Research

My research lies at the interface of biology, statistical physics and applied mathematics. I use a collection of empirical, statistical and modelling methods to investigate, from experiments, the mechanisms responsible for the collective behaviours of animals, including insect societies or fish shoals. In particular, I have strong interests in use of space and movements, i.e. how social groups move together through space in a synchronised and coordinated manner.

The patterns generated by collective motion in fish schools and bird flocks have fascinated humans for centuries, but only in recent decades have advances in modelling and data acquisition allowed collective motion to be investigated with scientific rigour. To research these complex systems is challenging for several reasons, the main one being that different individual rules can lead to the same collective behaviours. It is therefore difficult to infer and disentangle the individual rules from the collective behaviours themselves. The study of these systems with an integrative perspective requires a specific and interdisciplinary framework, especially combining modelling and empirical work at different scales.

Current and past positions

• Sept 2023 - Now Postdoctoral Research Fellow in Pawel Romanczuk's group at Humboldt University, Berlin, Germany.
  
  
• Jun 2021 - Aug 2023 Postdoctoral Research Fellow in Richard Mann's group at the University of Leeds, UK.
  
  
• Oct 2018 - Jan 2021 Postdoctoral Research Associate in Elva Robinson's group at the University of York, UK. I model the networks of trails in polydomous ants, in collaboration with Matina Donaldson-Matasci (Harvey Mudd College, USA) and Scott Powell (George Washington University, USA).
  
  
• Jul - Oct 2018 Research assistant in Christos Ioannou's group at the University of Bristol, UK. I develop a pilot method encompassing a tracking process derived from optic flow techniques and a machine learning analysis in order to predict traits of large groups of fish as measured on video footage.

Publications

• Jan 2026 Lecheval V & Romanczuk P. Future practices of interdisciplinary research in collective animal behaviour. Journal of the Royal Society Interface (Open Access).
• Apr 2025 Piross I, Lecheval V et al. Strong and weak environmental perturbations cause contrasting restructure of ant transportation networks. Proceedings of the Royal Society B (Open Access).
• Jan 2025 Lecheval V & Theraulaz G. Conditioning a collective avoidance response in rummy-nose tetra. Journal of Fish Biology. (see preprint).
• Jul 2024 Lecheval V et al. Random walks with spatial and temporal resets can explain individual and colony-level searching patterns in ants. Journal of the Royal Society Interface (Open Access).
• Jul 2023 Lecheval V & Mann R Smart self-propelled particles: a framework to investigate the cognitive bases of movement. Journal of the Royal Society Interface (Open Access).
• Apr 2021 Lecheval V et al. From foraging trails to transport networks: how the quality-distance trade-off shapes network structure. Proceedings of the Royal Society B (Open Access).
• Jul 2020 Escobedo R, Lecheval V et al. A data-driven method for reconstructing and modelling social interactions in moving animal groups. Philosophical Transactions of the Royal Society B. Data sets and software Xtract.
• Apr 2018 Lecheval V, et al. Social conformity and propagation of information in collective U-turns of fish schools. Proceedings of the Royal Society B. PDF, supplementary material and data set. Communiqué de presse.
• Mar 2018 Crosato E, Jiang L, Lecheval V, et al. Informative and misinformative interactions in a school of fish. Swarm Intelligence.
• Jan 2018 Calovi D, Litchinko A, Lecheval V, et al. Disentangling and modeling interactions in fish with burst-and-coast swimming reveal distinct alignment and attraction behaviors. PLOS Computational Biology (Open Access).
• Nov 2017 Jiang L, Giuggioli L, Perna A, Escobedo R, Lecheval V, et al. Identifying influential neighbors in animal flocking. PLOS Computational Biology (Open Access). Communiqué de presse.
• Oct 2013 Khuong A, Lecheval V, et al. How Do Ants Make Sense of Gravity? A Boltzmann Walker Analysis of Lasius niger Trajectories on Various Inclines. PLOS ONE (Open Access).

Animal Behaviour Live

I am one of the co-founders of the Animal Behaviour Live initiative, an international online platform promoting sustainable and inclusive events fully broadcasted online on YouTube. We aim to bring together researchers in animal behaviour from all over the world to discuss the latest research and question our academic practices.

We also maintain the Animal behaviour on Mastodon directory. This directory lists Mastodon accounts from animal behaviour scientists (Ethologists, Neuroethologists, Behavioural ecologists, Collective behaviour researchers alike), societies and institutions and offers an easy method to find new profiles and follow multiple accounts at once.

Data sets

The following data sets can be used to reproduce our results, for new research or for pedagogical purposes, for instance in courses aiming to engage students in scientific inquiry using real data. You can refer to the associated research article for details regarding the empirical set-up or the data treatment.

• Apr 2018 Lecheval V, Jiang L, Tichit P, Sire C, Hemelrijk CK, Theraulaz G (2018) Data from: Social conformity and propagation of information in collective u-turns of fish schools.
  This data set contains 2-D trajectories from 68 experiments of single fish and groups of 2, 4, 8 and 10 fish swimming for an hour in a ring-shaped tank filled with 7 cm of water. The corridor was 10 cm wide with a circular outer wall of radius 35 cm and a conic circular inner wall of radius (at the bottom) of 25 cm. Positions of individuals were recorded at 50 frames per second, tracked with idTracker and saved as CSV files. In the ring-shaped set-up, fish schools performed collective U-turns, of interest to monitor the propagation of information. The data set has been analysed in (Jiang L et al., 2017), (Crosato E et al., 2018) and (Lecheval V et al., 2018).
  
  Download data on the Dryad Digital Repository

  

• Oct 2013 Khuong A, Lecheval V, Fournier R, Blanco S, Weitz S, et al. (2013) Data from: How Do Ants Make Sense of Gravity? A Boltzmann Walker Analysis of Lasius niger Trajectories on Various Inclines.
  The experiment consisted of single ants walking freely on a white painting canvas, titled with various inclinations (0°, 20°, 30°, 45° and 60°), in a climatic room with a controlled temperature of 26°C and a relative humidity of 50%. For each inclination and each of 3 colonies, 23 ants were collected from their housing container and picked up in turn. The ants were then filmed until they exited from the canvas frame. From the 50 Hz interlaced video recordings, a custom tracking software extracted the position of the ant at each frame with sub-millimeter precision. These tracked points were finally sub-sampled at 25 Hz.
  Each archive file contains a series of 69 files, one file per ant. Each file contains the data of a trajectory in a tab-delimited text format with 9 columns, corresponding, respectively, to the inclination index, the colony index, the temperature, the humidity, the recording date, the individual index, the rank of the video frame, the corresponding time in second, and the x and y coordinates in meters. Each file starts with a header row labeling this information.
  
  • Download data for null slope
  • Download data for slope 20°
  • Download data for slope 30°
  • Download data for slope 45°
  • Download data for slope 60°

Media coverage

• May 2018 Les mystères des bancs de poissons, Camille Gévaudan, Libération (French)
• Nov 2017 Welke vis volgt welke vis in de school?, Willem Schoonen, Trouw (Dutch)

Education

• 2014-2017 Double PhD degree at the Research Center of Animal Cognition, Toulouse University (France) and the Groningen Institute for Evolutionary Life Sciences, Groningen University (The Netherlands). This PhD project was supervised by Charlotte Hemelrijk (Groningen University, The Netherlands) and Guy Theraulaz (Toulouse University, France). My PhD thesis, entitled Experimental analysis and modelling of the behavioural interactions underlying the coordination of collective motion and the propagation of information in fish schools addressed the questions of coordination of motion and information transfer in groups of fish under internal or external perturbations. Download the thesis.
  
  Received the second prize of the 2018 National PhD Thesis Award in Complex Systems of the Complex Systems Institute of Paris, France
  
  
• 2013-2014 Master programme in Computational Science, Uppsala University, Sweden. Master thesis entitled On collective bandit behaviour supervised by Kristiaan Pelckmans, in Uppsala, Sweden.
• 2011-2013 Master's degree in Ecological Systems Modelling, Toulouse University, France. Master thesis entitled How do the support inclination and the temperature affect the ant motion? supervised by Jacques Gautrais in Toulouse, France.
• 2010-2011 Bachelor of Science in Biology and Environment, Toulouse University, France
• 2008-2010 2-year special undergraduate studies to prepare competitive entrance examinations for admission in engineering schools, École des Métiers de l'Environnement, Rennes, France