Relationship between freshwater invertebrates and Northern shoveler Spatula clypeata in prenuptial stopover in two wetlands of Vendée (France)

• Main Author: Moreau, Axelle
• Other Authors: LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Université de La Rochelle, Pierrick Bocher, Christine Dupuy, Sébastien Farau
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2023
• Subjects: Wetlands; Northern shoveler; Freshwater invertebrates; Habitat; Prenuptial stopover; Isotopic niche; Zones humides; Canard souchet; Invertébrés d'eau douce; Halte prénuptiale; Niche isotopique; [SDV.BA]Life Sciences [q-bio]/Animal biology; [SDV.SA]Life Sciences [q-bio]/Agricultural sciences; Northern Shoveler; Shoveler
• Online Access: https://theses.hal.science/tel-04256010; https://theses.hal.science/tel-04256010/document; https://theses.hal.science/tel-04256010/file/2023Moreau205883.pdf

"Income breeder", the Northern shoveler Spatula clypeata makes several stopovers between its wintering and breeding site in order to replenish its reserves and complete its pre-breeding migration. Freshwater invertebrates are the main prey of the Northern shoveler and are captured mainly by filtration. This research project had three main objectives: (1) to understand the abundance, diversity, and habitat of freshwater invertebrates in two wetlands known for their high abundance of Northern shoveler, the Marais breton, and the Marais poitevin; (2) to study the environmental and nutrient characteristics of the habitats used by the Northern shoveler during its prenuptial stopover; (3) to define habitat management measures in favour of all of the species groups studied. This study showed that the ponds studied were abundant in freshwater invertebrates. The study defined four habitat typologies based on environmental variables and the presence of some key invertebrate taxa. During migratory stopover, the Northern shoveler used different habitats with a nychthemeral rhythm. Daytime sites were deep and sparsely vegetated habitats dominated by microcrustaceans, while nighttime sites were shallow and vegetated habitats with high invertebrate taxonomic diversity. Home range sizes did not differ between the two wetlands, between sexes or between age classes (juveniles and adults). Finally, this study revealed that during the prenuptial stopover, the Northern shoveler fed mainly on Cladocera, Copepoda, Chironomidae larvae, Pleidae and Particulate Organic Matter. The results of this work could help to define management and habitat conservation measures for all the species studied. « Reproducteur sur revenu », le Canard souchet Spatula clypeata réalise plusieurs haltes migratoires entre son site d’hivernage et de reproduction afin de reconstituer ses réserves et d’achever sa migration prénuptiale. Les invertébrés d’eau douce constituent les principales proies du Canard souchet et sont capturés principalement par ...