Figure 4.

Examples of 2 interactions. The upper graph in each case shows song types (arbitrarily coded with numbers) versus time, and the lower graph shows the 5-song running total diversity (switching rate × song-type diversity) versus time. Unshared song types are indicated by square markers at the top and bottom of the graphs, all others are shared between both birds; rattle-buzz song types are indicated by “X” markers. The instigator (first approacher) is shown in black and the responder (second approacher) is shown in gray. (A) In this interaction, the instigator was the first to retreat. He sang with a higher diversity throughout the interaction and sang many unshared songs. (B) In this interaction, the instigator was the persister. Both birds grunted at level 3 during the interaction between 300 and 500 s, and the relative song diversities of the birds changed afterward, with the instigator singing more repetitively.