Foraging strategies and prey distribution : the example of air-breathing predators foraging in the pelagic environment

• Main Author: Tessier, Eugénie
• Other Authors: Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), Institut National de la Recherche Agronomique (INRA)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Université de La Rochelle, Charles-André Bost, Yves Cherel
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2019
• Subjects: Behaviour ecology; Foraging; Prey distribution; Active acoustic; Penguins; Southern Ocean; Écologie comportementale; Recherche alimentaire; Distribution des proies; Acoustique active; Manchots; Océan austral; [SDV.AEN]Life Sciences [q-bio]/Food and Nutrition; Austral; Kerguelen; Kerguelen Island; Antarc*; Antarctique*; Eudyptes chrysolophus; King Penguins
• Online Access: https://theses.hal.science/tel-03193929; https://theses.hal.science/tel-03193929/document; https://theses.hal.science/tel-03193929/file/2019Tessier150007.pdf

In the pelagic environment, the resource is heterogeneously distributed. Therefore, prey are aggregated in patch. In 2014, the program MyctO-3D-Map collected information on both prey distribution and foraging behaviour of diving predators (penguins). The aim of this thesis was to evaluate the foraging strategies of diving predators breeding at Kerguelen Island according to prey distribution. At the dive scale, king penguins (Aptenodytes patagonicus) and macaroni penguins (Eudyptes chrysolophus) adjusted their foraging behaviour depending on the foraging behaviour of the preceding dive. Our results suggested that when penguins encountered a favourable area, they decreased surface time and dived to the same depth as the previous dive. Penguins performed dives in discrete series called bouts, similarly to several other diving predators. In prey capture attempt bouts (PCA bouts), king and macaroni penguins modified their diving behaviour with the length of PCA bouts: longer PCA bouts were associated with higher foraging activity and shorter transit phases. Moreover, the density of PCA bouts was similarly to the density of fish patches. These results suggested that the functional foraging unit for king penguins was the PCA bout. At the scale of the entire prospected area, king penguins moved towards area less rich in biomass, but where prey patches are more accessible. This survey is one of the few that compares simultaneously acoustic data and foraging behaviour of penguins. The distribution of fish patch and their accessibility is one of the most important parameter influencing the foraging behaviour of diving predators. En milieu océanique, la ressource est distribuée de façon hétérogène. De ce fait, les proies sont souvent regroupées en bancs (« patchs »). En 2014, le projet MyctO-3D-Map a permis de récolter au large de Kerguelen (Terres Australes et Antarctiques Françaises) des données simultanément sur la distribution des proies en milieu pélagique et sur le comportement de plongée de prédateurs marins. ...