Selection of habitats by two closely-related shorebird species wintering on the French Atlantic coast : Study of the bar-tailed and black-tailed godwits

• Main Author: Jourdan, Clément
• Other Authors: LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Université de La Rochelle, Pierrick Bocher, Jérôme Fort
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2021
• Subjects: Shorebirds; Intertidal mudflats; Wintering strategy; Habitat selection; GPS tracking; Oiseaux limicoles; Vasière intertidales; Stratégie hivernale; Sélection d’habitats; Télémétrie GPS; [SDV.BA]Life Sciences [q-bio]/Animal biology; Noire; Iceland; Alaska; barge à queue noire; black-tailed godwit; Limosa limosa; Siberia
• Online Access: https://theses.hal.science/tel-03606976; https://theses.hal.science/tel-03606976/document; https://theses.hal.science/tel-03606976/file/2021JOURDAN171837.pdf

The bar-tailed godwit (Limosa lapponica) and the black-tailed godwit (Limosa limosa) are two migratory shorebird species that spend the winter on the French Atlantic coast, before to reach regions further north for breeding. These two species share great phylogenetic proximity, and great morphological similarities inherited from a common ancestor from which they recently diverged. In such “closely-related” species, although identical responses are generally observed facing the same environmental conditions, the existence of unique niche properties and specific ecological needs have already been described. It is the case in bar-tailed and black-tailed godwits, which share the same wintering areas, but have a distinct reproduction distribution, breeding respectively in northern Eurasia and Alaska, and from Iceland to eastern Siberia. In France, we mainly observe the subspecies L. lapponica lapponica for bar-tailed godwit, and the subspecies L. limosa islandica for black-tailed godwit, which are present throughout the wintering period (August-April). The subspecies L. lapponica taymyrensis and L. limosa limosa are only present during the migration periods (February-March and August-October). In winter, L. l. lapponica and L. l. islandica mainly use mudflat ecosystems, on which they depend for feeding, as well as marine and coastal marshes, for roosting. Thus, in the Pertuis Charentais (France), they use the same wintering sites and the same functional areas, but exhibit distinct food preferences with a diet dominated by polychaetes worms for the bar-tailed godwit, and bivalves (eg Macoma balthica) and seagrass rhizomes (Zostera noltei) for the black-tailed godwit. Beyond this knowledge, this thesis aims to describe and compare the winter survival strategies of these two species, and especially their spatio-temporal use of habitats. The recent miniaturization of GPS tracking loggers has enabled us to equip individuals of both species to access to their daily and seasonal movements. Such an approach can significantly ...