Figure 2.

Flock count (a), the number of individual birds in the recording volume at a particular time, (b) flock angular momentum, and (c) the cumulative entry of birds into the chimney. Flips in the angular momentum sign denote reversals in the circling direction. The four highlighted slices were used in the network analysis and related metrics given in table 1. Gaps in the data occurred when the cameras closed one movie file and began another during recording.