Séminaire : Intraspecific variation in environmental and geographic space use: insights from individual movement data

Séminaire CEFE
Vendredi 27 avril 2018 –  15:00
Grande salle de réunion du CEFE | 1e étage, aile C

Suivi d’un pot de thèse dans la Rotonde du CEFE


anne sophie

Anne-Sophie Bonnet-Lebrun
Presentation of the results of a joint PhD thesis at the University of Cambridge + CEFE

Thesis summary: Species’ ranges arise from the interplay between environmental preferences, biotic and abi-otic environmental conditions, and accessibility. Understanding of – and predictive models on – species distri-butions often build from the assumption that these factors apply homogenously within each species, but there is growing evidence for individual variation. Here, I use movement data to investigate individual-level decisions and compromises regarding the different costs and benefits influencing individuals’ geographic locations, and the species-level spatial patterns that emerge from these. I first developed a new method that uses tracking data to quantify individual specialisation in geographic space (site fidelity) or in environmental space (environ-mental specialization). Applying it to two species of albatrosses, I found evidence of site fidelity but weak envi-ronmental specialisation. My results have implications for how limited research efforts are best-targeted: if an-imals are generalists, effort are best spent by understanding in depth individual patterns, i.e., better to track fewer individuals for long periods of time; whereas if animals tend to be specialists, efforts should be dedicated to tracking as many individuals as possible, even if for shorter periods. I then investigated individual migratory strategies and their drivers in nine North American bird species, using ringing/recovery data. I found latitudinal redistribution of individuals within the breeding and non-breeding ranges that generally did not follow text-book patterns (‘chain migration’ or ‘leapfrog migration’). Migratory individuals tend to trade off the benefits of migration (better tracking of climatic niche; better access to resources) and its costs (increasing with migratory distance). I found that birds are more likely to remain as residents in areas with warmer winter temperatures, higher summer resource surpluses and higher human population densities (presumably because of a buffering effect of urban areas). Overall, my results highlight the importance of considering individual variation to under-standing the ecological processes underpinning species’ spatial patterns.

Thesis supervisors: Andrea Manica (Dep. of Zoology, University of Cambridge) and Ana Rodrigues (équipe DPB, CEFE)

(Seminar in English, with Questions & Answers in English + French)