Interactions Humains Animaux


PhD candidate – Université de Montpellier

Marwan svalbard


I’m a PhD student interested in evolutionary demography and population dynamics of wild populations. I’m currently working on the demography of Svalbard polar bears. I’m relying on 30+ years of data including mark-recapture data, tracking data, and more. I’m mainly using linear models, mark-recapture models and path analysis models in a Bayesian framework to study the determinants of reproductive output, trade-offs between traits, and such.

Sarah Cubaynes (EPHE, CEFE-CNRS), Jon Aars (Norwegian Polar Institute)


Contact information

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Orcid: 0000-0003-1489-9363
GitHub: MarwanNaciri


Project outline

In my first chapter, I investigated the pattern of senescence across several reproductive traits, and in relation to environmental variation in female polar bears. I used generalized linear mixed models in a Bayesian framework to model reproductive output as a function of maternal age, environmental variables, and other relevant variables.

In my second chapter, I’m interested in how offspring survival relates to maternal traits, litter size and cub mass (as well as the interplay between these traits). More specifically, I’m testing hypotheses on how female polar bears optimize their litter size. To do that, I built a model combining path analysis and mark-recapture (PA-MR model), in a Bayesian framework.

In my third chapter, I will use newly available data on denning of female polar bears (assessed with tracking data and geolocation tag data) to (1) feed more data than previously possible to a mark recapture model, (2) estimate denning probability and (3) test several hypotheses on interbirth intervals.

In my final chapter, I will build a population model, using the PA-MR model from chapter 2, the mark-recapture model from chapter 3, and estimates of population size. This will allow to assess the growth rate of the population and the sensitivity of the growth rate to various parameters.


Bio (Background, employment)

  • 2021: Intern – Under the supervision of Sarah Cubaynes. CEFE, Montpellier, France.
    Environmental determinants of litter size and litter production in Svalbard polar bears.
  • 2020: Intern – Under the supervision of Sarah Benhaiem. Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany.
    Patterns and determinants of roadkills in Serengeti Hyenas.
  • 2020: Master’s in biology.
  • 2018: Bachelor’s in biology.


(Co) Supervision of students

  • Ilona Sinn – M2 student: Link between reproductive output and space-use strategy in Svalbard polar bears (co-supervision with Sarah Cubaynes)



  • Naciri, M., J. Aars, M.-A. Blanchet, O. Gimenez, and S. Cubaynes. 2022. Reproductive senescence in polar bears in a variable environment. Frontiers in Ecology and Evolution 10.
  • Naciri, M., A. Planillo, M. Gicquel, M. L. East, H. Hofer, S. Metzger, and S. Benhaiem. 2023. Three decades of wildlife-vehicle collisions in a protected area: Main roads and long-distance commuting trips to migratory prey increase spotted hyena roadkills in the Serengeti. Biological Conservation 279:109950.