Figure 4.

Box plot showing that: (a) the overall frequency of aggression are significantly higher than in piglets lower wild boar hybrids for the whole period (Mann–Whitney exact test; p = 0.017); (b) aggression hourly frequencies (age periods: T₁ = 6–20 days, T₂ = 21–35 days, T₃ = 36–50 days) are higher in piglets in T₃ (Mann–Whitney exact test; p < 0.001) but not in the other periods. No variation was observed across periods (T₁–T₃) in both hybrids and piglets (Friedman’s test; p = ns). Horizontal line: median value; box: interquartile range; vertical line: minimum and maximum values in the data. NS = non-significant, * = p < 0.05, *** = p < 0.001.