Fig. 1

Sonograms showing the songs (A,B) and calls (C,D) of four Dupont’s larks. Boxes indicate the different song and call types identified within each individual. The classification of songs and calls was based on spectrogram morphology, temporal patterns, frequency characteristics, and number of notes. For example, song type S1 and call type C1 each appear twice in sonograms A and C, respectively. The population where each sonogram was recorded is indicated in brackets after the corresponding capital letter, according to the ID column in Table 1.