Self-organization in natural swarms of Photinus carolinus synchronous fireflies

Abstract

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.

Statistical analysis reveals the onset of synchrony in sparse swarms of Photinus knulli fireflies

“…Importantly, synchronizing respondents were primarily situated in the 1-10 m range, as correlations vanish at larger distances. This is in line with previous findings that synchronizing information propagates only at short range [15].…”

“…Owing to initial adjustments and varying environmental conditions (rain, transient flooding), three full datasets of stereoscopic recordings were eventually obtained (7, 9, 10 August, about 150 min each). Recordings were obtained as described previously [ 15 ] from two Sony α 7R4 cameras set at 60 frames per second (fps) and mounted with a wide-angle lens. Hence, the time resolution of our experiments was 17 ms. Video processing and data analysis were performed with Matlab.…”

“…These observations did include the occurrence of synchrony. Beginning in the early 1990s, Eastern US synchronizing counterparts Photinus carolinus and Photuris frontalis have received ample attention from scientists [ 8 ], bringing videographic evidence to characterize the occurrence [ 9 , 10 ], mechanisms [ 11 , 12 ], possible function [ 13 , 14 ] and modalities of synchronous patterns [ 15 ]. In parallel, this renewed interest in firefly synchronization motivated numerous developments of mathematical and computational models [ 16 – 18 ].…”

Emergent periodicity in the collective synchronous flashing of fireflies

“…Secondly, it is possible that the swarm bu↵ers against unusual perturbations. More than finite-size e↵ects, the main caveat here is that the swarm is not all-to-all connected, as we showed previously (9). Therefore, the e↵ective N would be much smaller than the swarm size, and correspond more appropriately to the number of active fireflies in each other's field-of-view.…”

Chimera States among Synchronous Fireflies

“…Nonlocal interactions, designating weaker or less likely coupling at increasing distances, are the most adequate to produce chimeras [11]. They also reflect a probable social structure in firefly swarms, as supported by simple considerations regarding the extent of line-of-sight interactions as well as prior results in a different synchronous species, Photinus carolinus [18].…”