Extended Data Fig. 5: Alignment of movement directions between birds during flocking flight.
For four flocking flight sessions (session #2, #5, #8, and #13), correlation coefficients between movement directions of two birds in a pair are represented by grey lines for each of the 15 possible combination of birds. The mean correlation coefficient is indicated by the thick black solid line. The thin dashed black line marks the zero line. Red dots indicate time points at which movement directions were significantly aligned between the majority of birds (that is the mean correlation coefficient was larger than 0.3 and the mean p value was smaller than 0.05). In the freeze frame of the footage taken with Camera 1, the spatial positions corresponding to the time points marked by red dots in the panel above are shown for all flock members. Colored circles indicate the birds’ current positions and the colored diamonds indicate the birds’ positions at the three preceding time steps. Note the alignment of movement directions between all birds within this time period. Colors indicate bird ID. Wind direction is perpendicular to the plane of the image.
