Mouvement, Abondance, Distribution


Postdoctorant / Postdoctoral researcherYohan Sassi
Université de Montpellier
CEFE, 3ème étage, bureau 306

I am currently in postdoc (Labex CEMEB grant) using radar data to describe cooperative foraging strategy in griffon vultures and how this strategy is modulated by the food (i.e. carcasses) predictability.

My PhD combined theoretical and applied research questions. For the first I was focusing on the influence of sociality on individual movement decisions and collective foraging strategies of griffon vultures. For the latter, I investigated whether those birds showed avoidance behaviour of wind turbines. To do so I relied on two type of technology: radar and GPS telemetry. PhD supervisors: Olivier Duriez et Yann Tremblay (Marbec).



Address:  CEFE UMR5175 - Campus du CNRS - 1919, route de Mende - 34293 Montpellier 5 - France

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Phone: +33/0 6 59 06 16 59


Postdoc project outline:

Griffon vulture (Gyps fulvus) forages on the carcasses of dead animals, relying on thermal updrafts to travel in search of this food source. In order to exploit these resources, unpredictable in space and time, it has developed specific searching strategies.

To optimize food search, it has been hypothesized that vultures in flight form a large network maintaining sufficient distance to keep conspecifics in sight while searching for carcasses on the ground. Although this hypothesis has been tested by modeling, it has never been demonstrated empirically. During my PhD and now in my postdoc position I am analysing radar data in which we can track a multitude of vultures flying simultaneously within a radius of 6 km around the radar. This will help me to check the century-old hypothesis suggesting a cooperation between griffon vultures when searching carcasses.


Publications (*equal contributions):


- Duriez, O., Camiña-Cardenal, A., Sassi, Y., Blary, C., Chambert, T., Ballester, C., Besnard, A. & Millon, A. (2024). Wind farms and griffon vultures: no evidence for habituation and coexistence, a reply to Farfàn et al. Global Ecology and Conservation, 51, e02921 (

- Sassi, Y., Nouzières, B., Scacco, M., Tremblay, Y., *Duriez, O., & *Robira, B. (2024). The use of social information in vulture flight decisions. Proceedings of the Royal Society B, 291(2018), 20231729. (

- *Duriez, O., *Sassi, Y., Le Gall-Ladevèze, C., Giraud, L., Straughan, R., Dauverné, L., ... & Le Loc’h, G.(2023). Highly pathogenic avian influenza affects vultures’ movements and breeding output. Current Biology, 33(17), 3766-3774 (


In review:

- Sassi, Y., Ziletti, N., *Duriez, O., & *Robira, B., (In review). Unravelling vulture avoidance tactic of wind turbines combining empirical and simulation data. Ornithological Applications (