Figure 5

Typical sonograms of the calls of the highland Zosterops poliogaster (A) and lowland Zosterops abyssinicus (B), displaying the parameters analysed for this study: 1: starting frequency (typically congruent with lowest frequency); 2: first peak (typically congruent with highest frequency); 3: highest frequency; 4: end-frequency (sometimes congruent with lowest frequency); additional characters measured were total call duration (seconds) and frequency range (highest to lowest frequency).