| 1. |
- Le Vaillant, Maryline, et al.
(author)
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Individual parameters shape foraging activity in breeding king penguins
- 2016
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In: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 27:1, s. 352-362
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Journal article (peer-reviewed)abstract
- The variability in individual fitness within a population is likely to be mediated through individual foraging ability and tactics, themselves linked to age-or experience-related processes, but also to differences in individual quality. Not only age, experience, and quality but also sex-related foraging strategies should particularly play an important role in long-lived central-place foragers that have to cope with strong environmental constraints. We monitored the foraging effort (foraging trip durations and number of trips) of 262 known-age micro-tagged king penguins, Aptenodytes patagonicus, at different breeding stages during one of their breeding cycles. We investigated how their age (4-11 years old), sex, past breeding experience (the number of successful breeding attempts), and breeding quality (the expected breeding success, corresponding to the residual of the linear relationship between the age and on the number of past breeding success divided by the number of breeding attempts) affected foraging over a whole breeding season. During the incubation, younger birds (4 years old) undertook longer foraging trips compared with older ones. During the brooding phase and the second period of the creching phase, more experienced birds performed shorter foraging trip than those with a low breeding experience, whereas, during the first period of the creching phase, individuals with better breeding quality performed shorter foraging trips at sea than low breeding quality individuals. Sex-specific foraging patterns were also observed depending on the period of the breeding cycle. Our study shows, for the first time, how foraging effort can be driven by a complex interplay of several individual parameters according to breeding stage and resource availability and abundance.
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| 2. |
- Le Vaillant, Maryline, et al.
(author)
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Telomere length reflects individual quality in free-living adult king penguins
- 2015
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In: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 38:12, s. 2059-2067
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Journal article (peer-reviewed)abstract
- Growing evidence suggests that telomeres, non-coding DNA sequences that shorten with age and stress, are related in an undefined way to individual breeding performances and survival rates in several species. Short telomeres and elevated shortening rates are typically associated with life stress and low health. As such, telomeres could serve as an integrative proxy of individual quality, describing the overall biological state of an individual at a given age. Telomere length could be associated with the decline of an array of physiological traits in age-controlled individuals. Here, we investigated the links between individuals' relative telomere length, breeding performance and various physiological (body condition, natural antibody levels) and life history (age, past breeding success) parameters in a long-lived seabird species, the king penguin Aptenodytes patagonicus. While we observed no link between relative telomere length and age, we found that birds with longer telomeres arrived earlier for breeding at the colony, and had higher breeding performances (i.e. the amount of time adults managed to maintain their chicks alive, and ultimately breeding success) than individuals with shorter telomeres. Further, we observed a positive correlation between telomere length and natural antibody levels. Taken together, our results add to the growing evidence that telomere length is likely to reflect individual quality difference in wild animal.
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| 3. |
- Chambault, Philippine, et al.
(author)
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The Gulf Stream frontal system : A key oceanographic feature in the habitat selection of the leatherback turtle?
- 2017
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In: Deep Sea Research Part I. - : Elsevier BV. - 0967-0637 .- 1879-0119. ; 123, s. 35-47
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Journal article (peer-reviewed)abstract
- Although some associations between the leatherback turtle Dermochelys coriacea and the Gulf Stream current have been previously suggested, no study has to date demonstrated strong affinities between leatherback movements and this particular frontal system using thorough oceanographic data in both the horizontal and vertical dimensions. The importance of the Gulf Stream frontal system in the selection of high residence time (HRT) areas by the North Atlantic leatherback turtle is assessed here for the first time using state-of-the-art ocean reanalysis products. Ten adult females from the Eastern French Guianese rookery were satellite tracked during post-nesting migration to relate (1) their horizontal movements to physical gradients (Sea Surface Temperature (SST), Sea Surface Height (SSH) and filaments) and biological variables (micronekton and chlorophyll a), and (2) their diving behaviour to vertical structures within the water column (mixed layer, thermocline, halocline and nutricline). All the turtles migrated northward towards the Gulf Stream north wall. Although their HRT areas were geographically remote (spread between 80-30 degrees W and 28-45 degrees N), all the turtles targeted similar habitats in terms of physical structures, i.e. strong gradients of SST, SSH and a deep mixed layer. This close association with the Gulf Stream frontal system highlights the first substantial synchronization ever observed in this species, as the HRTs were observed in close match with the autumn phytoplankton bloom. Turtles remained within the enriched mixed layer at depths of 38.5 +/- 7.9 m when diving in HRT areas, likely to have an easier access to their prey and maximize therefore the energy gain. These depths were shallow in comparison to those attained within the thermocline (82.4 +/- 5.6 m) while crossing the nutrient-poor subtropical gyre, probably to reach cooler temperatures and save energy during the transit. In a context of climate change, anticipating the evolution of such frontal structure under the influence of global warming is crucial to ensure the conservation of this vulnerable species.
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| 4. |
- Chambault, Philippine, et al.
(author)
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The influence of oceanographic features on the foraging behavior of the olive ridley sea turtle Lepidochelys olivacea along the Guiana coast
- 2016
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In: Progress in Oceanography. - : Elsevier BV. - 0079-6611 .- 1873-4472. ; 142, s. 58-71
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Research review (peer-reviewed)abstract
- The circulation in the Western Equatorial Atlantic is characterized by a highly dynamic mesoscale activity that shapes the Guiana continental shelf. Olive ridley sea turtles (Lepidochelys olivacea) nesting in French Guiana cross this turbulent environment during their post-nesting migration. We studied how oceanographic and biological conditions drove the foraging behavior of 18 adult females, using satellite telemetry, remote sensing data (sea surface temperature, sea surface height, current velocity and euphotic depth), simulations of micronekton biomass (pelagic organisms) and in situ records (water temperature and salinity). The occurrence of foraging events throughout migration was located using Residence Time analysis, while an innovative proxy of the hunting time within a dive was used to identify and quantify foraging events during dives. Olive ridleys migrated northwestwards using the Guiana current and remained on the continental shelf at the edge of eddies formed by the North Brazil retroflection, an area characterized by low turbulence and high micronekton biomass. They performed mainly pelagic dives, hunting for an average 77% of their time. Hunting time within a dive increased with shallower euphotic depth and with lower water temperatures, and mean hunting depth increased with deeper thermocline. This is the first study to quantify foraging activity within dives in olive ridleys, and reveals the crucial role played by the thermocline on the foraging behavior of this carnivorous species. This study also provides novel and detailed data describing how turtles actively use oceanographic structures during post-nesting migration.
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