Collective turns in jackdaw flocks: kinematics and information transfer

Abstract

<jats:p>The rapid, cohesive turns of bird flocks are one of the most vivid examples of collective behaviour in nature, and have attracted much research. Three-dimensional imaging techniques now allow us to characterize the kinematics of turning and their group-level consequences in precise detail. We measured the kinematics of flocks of wild jackdaws executing collective turns in two contexts: during transit to roosts and anti-predator mobbing. All flocks reduced their speed during turns, probably because of constraints on individual flight capability. Turn rates increased with the angle of the turn so that the time to complete turns remained constant. We also find that context may alter where turns are initiated in the flocks: for transit flocks in the absence of predators, initiators were located throughout the flocks, but for mobbing flocks with a fixed ground-based predator, they were always located at the front. Moreover, in some transit flocks, initiators were far apart from each other, potentially because of the existence of subgroups and variation in individual interaction ranges. Finally, we find that as the group size increased the information transfer speed initially increased, but rapidly saturated to a constant value. Our results highlight previously unrecognized complexity in turning kinematics and information transfer in social animals.</jats:p>

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

“…Traditionally, stereoscopic set-ups have used regular (planar) cameras for the three-dimensional tracking of flocking or swarming animals, such as mosquitoes [ 3 ], midges [ 4 , 16 , 17 ] or birds [ 18 – 22 ], which has provided considerable insights into the mechanisms involved in collective dynamics, for example the structure of interactions [ 17 , 19 , 23 ] or propagation of information [ 18 , 22 ]. Over the past few years, however, 360-degree cameras (or 360-cameras) have started to be used widely, notably in computer vision [ 24 ].…”

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

“…Traditionally, stereoscopic setups have used regular (planar) cameras for the 3D tracking of flocking or swarming animals, such as mosquitoes [3], midges [4,15,16], or birds [17,18,19,20,21], which have provided considerable insights into the mechanisms involved in collective dynamics, for example the structure of interactions [17,15,22] or propagation of information [20,21]. Over the past few years, however, 360-degree cameras (or 360-cameras) have started to be used widely, notably in computer vision [23].…”

Self-organization in natural swarms ofPhotinus carolinussynchronous fireflies

“…In other words, the distributions of r ij (φ i , φ j ) are broad ( Fig. S3), in stark contrast to bird flocks or human crowds where the time-distance relationship is very narrow [20,21,22,23]. This suggests that local interactions may extend beyond each firefly's immediate geometric vicinity.…”

“…Local interactions have been proposed to be either metric [18], where individuals interact with peers within a certain distance, or topological [19], where interactions occur through a set number of nearest neighbors. In flocks, schools, and crowds, local interactions have been shown to result in a constant-velocity (linear), underdamped propagation of information [20,21,22,23].…”