Figure 1. Similarities between calls of individuals at (a) 1 week and (b) 5 weeks old. Plot of the first principal component (PC1) against the second principal component (PC2) extracted from the principal components analysis (PCA) including all vocal parameters. Each dot corresponds to the PCA centroid of an individual. Kids of the same group (N = 23 kids, four groups, delimited with lines) are indicated with the same shape and same colour and kids born from the same mother (full siblings) are indicated with the same number (N = 12 mothers). The closer two individuals are on the plot, the more similar their call structure is.