Effects of urban noise on song and response behaviour in great tits

Abstract

Acoustic communication is fundamental in avian territory defence and mate attraction. In urban environments where sound transmissions are more likely to be masked by low-frequency anthropogenic noise, acoustic adaptations may be advantageous. However, minor modifications to a signal could affect its efficacy. While recent research has shown that there is divergence between songs from noisy and quiet areas, it is unknown whether these differences affect the response to the signal by its receivers. Here, we show that there is a difference in spectral aspects of rural and urban song in a common passerine, the great tit Parus major, at 20 sites across the UK. We also provide, to our knowledge, the first demonstration that such environmentally induced differences in song influence the response of male territory holders. Males from quiet territories exhibited a significantly stronger response when hearing song from another territory holder with low background noise than from those with high background noise. The opposite distinction in response intensity to homotypic versus heterotypic song was observed in males from noisy territories. This behavioural difference may intensify further signal divergence between urban and rural populations and raises important questions concerning signal evolution.

Geographically pervasive effects of urban noise on frequency and syllable rate of songs and calls in silvereyes (Zosterops lateralis)

“…However, noise in natural environments covers a wide frequency range [33] and therefore may not exert a strong directional selection pressure for higher frequencies across multiple geographical locations in the same way as urban noise, which is consistent between cities, and is almost exclusively concentrated in the lower frequency bands. to habitat [15,34]. However, frequency shifts in urban environments have also been observed in taxa that do not learn their vocalizations, such as non-passerine birds [23], and the southern brown tree frog (Litoria ewingii; [21]).…”

A phantom road experiment reveals traffic noise is an invisible source of habitat degradation

“…During energetically demanding periods in a bird's life, increasing vigilance can reduce survival because of increased starvation risk (27). In contrast to song masking, which can be partially overcome by frequency shifting (28), release from masking is not possible for auditory cues necessary for aural vigilance (7). With limited auditory information, animals must resort to other methods such as visual scans to compensate for the increase in perceived predation risk, perhaps driven by masking of communication calls and predator-generated sounds (26,29).…”

Bird song and anthropogenic noise: vocal constraints may explain why birds sing higher-frequency songs in cities

“…they increase the amplitude of their vocalizations in response to an increase in background noise (reviewed in [19]), which is used to communicate in the presence of anthropogenic noise [20]. It is also often observed that birds sing at higher frequencies at noisy locations [21][22][23][24][25], which is probably the result of vocal plasticity [26][27][28].…”