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LPO
Brest, France

This topic was studied in winter on the intertldal mudflats of the Bay of Marennes-Oleron (Western France). Main differences between sexes appeared in diet with males preying more on shore crabs and females preying more on bivalves. Males spent more time in prey handling and cleaning activities. Females spent more time in vigilance behaviour. Handling time was significantly different between sexes according to type and depth of prey. Sexual size dimorphism in bill length and prey availability were thought to explain most of the observed differences in feeding behaviour and diet in this species.


Duriez O.,CNRS Science Conservation Center | Duriez O.,CNRS Center of Evolutionary and Functional Ecology | Eliotout B.,LPO | Sarrazin F.,CNRS Science Conservation Center
Ringing and Migration | Year: 2011

Griffon Vultures Gyps fulvus are notoriously difficult to age precisely, given their delayed maturity and large inter-individual variation. However assessing the age of young individuals can be important for studies dealing with behaviour, population dynamics and conservation. Using a large sample of individually marked Griffon Vultures of known age in southern France, we studied changes with age of morphological parameters observable at distance on the ground. Combining features of bill colour, eye colour, shape and colour of neck ruff feathers and shape of upperwing greater coverts, it was possible to attribute age classes with a precision of c 2 years. The first characteristics to change were the colour of the bill, with the front of the bill getting clear before the sides of the bill, and the shape of the greater coverts, where pointed juvenile feathers were replaced by paler and more rounded feathers. In the second year, the ruff turned progressively paler and shorter to become adult-like in the seventh year for most individuals. The eye turned lighter only in the fifth year. Males tended to acquire adult plumages more rapidly than females. © 2011 British Trust for Ornithology.


Carton X.,LPO
IUTAM Bookseries | Year: 2010

The interaction of two identical vortices at different depths is studied in a two-layer quasi-geostrophic flow with external shear or strain. The equilibria and stability of point vortices are computed, as well as their possible resonance with the forcing. The various evolutions of finite-area vortices (alignment, co-rotation, equilibria, oscillations) are presented and compared with point-vortex dynamics. © 2010 Springer Science+Business Media B.V.


Roehrig R.,CNRM GAME | Bouniol D.,CNRM GAME | Guichard F.,CNRM GAME | Hourdin F.,LMD | Redelsperger J.C.,LPO
Journal of Climate | Year: 2013

The present assessment of the West African monsoon in the models of the Coupled Model Intercomparison Project (CMIP) phase 5 (CMIP5) indicates little evolution since the third phase of CMIP (CMIP3) in terms of both biases in present-day climate and climate projections. The outlook for precipitation in twenty-first-century coupled simulations exhibits opposite responses between the westernmost and eastern Sahel. The spread in the trend amplitude, however, remains large in both regions. Besides, although all models predict a spring and summer warming of the Sahel that is 10%-50% larger than the global warming, their temperature response ranges from 0 to 7 K. CMIP5 coupled models underestimate the monsoon decadal variability, but SST-imposed simulations succeed in capturing the recent partial recovery of monsoon rainfall. Coupled models still display major SST biases in the equatorial Atlantic, inducing a systematic southward shift of the monsoon. Because of these strong biases, the monsoon is further evaluated in SST-imposed simulations along the 108W-108E African Monsoon Multidisciplinary Analysis(AMMA)transect, across a range of time scales ranging from seasonal to intraseasonal and diurnal fluctuations. The comprehensive set of observational data now available allows an in-depth evaluation of the monsoon across those scales, especially through the use of high-frequency outputs provided by some CMIP5models at selected sites along the AMMA transect. Most models capture many features of the African monsoon with varying degrees of accuracy. In particular, the simulation of the top-of-atmosphere and surface energy balances, in relation with the cloud cover, and the intermittence and diurnal cycle of precipitation demand further work to achieve a reasonable realism. © 2013 American Meteorological Society.


Carton X.,LPO | L'Hegaret P.,LPO | Baraille R.,Meteo - France
Ocean Science | Year: 2012

By analysing ARGO float data over the last four years, a few aspects of the mesoscale variability of water masses in the Arabian Sea are described. The Red Sea Outflow Water (RSOW) is concentrated in the Southwestern Gulf of Aden, in particular when a cyclonic gyre predominates in this region. Salinities of 36.5 and temperatures of 16°C are found in this area at depths between 600 and 1000 m. RSOW is more dilute in the eastern part of the Gulf, where intense and relatively barotropic gyres mix it with Indian ocean Central Water. RSOW is also detected along the northeastern coast of Socotra, and fragments of RSOW are found between one and three degrees of latitude north of this island. In the whole Gulf of Aden, the correlation between the deep motions of the floats and the sea-level anomaly measured by altimetry is strong, at regional scale. The finer scale details of the float trajectories are not sampled by altimetry and are often related to the anomalous water masses that the floats encounter. The Persian Gulf Water (PGW) is found in the float profiles near Ras ash Sharbatat (near 57° E, 18° N), again with 36.5 in salinity and about 18-19 °C in temperature. These observations were achieved in winter when the southwestward monsoon currents can advect PGW along the South Arabian coast. Fragments of PGW were also observed in the Arabian Sea between 18 and 20° N and 63 and 65° E in summer, showing that this water mass can escape the Gulf of Oman southeastward, during that season. Kinetic energy distributions of floats with respect to distance or angle share common features between the two regions (Gulf of Aden and Arabian Sea), in particular peaks at 30, 50 and 150 km scales and along the axis of monsoon currents. Hydrological measurements by floats are also influenced by the seasonal variations of PGW and RSOW in these regions. © 2012 Author(s).

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