In trial 1, the weighted mean of success ratio of attacks was 37.28 % (±3.18, SE). Juvenile was unskilled at scale-eating at first. And then, the success ratio of predation was rapidly increased with repeated trials (Fig. 3a; Spearman’s rank correlation, ρ=0.332, p=0.003). When the success ratio of predation was compared between preferred side attack (i.e., lefties attacking the left flank and vice versa) and non-preferred side attack, the preferred side attack achieved higher predation success over the non-preferred side attack (Fig. 3b; Wilcoxon rank sum test: z=2.579, p=0.010).
