Fig. 2. Gradual change in trajectories with 45° separation between F1 and F2. (A) The trajectories of ants (N=6) after the feeding site was switched to F2. Paths are grouped by run number. The grey area is the triangle with vertices S, F1 and F2. (B) The initial direction of each path was categorised as F1, F2, intermediate or other. The first three categories are 22.5° wide as shown in the legend. The `other' category represents trajectories that fall outside this range. Stacked bar charts show the change in proportions of each category with run number (N=6; n=32, 60, 46, 37). N, number of ants; n, number of trajectories. This convention is followed throughout. (C) Distribution of headings for all post-switch trajectories (N=6; n=175). (D) Scatter plot showing the change in length of the initial segment plotted against number of trials after the switch. The length of this initial segment was defined by the distance between the start and the location of the first obvious turn determined by eye. Independent observers agreed closely on the presence and location of the first obvious turn in a trajectory. Bars show means and 95% confidence intervals for bins of 10 runs, as in B. The ratio of trajectories containing distinct turns was 100%, 92%, 88% and 56%, respectively, for the four bins.