Figure 4: Parameters measured for analyses of loud calls, smack-whistles, and whistles. In points (A–E) indicated in the spectrograms, frequency and time parameters were measured and used for calculating additional parameters. For analyses of loud calls, we used start (A frequency), bend (B frequency), min (C frequency), middle (D frequency), whistle FM (A-B frequency modulation), smack FM (B–C frequency modulation), centre FM (B–D frequency modulation), whistle duration (A–D duration), smack duration (B–C duration), centre duration (B–D duration), and duration (d). For analyses of smack-whistles and whistles, the following parameters were used: start (A frequency), second peak (D frequency), bottom (G frequency), 1st part FM (A–G frequency modulation), 2nd part FM (G–D frequency modulation), whole FM (A–C frequency modulation) (only in smack-whistles), 1st part duration (A–G duration), 2nd part duration (G–D duration), whistle duration (A–D duration), and duration (d).