Fig. 1. Experimental design. (A) Training (grey arrows) and test situations in Experiments 1 and 2. Filled circle, nest entrance; open circle, close vicinity of the nest; filled black square, feeder, nest-to-feeder distance, 8 m. Experiment 1 (black arrow): ants were captured at the feeder and released close to the nest entrance; Experiment 2 (red arrow): ants were captured at the feeder and released into the nest entrance. (B) Training (grey arrows) and test situations in Experiment 3. N, natural nest entrance; E, nest entrance on the arena (diameter, 1 m) enforced by a metal tube; F, feeder trap. Experiment 3 (green arrows): ants were released from the feeder trap into the nest entrance and the arena was turned by 180° (lower diagram); PI arrow, walking direction defined by path integration (after a 180° turn of the arena); EC arrow, walking direction defined by arena-specific external cues.