Fig. 2

Experimental design and corresponding figures. A Experimental design showing three sessions of playbacks (one per species played) carried out over 1 day and the effects investigated (blue = species played; green = valence of the sound series; orange = valence of the first sound series of each session; the same color code is used for (B) and (C)). B Equidae’s responses to the playbacks: (a) domestic horse (PC4 scores) and (b) Przewalski’s horse (PC2 scores) responses as a function of the order in which positive and negative sounds (all species combined) were played; (c) Przewalski’s horse (PC3 scores) response as a function of the order in which positive and negative conspecific whinnies were played back; (d) domestic horse (PC1 scores), (e) domestic horse (PC4 scores) and (f) Przewalski’s horse (PC1 scores) responses as a function of the species played back (Tables 1 and 2). C Suidae’s behavioral responses to the playbacks: (a) domestic pig (PC3 scores) responses as a function of the order in which positive and negative sounds (all species combined) were played, (b) wild boar (PC1 scores) responses as a function of the valence of pig grunts played back, (c) domestic pig (PC2 scores) and (d) wild boar (PC3 scores) responses as a function of the species played back (Tables 3 and 4). Boxplots: the horizontal line shows the median, the box extends from the lower to the upper quartile and the whiskers to 1.5 times the interquartile range above the upper quartile or below the lower quartile, open circles indicate outliers and black circles the mean, the lines show the model estimates (continuous line) and 95% confidence intervals (dashed lines)