasfia, Michel Boisseau, et al.
In Transboundary and Emerging Diseases, 68(4) (November, 2020)
En ligne : onlinelibrary.wiley.com[...]

Fasciolosis is a worldwide spread parasitosis mainly caused by the trematode Fasciola hepatica. This disease is particularly important for public health in tropical regions, but it can also affect the economies of many developed countries due to large infections in domestic animals. Although several studies have tried to understand the transmission by studying the prevalence of different host species, only a few have used population genetic approaches to understand the links between domestic and wildlife infections. Here, we present the results of such genetic approach combined with classical parasitological data (prevalence and intensity) by studying domestic and wild definitive hosts from Camargue (southern France) where fasciolosis is considered as a problem. We found 60% of domestic hosts (cattle) infected with F. hepatica but lower values in wild hosts (nutria, 19%; wild boars, 4.5%). We explored nine variable microsatellite loci for 1,148 adult flukes recovered from four different populations (non-treated cattle, treated cattle, nutria and wild boars). Populations from the four groups differed, though we found a number of migrants particularly non-treated cattle and nutria. Overall, we detected 729 different multilocus genotypes (from 783 completely genotyped individuals) and only 46 genotypes repeated across samples. Finally, we experimentally infected native and introduced intermediate snail hosts to explore their compatibility with F. hepatica and assess the risks of fasciolosis expansion in the region. The introduced species Galba truncatula and Pseudosuccinea columella attained the higher values of overall compatibility in relation to the European species. However, concerning the origin, sympatric combinations of G. truncatula were more compatible (higher prevalence, intensity and survival) than the allopatric tested. According to our results, we should note that the assessment of epidemiological risks cannot be limited to a single host–parasite system, but should focus on understanding the diversity of hosts in the heterogeneous environment through space and time.

Evaluating Functional Dispersal in a Nest Ectoparasite and Its Eco-Epidemiological Implications

Mon, 25 Oct 2021 14:36:36

de Amalia Rataud, Marlene Dupraz, Céline Toty, Thomas Blanchon, Marion Vittecoq, Remi Choquet, Karen D. McCoy
In Frontiers in Veterinary Science, 7 (October, 2020), 722
En ligne : www.frontiersin.org[...]

Functional dispersal (between-site movement, with or without subsequent reproduction) is a key trait acting on the ecological and evolutionary trajectories of a species, with potential cascading effects on other members of the local community. It is often difficult to quantify, and particularly so for small organisms such as parasites. Understanding this life history trait can help us identify the drivers of population dynamics and, in the case of vectors, the circulation of associated infectious agents. In the present study, functional dispersal of the soft tick Ornithodoros maritimus was studied at a small scale, within a colony of yellow-legged gulls (Larus michahellis). Previous work showed a random distribution of infectious agents in this tick at the within-colony scale, suggesting frequent tick movement among nests. This observation contrasts with the presumed strong endophilic nature described for this tick group. By combining an experimental field study, where both nest success and tick origin were manipulated, with Capture-Mark-Recapture modeling, dispersal rates between nests were estimated taking into account tick capture probability and survival, and considering an effect of tick sex. As expected, tick survival probability was higher in successful nests, where hosts were readily available for the blood meal, than in unsuccessful nests, but capture probability was lower. Dispersal was low overall, regardless of nest state or tick sex, and there was no evidence for tick homing behavior; ticks from foreign nests did not disperse more than ticks in their nest of origin. These results confirm the strong endophilic nature of this tick species, highlighting the importance of life cycle plasticity for adjusting to changes in host availability. However, results also raise questions with respect to the previously described within-colony distribution of infectious agents in ticks, suggesting that tick dispersal either occurs over longer temporal scales and/or that transient host movements outside the breeding period result in vector exposure to a diverse range of infectious agents.

Changes in Bacterial Diversity, Composition and Interactions During the Development of the Seabird Tick Ornithodoros maritimus (Argasidae)

Tue, 13 Oct 2020 18:11:39

de Yann Gomard, Olivier Flores, Marion Vittecoq, Thomas Blanchon, Céline Toty, Olivier Duron, Patrick Mavingui, Pablo Tortosa, Karen D. McCoy
In Microbial Ecology, Online (October, 2020)
En ligne : doi.org[...]

Characterising within-host microbial interactions is essential to understand the drivers that shape these interactions and their consequences for host ecology and evolution. Here, we examined the bacterial microbiota hosted by the seabird soft tick Ornithodoros maritimus (Argasidae) in order to uncover bacterial interactions within ticks and how these interactions change over tick development. Bacterial communities were characterised through next-generation sequencing of the V3–V4 hypervariable region of the bacterial 16S ribosomal RNA gene. Bacterial co-occurrence and co-exclusion were determined by analysing networks generated from the metagenomic data obtained at each life stage. Overall, the microbiota of O. maritimus was dominated by four bacterial genera, namely Coxiella, Rickettsia, Brevibacterium and Arsenophonus, representing almost 60% of the reads. Bacterial diversity increased over tick development, and adult male ticks showed higher diversity than did adult female ticks. Bacterial networks showed that co-occurrence was more frequent than co-exclusion and highlighted substantial shifts across tick life stages; interaction networks changed from one stage to the next with a steady increase in the number of interactions through development. Although many bacterial interactions appeared unstable across life stages, some were maintained throughout development and were found in both sexes, such as Coxiella and Arsenophonus. Our data support the existence of a few stable interactions in O. maritimus ticks, on top of which bacterial taxa accumulate from hosts and/or the environment during development. We propose that stable associations delineate core microbial interactions, which are likely to be responsible for key biological functions.

Foraging niche shift maintains breeding parameters of a colonial waterbird during range expansion

Fri, 14 Feb 2020 14:26:55

de Charlotte Francesiaz, Elizabeth Yohannes, Aurélien Besnard, Nicolas Sadoul, Thomas Blanchon, Arnaud Béchet
In Ecology and Evolution, 10(4) (February, 2020), ece3.6030
En ligne : onlinelibrary.wiley.com[...]

Relating the effects of foraging niche variation to reproductive dynamics is critical to understand species response to environmental change. We examined foraging niche variations of the slender-billed gull (Chroicocephalus genei), a nomadic colonial waterbird species during its range expansion along the French Mediterranean coast over a 16-year period (1998–2013). We investigated whether range expansion was associated with a change in chick diet, breeding success, and chicks body condition. We also examined whether breeding success and chicks body condition were explained by diet and colonial characteristics (number of pairs, laying phenology, habitat, and locality). Diet was characterized using dual-stable isotopic proxies (δ13C and δ15N) of feather keratin from 331 individuals subsampled from a total of 4,154 chicks ringed and measured at 18 different colonies. δ13C decreased and δ15N increased significantly during range expansion suggesting that chicks were fed from preys of increasing trophic level found in the less salty habitat colonized by the end of the study period. Niche shift occurred without significant change of niche width which did not vary among periods, habitats, or localities either. Breeding success and chick body condition showed no consistent trends over years. Breeding success tended to increase with decreasing δ13C at the colony level while there was no relationship between stable isotope signatures and chick body condition. Overall, our results suggest that even if range expansion is associated with foraging niche shift toward the colonization of less salty and more brackish habitats, the shift had marginal effect on the breeding parameters of the Slender-billed gull. Niche width appears as an asset of this species, which likely explains its ability to rapidly colonize new locations.

The Settlement of Glossy Ibis in France

Fri, 29 Nov 2019 16:04:13

de Jocelyn Champagnon, Yves Kayser, Jérémiah Petit, Loïc Marion, Sebastien Reeber, Thomas Blanchon, Samuel Hilaire, Irene Badone, Pierre Crouzier, Regis Purenne, et al.
In SIS Conservation, 1 (December, 2019), 50-55
En ligne : storkibisspoonbill.org[...]

The Glossy Ibis Plegadis falcinellus was very rarely breeding in France until its settlement in Camargue in 2006, in a colony of ardeids. From then, the number of breeding pairs increased exponentially to reach 2,087 breeding pairs in 2017 distributed over ten colonies mainly in Camargue but also in others sites over the French Mediterranean coast. In parallel, breeding attempts occurred regularly in other regions, with some successes in Loire Atlantic on the Atlantic coast. Here we present some preliminary results on the ringing programme of chicks conducted in Camargue since 2006 and on the diet of the breeding birds. Finally, we discuss factors that influence the settlement of new colonies.

Evaluating functional dispersal and its eco-epidemiological implications in a nest ectoparasite

Thu, 14 Mar 2019 14:24:42

de Amalia Rataud, Marlene Dupraz, Céline Toty, Thomas Blanchon, Marion Vittecoq, Remi Choquet, Karen D. McCoy
In Zenodon, reviewed and recommended by Peer Community In Ecology, 10.5281/zenodo.2573075 (March, 2019), 18
En ligne : zenodo.org[...]

Functional dispersal (between-site movement, with or without subsequent reproduction) is a key trait acting on the ecological and evolutionary trajectories of a species, with potential cascading effects on other members of the local community. It is often difficult to quantify, and particularly so for small organisms such as parasites. Understanding this life history trait can help us identify the drivers of population dynamics and, in the case of vectors, the circulation of associated infectious agents. In the present study, functional dispersal of the soft tick Ornithodoros maritimus was studied at small scale, within a colony of yellow-legged-gulls (Larus michahellis). Previous work showed a random distribution of infectious agents in this tick at the within-colony scale, suggesting frequent tick movement among nests. This observation contrasts with the presumed strong endophilic nature described for this tick group. By combining an experimental field study, where both nest success and tick origin were manipulated, with Capture-Mark-Recapture modeling, dispersal rates between nests were estimated taking into account both tick capture probability and survival, and considering an effect of tick sex. As expected, tick survival probability was higher in successful nests, where hosts were readily available for the blood meal, than in unsuccessful nests, but capture probability was lower. Dispersal was low overall, regardless of nest state or tick sex, and there was no evidence for tick homing behavior; ticks from foreign nests did not disperse more than ticks in their nest of origin. These results confirm the strong endophilic nature of this tick species, highlighting the importance of life cycle plasticity for adjusting to changes in host availability. However, results also raise questions with respect to the previously described within-colony distribution of infectious agents in ticks, suggesting that tick dispersal either occurs over longer temporal scales and/or that transient host movements outside the breeding period result in vector exposure to a diverse range of infectious agents.

L’hivernage de la Grue cendrée Grus grus en Camargue : historique et statut récent

Tue, 12 Jun 2018 12:09:19

de Yves Kayser, Michel Gauthier-Clerc, Thomas Blanchon, Philippe Vandewalle, Silke Befeld, Jérémiah Petit, Rémi Tiné, Amine Flitti, Jocelyn Champagnon
In Ornithos, 25(1) (2018), 4-13

The Common Crane was a rare wintering bird in The Camargue until the late 1990s and early 2000s. From the winter of 2003- 2004, wintering numbers have steadily increased to more than 14,000 individuals by January 2017, spread over a dozen roosts. The frequented roosts are large open areas, usually made up of freshwater marshes. During the winter season, cranes mainly feed on rice stubble. Other food resources such as winter wheat are used to a lesser extent. Some birds do not hesitate to fly further up to 30 km to fetch food. Fifty ringed birds were controlled between 2013 and 2017, the majority (89 %) of them originated from Finland. It seems that the cranes use two migration routes to The Camargue : one central European routeway and another one possibly passing through western France, which could indicate a loop migration.

Trois spatules blanches Platalea leucorodia nées en Camargue (Bouches-du-Rhône) contrôlées en hivernage au Soudan du Sud

Thu, 5 Oct 2017 14:47:34

de Thomas Blanchon, Jocelyn Champagnon, Yves Kayser, Lina Lopez-Ricaurte, Paul Isenmann
In Alauda, 85(3) (oct 2017), 231-233

Population structure of the soft tick Ornithodoros maritimus and its associated infectious agents within a colony of its seabird host Larus michahellis

Fri, 11 Aug 2017 09:18:28

de Marlene Dupraz, Céline Toty, Elodie Devillers, Thomas Blanchon, Eric Elguero, Marion Vittecoq, Sara Moutailler, Karen D. McCoy
In International Journal for Parasitology: Parasites and Wildlife, 6(2) (08/2017), 122-130
En ligne : www.sciencedirect.com[...]

The epidemiology of vector-borne zoonoses depends on the movement of both hosts and vectors, which can differ greatly in intensity across spatial scales. Because of their life history traits and small size, vector dispersal may be frequent, but limited in distance. However, little information is available on vector movement patterns at local spatial scales, and particularly for ticks, transmitting the greatest diversity of recognized infectious agents. To test the degree to which ticks can disperse and disseminate pathogens at local scales, we investigated the temporal dynamics and population structure of the soft tick Ornithodoros maritimus within a colony of its seabird host, the Yellow-legged gull Larus michahellis. Ticks were repeatedly sampled at a series of nests during the host breeding season. In half of the nests, ticks were collected (removal sampling), in the other half, ticks were counted and returned to the nest. A subsample of ticks was screened for known bacteria, viruses and parasites using a high throughput real-time PCR system to examine their distribution within the colony. The results indicate a temporal dynamic in the presence of tick life stages over the season, with the simultaneous appearance of juvenile ticks and hatched chicks, but no among-nest spatial structure in tick abundance. Removal sampling significantly reduced tick numbers, but only from the fourth visit onward. Seven bacterial isolates, one parasite species and one viral isolate were detected but no spatial structure in their presence within the colony was found. These results suggest weak isolation among nests and that tick dispersal is likely frequent enough to quickly recolonize locally-emptied patches and disseminate pathogens across the colony. Vector-mediated movements at local scales may therefore play a key role in pathogen emergence and needs to be considered in conjunction with host movements for predicting pathogen circulation and for establishing effective control strategies.

L’hivernage du Cygne de Bewick Cygnus columbianus en Camargue : historique et situation actuelle

Mon, 10 Jan 2022 16:08:33

de Thomas Blanchon, Yves Kayser, Michel Gauthier-Clerc
In Ornithos, 20(5) (2013), 249-254

Il existe trois populations paléarctiques de Cygne de Bewick Cygnus columbianus, définies selon leurs zones d’hivernage. La plus importante est celle de l’Est asiatique, estimée à 92 000 individus, qui se reproduit du delta de la Léna jusqu’à la côte orientale de la Russie et hiverne de l’est de la Chine au Japon et à la Corée du Sud (Wetlands International et al. 2011, Rees & Beekman 2010). La population caspienne/ouest-sibérienne est limitée à quelque 1 000 individus hivernant en mer Caspienne et nichant sur les étendues arctiques de l’ouest sibérien et de la péninsule de Yamal, et peut-être sur celle de Gydan. La population européenne, estimée à 21 500 individus, niche dans la partie européenne de la toundra arctique russe et hiverne en Europe de l’Ouest. Les Cygnes de Bewick hivernant en France appartiennent à cette dernière population .

Recent Circulation of West Nile Virus and Potentially Other Closely Related Flaviviruses in Southern France (2013)

Mon, 26 Oct 2015 10:02:35

de Marion Vittecoq, S. Lecollinet, E. Jourdain, F. Thomas, Thomas Blanchon, Audrey Arnal, S. Lowenski, Michel Gauthier-Clerc
2013

Study of the influenza A virus in wild boars living in a major duck wintering site (2012)

Mon, 26 Oct 2015 10:02:35

de Marion Vittecoq, V. Grandhomme, G. Simon, S. Herve, Thomas Blanchon, F. Renaud, F. Thomas, Michel Gauthier-Clerc, S. Van Der Werf
2012

Mise à jour des connaissances sur l'avifaune de Camargue et des environs (Crau et Alpilles) (2011)

Mon, 26 Oct 2015 10:04:32

de Yves Kayser, Thomas Blanchon, Michel Gauthier-Clerc
2011

Points chauds: La Camargue, delta du Rhône (Bouches-du-Rhône et Gard) (2011)

Mon, 26 Oct 2015 10:04:32

de Yves Kayser, Thomas Blanchon, Michel Gauthier-Clerc
2011

La spatule blanche Platalea leucorodia en Camargue : nidification et hivernage (2010)

Mon, 26 Oct 2015 10:06:42

de Thomas Blanchon, Yves Kayser, Antoine Arnaud, Michel Gauthier-Clerc
2010

Bilan de la fréquentation de la Camargue par la spatule hors reproduction (2010)

Mon, 26 Oct 2015 10:05:25

de Michel Gauthier-Clerc, Thomas Blanchon
2010

Bilan de la reproduction des ibis falcinelles en Camargue (2009)

Mon, 26 Oct 2015 10:05:24

de Michel Gauthier-Clerc, Yves Kayser, Thomas Blanchon
2009

L'ibis falcinelle Plegadis falcinellus nicheur régulier en Camargue (2009)

Mon, 26 Oct 2015 10:04:32

de Yves Kayser, Thomas Blanchon, Michel Gauthier-Clerc
2009