Fig. 4

Song traits of African and European stonechats with a) song rate, b) element rate per song, and c) peak frequency. European stonechats sang with a higher song rate, element rate, and peak frequency during the mating period than African stonechats. Filled points and error bars represent back-transformed posterior means and 95% credible intervals. Sample sizes are displayed below error bars and are similar for element rate and peak frequency. Open symbols represent data points of individuals from different populations