Bursts of white noise trigger song in domestic Canaries

Acoustic communication is fundamentally constrained by noise. In birds, the masking of mating signals (songs) may reduce fitness and, hence, they have evolved various mechanisms to maintain communication in noise. One of these tactics is the adjustment of song timing to avoid overlap with masking sounds, but previous studies yielded contrasting results regarding the occurrence and magnitude of this behavioural plasticity. Here, we investigated how temporal noise avoidance varies with noise intensity. We exposed singing Canaries (Serinus canaria) to playbacks of masking noise of varying amplitude [60-80 dB(A) SPL]. Contrary to our prediction, the birds did not shift song onsets to the silent intervals between noise bursts at high noise amplitudes, nor did they increase singing outside the playback period. Rather, we found that noise generally triggered the onset of song: the Canaries preferentially sang during the noise bursts independent of the noise amplitude. This behaviour is somewhat paradox because it leads to the most unfavourable signal-to-noise ratios. Our results, together with findings from the current literature, indicate marked species differences in the noise-induced song plasticity of birds. Therefore, we suggest a more comprehensive conception of noise that incorporates both supressing and stimulating effects.