Movements and foraging strategies of juveniles procellariiformes during their first months of independence

• Main Author: Jeudi de Grissac, Sophie
• 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, Henri Weimerskirch
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2016
• Subjects: Seabirds; Albatros; Petrels; Ecology; Strategy; Behaviour; Southern Ocean; Early life; Oiseaux marins; Pétrels; Écologie; Stratégie; Comportement; Océan Austral; Début de vie; [SDV.SA]Life Sciences [q-bio]/Agricultural sciences; Austral; Kerguelen
• Online Access: https://theses.hal.science/tel-01661452; https://theses.hal.science/tel-01661452/document; https://theses.hal.science/tel-01661452/file/2016JeudideGrissac94275B.pdf

The juvenile stage of animals is often much of a mystery to scientists. Moreover, juvenile survival is known to be a strong determinant for the future of a population. Indeed, juvenile animals are known to face high mortality during the first months after independence, with survival rates improving with age. One ultimate hypothesis implies that juveniles have a lower survival rate than adults because of their lack of experience. Thus they are initially poor foragers and require a learning period (immaturity) to improve their efficiency before being able to bear breeding and its associated energetic costs. Proximal factors also influence juvenile survival, such as environmental fluctuations and competition. Studies on terrestrial animals have provided useful information thanks to the possibility of direct observation and, recently, bio-logging technologies. However, collecting data in the marine environment is more difficult, particularly when juveniles are concerned. Long-lived marine species such as seabirds have an extensive immature period extending from a few years up to more than ten years. The offspring of these species will usually leave their natal site and disperse at sea for several years before returning to breed on land, most of the time at their place of birth. This makes it difficult to obtain direct observations, and so documenting their first journey at sea to learn more about their behavioural and foraging ecology is a challenge. In this context, this PhD aims to unravel at least part of the mystery of juvenile seabirds’ early life by investigating the first months at sea of newly fledged individuals from several long-lived species of procellariiformes. Using state of the art advancements in biotelemetry, I was able to follow, at sea, by satellite a large set of juveniles from nine closely related species of albatross and petrel breeding in the French Southern Territories of the Southern Ocean : Crozet, Kerguelen and Amsterdam Islands. Some of these species had never been tracked before. ...