In communication, animals often use complex signals with different traits carrying different information. In the song of songbirds, such traits can either be structural patterns or temporal patterns. Most structural song patterns such as the use of rapid broadband trills are exposed to stronger spectral degradation than temporal patterns such as song overlapping. Consequently trills may better function as close range signals whereas song overlapping may also maintain its function at longer distances. Here, we investigated in nightingales (Luscinia megarhynchos) whether the signal value of song overlapping and the use of rapid broadband trills changes when broadcasted from different distances using nocturnal playbacks. Males’ responses indicate that males perceived close intruders as a stronger threat, regardless of the song traits that were used to signal aggressive singing. However, males did not adjust their responsiveness to the degradation level of the different traits. These findings suggest that rapid broadband trills are used during close range interactions in order to define a repelling area. Moreover, the results suggest that strongly degraded traits can maintain their function even at far distances.
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