On the 22th September 2014, 3 members of the EarlyLife program went to the BL5 Symposium in order to present the first results on theirs juvenile’s seabird studies.
Sophie de Grissac (Phd Student) has shown in a comparative study the different foraging strategy of nine species of juvenile albatrosses and petrels.
The early life at sea of juvenile albatrosses and petrels
Sophie de Grissac, Henri Weimerskirch, Lucas Börger, Audrey Guitteaud
In long-lived species, juveniles and immatures, represent up to 50% of the total population. Therefore, in order to understand the dynamics of those populations, it is essential to better understand their foraging ecology that remains, until recently, poorly known. We tracked the juveniles of ten species of Procellariiformes in the Southern Ocean during their first month at sea in order to examine how their foraging strategy differ from that of adults, and how they differ between species whose adults show contrasted foraging habits. (1) We use multifactorial analyses of trajectory parameters in order to characterize and compare the different foraging strategies. Within species,birth colony and sex can affect individual strategy and foraging zones. (2) We find that species differ extensively from dispersive to true migratory behavior. Most juveniles of each species follow,the migration or dispersion patterns of non-breeding adults, showing an innate ability for navigation toward preferred foraging places. However, for two species we observe a clear contrast between foraging strategies of adult and juveniles. Important sex specific differences also occur for some species. We discuss the implication of these results in terms of the evolution of the foraging behavior of naïve individuals.
PDF presentation : The early life at sea of juvenile albatross and petrel
Aurélien Prudor has meanwhile presented the Impact of extreme climatic events on the foraging behavior of juveniles tropical seabirds on Europa Island.
Impact of environmental variability and extreme events on foraging of tropical seabirds
In addition to an increase in temperatures, decrease in productivity, and change in wind regimes, future climate changes are expected to be associated to an increase in extreme climatic events. How will climate change and extreme climatic events such as storms affect the foraging abilities of marine vertebrates is still poorly known. During a long-term study on the effects of climate variability on foraging abilities of tropical seabirds, several cyclones have affected the foraging zones of red-footed boobies and great frigatebirds. We show that the two species were affected extensively in their foraging abilities by annual variation in the average environmental conditions. When cyclones affect the breeding grounds, on the colony juveniles and adult birds reacted differently in their foraging decisions in relation to the potential specific fitness consequences. When encountering storms at sea adult birds try to avoid the center of low-pressure systems, and can be transported far from colonies. We discuss potential consequences of climate change and of increase in stormy conditions on seabird populations.
PDF presentation : Impact of extreme climatic events on foraging of tropical seabirds
Mathieu Gesta, student in Master 2 BBEM, illustred the results of diving behavior of juveniles elpehant seals during a poster session.
Ontogenic changes in the foraging behaviour of naive southern elephant seal pups using a new generation of onboard data processing and satellite data relayed tag
Gesta Mathieu1, Picard Baptiste1, Joumaa Joffre1y, Vacquié Garcia Jade1, Lindstrom Todd2, Rutishauser Matthew 2 Weimerskirch Henri 1, Guinet Christophe 1
1: Centre d’Études Biologiques de Chizé, CNRS UMR7372, Université de La Rochelle, France
Large datasets are collected at high frequency by multi-sensors loggers to investigate the foraging ecology of marine predators. However they need to be recovered to process the data too voluminous to be successfully transmitted. Therefore our understanding of the foraging behaviour is strongly biased toward land based species, breeding individuals and those surviving. As part of the Early Life program, the ontogeny of the foraging behaviour of 4 naïve southern elephant seal pups was investigated using new logging and onboard data processing tags DSA (dive segment analysis) measuring pressure, light, temperature and 3D acceleration. Dives were split in five time/depth segments using a broken stick algorithm. Swimming effort, number of prey catch attempts (PCA), the descent and ascent angles were calculated from accelerometry data and a summary transmitted through Argos. From 1 to 8 weeks, dive depth and duration increased from 71±24m to 165±39m, and 372±74s to 464±82s respectively (30% of adult female performances on week8). Pups performed 3.2±1.4 PCA/min, with PCA varying mainly with foraging locations. Pups exhibited a nycthemeral foraging pattern, diving deeper and being least successful during the day. These tags open a new way to investigate the ecology of poorly known and accessible marine species.