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PhD title

Impact of climatic variability, density-dependence and individual heterogeneity on predator prey system


Research period




Christophe BARBRAUD


Registration University

University of La Rochelle / École doctorale Gay Lussac



Skua, Top predator, Population dynamic, Population ecology, Mark-recapture, State-space model, Bayesian


Research project

Background: A key challenge in ecology is to anticipate the impact of climate change on community and ecosystems. Several studies showed climate change impacts on animal populations, but most of retrospective or prospective studies ignore species interactions, particularly the way in which climatic variability, density-dependence and predation interact to regulate predator-prey system dynamic. Consequently, the combined effect of all these variables on biodemographic components (survival, fecundity, first breeding age…) is not well documented. This stage is however essential in predictive modelling construction. Moreover, it has recently been shown that climatic variability and density-dependence could interact with interindividual heterogeneity (age, sex…) and impact in several distinctive ways biodemographic components. Finally, in predator, this interindividual heterogeneity determines individual foraging strategies, individual efficiency to acquire their prey, and thus their phenotypic value. A major issue is to estimate interaction effects between climatic variability, density-dependence, predation and individual heterogeneity on demographic components and population dynamics.


Goals: My PhD central objective is to determine what are the demographic responses of two phylogenetically closely related predator species are to prey abundance fluctuation, in two contrasted biomes. First, the effect of prey abundance, but also of climate, density-dependence and individual heterogeneity (age, sex, experience…) on several demographic parameters of predators will be quantified. This will allow the modeling of predator population dynamic and the determination of population growth rate sensibility to prey abundance fluctuations (as well as sensibility to climatic factors and population density). Second, climate and population density effects on demographic parameters of prey will be examined in order to determine prey population growth rate sensibility. From a practical point of view, this will be the determination of functional responses of predator demographic rates to prey abundance variation, and to integrate these functional responses in predator-prey population dynamic models (e.g. generalized Lotka–Volterra or other).


Source of data and analytical methods: The data comes from individual monitoring by mark-recapture and from long-term population monitoring (50 years of monitoring). Monitoring species are two top predators:  Brown skua Stercorarius antarcticus in the Kerguelen Islands and South Polar Skua Stercorarius maccormicki in Terre Adélie, Antarctica, and prey species: Blue petrel Halobaena caerulea and Slender-billed prion Pachyptila beicheri in the Kerguelen Islands and Adélie penguin Pygoscelis adeliae and Emperor penguin Aptenodytes forsteri in Antarctica. These species are also monitored and their behavior and spatio-temporal distribution are now well known. This would facilitate the better understanding of ecological mechanisms causing the demographic variation measured. These species are studied in the French Southern and Antarctic Territories (TAAF) with the support of the Paul-Emile Victor French Polar Institute (IPEV) and Subantarctic and Arctic Workshop Area (ZATA). Analytical tools used are multi-states and multi-events mark-recapture models, matrix population models, and also analysis tools of time series (Bayesian state-space model, GLM, GAM…).


Internship report 

PACOUREAU Nathan. 2015. Effet de la densité-dépendance sur la croissance et la survie pré-sevrage d’otaries à fourrure subantarctique (Arctocephalus tropicalis) de l’île d’Amsterdam. Master 2, Patrimoine Naturel et Biodiversité, Université de Rennes 1 (PDF)





Centre d'Etudes Biologiques de Chizé


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