Biology subjects

Sarfati, R.

Publications and source records attributed to Sarfati, R..

3 recordsLinked to original sources

bioRxiv2021

Calibration-free 3D reconstruction of firefly trajectories from 360-degree cameras

Over the past few decades, progress in animal tracking techniques, from large migrating mammals to swarming insects, has facilitated significant advances in ecology, behavioural biology, and conservation science. Recently, we developed a technique to record and track flashing fireflies in their natural habitat using pairs of 360-degree cameras. The method, which has the potential to help identify and monitor firefly populations worldwide, was successfully implemented in various natural swarms. However, camera calibration remained tedious and time-consuming. Here, we propose and implement an algorithm that calibrates the cameras directly from the data, requiring minimal user input. We explain the principles of the calibration-free algorithm, and demonstrate the ease and efficiency of its implementation. This method is relatively inexpensive, versatile, and well-suited for automatic processing and the collection of a large dataset of firefly trajectories across species and populations. This calibration-free method paves the way to citizen science efforts for monitoring and conservation of firefly populations.

animal behavior and cognition↗

bioRxiv2021

Self-organization in natural swarms of Photinus carolinus synchronous fireflies

Fireflies flashing in unison is a mesmerizing manifestation of animal collective behavior and an archetype of biological synchrony. To elucidate synchronization mechanisms and inform theoretical models, we recorded the collective display of thousands of Photinus carolinus fireflies in natural swarms, and provide the first spatiotemporal description of the onset of synchronization. At low firefly density, flashes appear uncorrelated. At high density, the swarm produces synchronous flashes within periodic bursts. Using three-dimensional reconstruction, we demonstrate that flash bursts nucleate and propagate across the swarm in a relay-like process. Our results suggest that fireflies interact locally through a dynamic network of visual connections defined by visual occlusion from terrain and vegetation. This model illuminates the importance of the environment in shaping self-organization and collective behavior.

animal behavior and cognition↗

bioRxiv2020

Spatiotemporal reconstruction of emergent flash synchronization in firefly swarms via stereoscopic 360-degree cameras

During mating season, males of synchronous firefly species flash in unison within swarms of thousands of individuals. These strongly-correlated collective displays have inspired numerous mathematical models to explain how global synchronous patterns emerge from local interactions. Yet, experimental data to validate these models remains sparse. To address this gap, we develop a method for three-dimensional tracking of firefly flashes, using a stereoscopic setup of 360-degree cameras. We apply this method to record flashing displays of the North American synchronous species Photinus carolinus in its natural habitat as well as within controlled environments, and obtain the 3D reconstruction of flash occurrences in the swarm. Our results show that even a small number of interacting males synchronize their flashes; however, periodic flash bursts only occur in groups larger than 15 males. Moreover, flash occurrences are correlated over several meters, indicating long-range interactions. While this suggests emergent collective behaviour and cooperation, we identify distinct individual trajectories that hint at additional competitive mechanisms. These reveal possible behavioural differentiation with early flashers being more mobile and flashing longer than late followers. Our experimental technique is inexpensive and easily implemented. It is extensible to tracking light communication in various firefly species and flight trajectories in other insect swarms.

animal behavior and cognition↗