|Les articles de Samuel Hilaire||https://tourduvalat.centredoc.fr/rss.php?id=49|
Les articles de Samuel Hilaire
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.
de Clelia Sirami, Nicolas Gross, Aliette Bosem Baillod, Colette Bertrand, Romain Carrié, Annika Hass, Laura Henckel, Paul Miguet, Carole Vuillot, Audrey Alignier, et al.
In Proceedings of the National Academy of Sciences, 116(33) (2019-08-13), 16442-16447
En ligne : www.pnas.org[...]
Agricultural landscape homogenization has detrimental effects on biodiversity and key ecosystem services. Increasing agricultural landscape heterogeneity by increasing seminatural cover can help to mitigate biodiversity loss. However, the amount of seminatural cover is generally low and difficult to increase in many intensively managed agricultural landscapes. We hypothesized that increasing the heterogeneity of the crop mosaic itself (hereafter “crop heterogeneity”) can also have positive effects on biodiversity. In 8 contrasting regions of Europe and North America, we selected 435 landscapes along independent gradients of crop diversity and mean field size. Within each landscape, we selected 3 sampling sites in 1, 2, or 3 crop types. We sampled 7 taxa (plants, bees, butterflies, hoverflies, carabids, spiders, and birds) and calculated a synthetic index of multitrophic diversity at the landscape level. Increasing crop heterogeneity was more beneficial for multitrophic diversity than increasing seminatural cover. For instance, the effect of decreasing mean field size from 5 to 2.8 ha was as strong as the effect of increasing seminatural cover from 0.5 to 11%. Decreasing mean field size benefited multitrophic diversity even in the absence of seminatural vegetation between fields. Increasing the number of crop types sampled had a positive effect on landscape-level multitrophic diversity. However, the effect of increasing crop diversity in the landscape surrounding fields sampled depended on the amount of seminatural cover. Our study provides large-scale, multitrophic, cross-regional evidence that increasing crop heterogeneity can be an effective way to increase biodiversity in agricultural landscapes without taking land out of agricultural production. / Cet article est issu du projet Farmland (2011-2015) financé par Biodiversa et réalisé sur 7 sites Européens dont la Camargue. Cette étude s’appuie sur deux saisons intensives de terrain pour échantillonner les plantes, insectes et oiseaux sur les parcelles agricoles. Ces données, combinées à une numérisation précise du paysage sur SIG, ont permis de démontrer qu’il était possible d’augmenter la biodiversité et les services qu’elle rend aux agriculteurs (pollinisation, contrôle des ravageurs) en diversifiant le nombre de cultures et en réduisant la taille des parcelles, sans nécessairement diminuer la surface agricole utile.
de Brigitte Poulin, Gaëtan Lefebvre, Camille Muranyi-Kovacs, Samuel Hilaire
In International Journal of Environmental Research and Public Health, 14(3) (2017-03-18), 313
En ligne : www.mdpi.com[...]
We tested the use of mosquito traps as an alternative to spraying insecticide in Camargue (France) following the significant impacts observed on the non-target fauna through Bti persistence and trophic perturbations. In a village of 600 inhabitants, 16 Techno Bam traps emitting CO2 and using octenol lures were set from April to November 2016. Trap performance was estimated at 70% overall based on mosquitoes landing on human bait in areas with and without traps. The reduction of Ochlerotatus caspius and Oc. detritus, the two species targeted by Bti spraying, was, respectively, 74% and 98%. Traps were less efficient against Anopheles hyrcanus (46%), which was more attracted by lactic acid than octenol lures based on previous tests. Nearly 300,000 mosquitoes from nine species were captured, with large variations among traps, emphasizing that trap performance is also influenced by surrounding factors. Environmental impact, based on the proportion of non-target insects captured, was mostly limited to small chironomids attracted by street lights. The breeding success of a house martin colony was not significantly affected by trap use, in contrast to Bti spraying. Our experiment confirms that the deployment of mosquito traps can offer a cost-effective alternative to Bti spraying for protecting local populations from mosquito nuisance in sensitive natural areas.
de Philippe Lambret, Samuel Hilaire, Robby Stoks
In International Journal of Odonatology (2017), 1–12
En ligne : www.tandfonline.com[...]
Although a full life cycle approach is optimally needed to make conservation decisions, the egg stage is often neglected for insect species of special conservation interest. Water management and related abiotic
factors are relevant factors to consider in aquatic species. Lestes macrostigma is a threatened damselfly restricted to temporary brackish waters. Here we provide detailed information on its hatching success and
phenology in two natural field populations. Shoots containing fresh egg clutches of L. macrostigma were sampled in late June, just after the oviposition period. In the fall, shoots were separately placed in plastic
boxes in two ponds in southern France. Examination of eggs indicated L. macrostigma overwinters at an early embryonic stage. The following spring we monitored hatching in detail. Hatching began on 15 March in both ponds and ended on 27 April. Hatching was synchronized, with half of the eggs hatching within five days in the first pond and 14 days in the second pond. Lower water temperatures decreased hatching success and likely also delayed hatching. Embedment of shoots in ice increased egg mortality.
Based on our data, wildlife managers are encouraged to maintain water levels high during winter to reduce the risk of freezing of L. macrostigma eggs.
de Héctor Rodríguez-pérez, Samuel Hilaire, François Mesléard
In Hydrobiologia, 767(1) (March 2016), 333-345
En ligne : link.springer.com[...]
Temporary ponds, acknowledged for their conservation value, are colonized by the invasive crayfish Procambarus clarkii. We have tested the consequences of this colonization for the ecosystem under two contrasted scenarios: one single individual arrival or three individuals arrival. We recreated the temporary pond ecosystem in 1 m2 tanks to investigate the impact of the two crayfish densities. We studied the macrophyte community composition and abundance, chlorophyll a and total suspended solids concentrations, and the diversity and functional composition of micro-crustacean and macro-invertebrate communities. We observed a reduction of macrophyte biomass in experimental crayfish mesocosms in comparison with control tanks, nearly 80 and 40% less in 3 and 1 crayfish/m2 tanks, respectively. The macrophyte community shifted, followed by a filamentous algae development, an increase of bare sediment and turbidity in crayfish tanks. The macro-invertebrate community suffered a richness loss of 28 and 22%, in 3 and 1 crayfish/m2 tanks, respectively. Functionally, macro-invertebrate diversity reduction most strongly affected the grazer, detritivore and predator trophic groups. Microcrustaceans seemed not to be affected by the introduction of the crayfish. The introduction of the crayfish greatly altered the ecosystem structure and subsequently the ecosystem functioning.
de E. Meineri, H. Rodriguez-perez, Samuel Hilaire, François Mesléard
de H. Rodriguez-perez, H. Cayuela, Samuel Hilaire, Anthony Olivier, François Mesléard
de N. Vincent-martin, Antoine Arnaud, Samuel Hilaire