|
Jeudi De Grissac S. (2016). Où va la jeunesse ? Mouvements et quête alimentaire des juvéniles de procellariiformes durant leur première année en mer.
|
|
Jouma'a J. (2016). Stratégie d'acquisition des ressources en proies et coût du transport chez l'éléphant de mer austral.
|
|
Le Bras Y. (2017). L'éléphant de mer autral bio-échantillonneur de la distribution des ressources marines.
|
Cornioley Tina, Börger Luca, Ozgul Arpat, Weimerskirch Henri, Gill Jennifer. (2016). Impact of changing wind conditions on foraging and incubation success in male and female wandering albatrosses (Vol. 85).
Abstract: Summary Wind is an important climatic factor for flying animals as by affecting their locomotion, it can deeply impact their life?history characteristics. In the context of globally changing wind patterns, we investigated the mechanisms underlying recently reported increase in body mass of a population of wandering albatrosses (Diomedea exulans) with increasing wind speed over time. We built a foraging model detailing the effects of wind on movement statistics and ultimately on mass gained by the forager and mass lost by the incubating partner. We then simulated the body mass of incubating pairs under varying wind scenarios. We tracked the frequency at which critical mass leading to nest abandonment was reached to assess incubation success. We found that wandering albatrosses behave as time minimizers during incubation as mass gain was independent of any movement statistics but decreased with increasing mass at departure. Individuals forage until their energy requirements, which are determined by their body conditions, are fulfilled. This can come at the cost of their partner's condition as mass loss of the incubating partner depended on trip duration. This behaviour is consistent with strategies of long?lived species which favoured their own survival over their current reproductive attempt. In addition, wind speed increased ground speed which in turn reduced trip duration and males foraged further away than females at high ground speed. Contrasted against an independent data set, the simulation performed satisfactorily for males but less so for females under current wind conditions. The simulation predicted an increase in male body mass growth rate with increasing wind speed, whereas females' rate decreased. This trend may provide an explanation for the observed increase in mass of males but not of females. Conversely, the simulation predicted very few nest abandonments, which is in line with the high breeding success of this species and is contrary to the hypothesis that wind patterns impact incubation success by altering foraging movement.
Keywords: breeding success energy maximizer environmental changes resource acquisition resource allocation time minimizer
Programme: 109
|
|
Fay R. (2017). De l'envol à la première reproduction : aspects écologiques et évolutifs des traits d'histoire de vie de jeunes oiseaux marins longévifs.
|
|
van vliet-Lanoë B., Bergerat F. (coordinators), Geoffroy L., Guillou H., Maury R., Schneider J.-L. (2018). L'Islande au cœur de l'Atlantique Nord : évolutions géodynamique, climatique et environnementale..
|
Fay Rémi, Barbraud Christophe, Delord Karine, Weimerskirch Henri. (2016). Variation in the age of first reproduction: different strategies or individual quality? (Vol. 97).
Abstract: Abstract Although age at first reproduction is a key demographic parameter that is probably under high selective pressure, it is highly variable and the cause of this variability is not well understood. Two non?exclusive hypotheses may explain such variability. It could be the expression of different individual strategies, i.e., different allocation strategies in fitness components, or the consequences of individual difference in intrinsic quality, i.e., some individuals always doing better than others in all fitness components. We tested these hypotheses in the Wandering Albatross investigating relationships between the age at first reproduction and subsequent adult demographic traits. Using finite mixture capture recapture modeling, we demonstrate that the age at first reproduction is negatively related to both reproductive performances and adult survival, suggesting that individual quality was an important factor explaining variation in the age at first reproduction. Our results suggest that age at first breeding is a good predictor of quality in this long?lived seabird species.
Keywords: capture–mark–recapture individual heterogeneity life‐history plasticity reaction norm trade‐off Wandering Albatross
Programme: 109
|
Tiphaine Jeanniard-du-Dot, Andrew W. Trites, John P. Y. Arnould, John R. Speakman, Christophe Guinet. (2016). Flipper strokes can predict energy expenditure and locomotion costs in free-ranging northern and Antarctic fur seals (Vol. 6).
Abstract: Flipper strokes have been proposed as proxies to estimate the energy expended by marine vertebrates while foraging at sea, but this has never been validated on free-ranging otariids (fur seals and sea lions). Our goal was to investigate how well flipper strokes correlate with energy expenditure in 33 foraging northern and Antarctic fur seals equipped with accelerometers, GPS, and time-depth recorders. We concomitantly measured field metabolic rates with the doubly-labelled water method and derived activity-specific energy expenditures using fine-scale time-activity budgets for each seal. Flipper strokes were detected while diving or surface transiting using dynamic acceleration. Despite some inter-species differences in flipper stroke dynamics or frequencies, both species of fur seals spent 3.79 ± 0.39 J/kg per stroke and had a cost of transport of ~1.6–1.9 J/kg/m while diving. Also, flipper stroke counts were good predictors of energy spent while diving (R2 = 0.76) and to a lesser extent while transiting (R2 = 0.63). However, flipper stroke count was a poor predictor overall of total energy spent during a full foraging trip (R2 = 0.50). Amplitude of flipper strokes (i.e., acceleration amplitude × number of strokes) predicted total energy expenditure (R2 = 0.63) better than flipper stroke counts, but was not as accurate as other acceleration-based proxies, i.e. Overall Dynamic Body Acceleration.
Programme: 109
|
Jouma'a Joffrey, Le Bras Yves, Richard Gaëtan, Vacquié‐Garcia Jade, Picard Baptiste, El Ksabi Nory, Guinet Christophe, Costa Daniel. (2016). Adjustment of diving behaviour with prey encounters and body condition in a deep diving predator: the Southern Elephant Seal (Vol. 30).
Abstract: Summary Optimal diving models have been developed to investigate how air?breathing predators should adjust their diving behaviour to optimize their foraging efficiency. Using time?depth recorders and 3D accelerometers, we addressed this question on six free?ranging Southern Elephant Seal (SES) females equipped on Kerguelen Island. We hypothesize that seals would initially increase their foraging time with distance to the foraging patches before reducing it for physiological reasons, regardless of the prey encountered. We expect that SES spends more time at depths where more Prey Catch Attempts (PCA) occur, that is at the bottom. We also hypothesize that bottom time should be related to both the seal body density and the swimming effort dedicated to catching prey, as we expect seals to be more active when catching prey. Finally, because oxygen is acquired at the surface only, we expect that recovery times increase with the duration of the previous dives. A total of 72·6% of PCA detected by accelerometer occurred at the bottom of the dive. At shallow depths (<300 m), seals spent more time at the bottom in dives where PCA occurred compared to non?PCA dives. At deeper depths, SES had shorter bottom times in PCA dives due to higher swimming effort. When only dives associated with PCA were considered, the time spent at the bottom increased with the number of PCA. In addition, the closer the seal was to neutral buoyancy, the longer was the bottom duration. Body density, that is buoyancy, was found to be a critical factor in controlling variations in the dive duration through the swimming effort to access the prey at the bottom of the dive. Finally, post?dive surface intervals were related to the duration and swimming effort of the previous dive. This study reveals how a marine top predator adjusts the time spent at the bottom depending on its body density, prey encounter rate and prey accessibility. It also highlights that using the duration of the foraging phase as a proxy of foraging success can be seriously misleading in SES. Finally, the need to use an energetic approach with bio?logging technology to study behavioural ecology is emphasized.
Keywords: bio‐logging buoyancy foraging behaviour marine mammal optimal diving theory
Programme: 109
|
L. Kernaléguen, J. P. Y. Arnould, C. Guinet, B. Cazelles, P. Richard, Y. Cherel. (2016). Early-life sexual segregation: ontogeny of isotopic niche differentiation in the Antarctic fur seal (Vol. 6).
Abstract: Investigating the ontogeny of niche differentiation enables to determine at which life-stages sexual segregation arises, providing insights into the main factors driving resource partitioning. We investigated the ontogeny of foraging ecology in Antarctic fur seals (Arctocephalus gazella), a highly dimorphic species with contrasting breeding strategies between sexes. Sequential δ13C and δ15N values of whiskers provided a longitudinal proxy of the foraging niche throughout the whole life of seals, from weaning, when size dimorphism is minimal to the age of 5. Females exhibited an early-life ontogenetic shift, from a total segregation during their first year at-sea, to a similar isotopic niche as breeding females as early as age 2. In contrast, males showed a progressive change in isotopic niche throughout their development such that 5-year-old males did not share the same niche as territorial bulls. Interestingly, males and females segregated straight after weaning with males appearing to feed in more southerly habitats than females. This spatial segregation was of similar amplitude as observed in breeding adults and was maintained throughout development. Such early-life niche differentiation is an unusual pattern and indicates size dimorphism and breeding constraints do not directly drive sexual segregation contrary to what has been assumed in otariid seals.
Programme: 109
|
