Directional correlation delay vs. position in the group. Each boxplot represents the distribution of directional correlation delays τ
∗ over simulated trajectories. The box on the left indicates trajectories in which the focal individual was in front; while the box on the right indicates those where the focal individual was behind. In our convention, positive values of the correlation delay τ
∗ indicate that the focal individual anticipates the changes of direction of its partner. When the individuals fly in a front-back configuration, measures of directional correlation indicate that the individual in front anticipates the turns of its neighbour. Left Individuals flying in a front-back configuration, temporal autocorrelation of the noise is short (C
=20 steps); 120 simulated trajectories. Right Same simulation parameters as for the figure on the left, but with longer temporal autocorrelation of noise (C
=100 steps). Note that in this case the variability is extremely reduced and τ
∗ was equal to ±1 in all but one simulation.