Figure 1.

Box-and-whisker plots across treatments representing: (a) the mean size of largest subgroup, (b) the mean polarization score across treatments, (c) the mean polarization score across small and large subgroups, (d) the percent shoal under vegetation in the presence and absence of predator cues and (e) number of bites at worms. Each dot represents the average over one session of four sessions per group (a–c) or the average over all sessions (d) or the frequency of a unique group (e). The different letters (‘a’ and ‘b’) placed above the boxes represent significant differences between the treatments. The letters ‘ab’ indicate that the treatment is comparable to treatments ‘a’ and ‘b’. CT, control treatment; PT, predator treatment; PVT, predator vegetation treatment; VT, vegetation treatment. Comparisons were performed using Tukey’s HSD test (sample size: mean size of largest subgroup, mean polarization score: N_CT = N_PT = 45 shoals; N_VT = N_PVT = 30 shoals; p < 0.05).