Nightingales respond more strongly to vocal leaders of simulated dyadic interactions

Although vocal interactions in songbirds have been well studied, little is known about the extent to which birds attend to their conspecifics' interac tions. Attending to others' interactions can provide valuable information s ince vocal interactions are often asymmetrical and can reflect differences in the state or quality of the signallers. Playback experiments with simula ted dyadic interactions showed that male territorial nightingales (Luscinia megarhynchos) attend to asymmetries in interactions and respond more stron gly to rivals that overlap the songs of their counterpart. In order to test if nightingales respond differently to two interacting rivals that are alt ernating songs asymmetrically (with leader-follower roles), we simulated an interaction using a dual-speaker design. Subjects discriminated between th e simulated singing strategies and responded more intensely at the loudspea ker playing the preceding songs. This suggests that individuals whose songs precede in an interaction when there is no acoustic overlap are perceived as more serious rivals. Intense responses to the preceding songs compared w ith intense responses to the overlapping (non-preceding) songs in a previou s study also indicate that discrimination is not the result of one specific proximate cue such as greater attention to the first- or last-heard stimul us. Thus, these results provide further evidence that by listening to asymm etries in conspecifics' vocal interactions, receivers can obtain valuable i nformation on their relative differences.