Fig. 1. Route shapes are influenced by landmark position. (A) Ants were trained to go from a start position at one end of a large indoor arena to a feeder 3 m away at the other end. A black cylinder was placed either to the left or to the right of the direct path. (B) Ants headed to the left of the direct path (grey band) when the cylinder (filled circle) was on the left. Each dash marks the point of intersection of one trajectory with a semi-circle centred on the start with a radius of 20 cm, 40 cm, 60 cm or 80 cm [n (number of trajectories)=101, N (number of ants) =10]. Open triangles show the mean heading at each distance. (C) Ants tended to head to the right when the cylinder was on the right (n=136, N=14). Two ants were atypical and headed away from the cylinder; their trajectories were excluded from subsequent analysis. The grey band indicates the direct path from start to cylinder. (D) Trajectories of one ant trained with the cylinder on the left and (E) trajectories of one ant trained with the cylinder on the right.