Urban noise affects multiple aspects of avian song (#119)
One of the main urban effects on wildlife habitats is increased degree of habitat heterogeneity at a micro-geographic level, which leads to such effects as reduced habitat size, altered community structure, and changes in light and acoustic conditions. Little is known about how increased variation in habitat conditions at a micro-geographical level affects animal populations. In this study, we use tui, a native New Zealand honeyeater with complex vocalizations, as a model to investigate how variations in the noise level in urban habitats affect song structure and singing behavior of birds. Our results show that tui songs at sites with higher noise levels had higher minimum frequency, higher aggregate entropy, and reduced proportion of trill components within their songs. Tui also reduced the duration of songs and syllable diversity per song at noisy habitats compared to quieter sites within the same suburb. We have also recorded a higher within-site variance in syllable repertoire among individuals in urban sites compared to non-urban sites, suggesting a response to the heterogeneity in noise levels within a site. Bird songs are known to be sexually selected traits. Such urban effects on singing behaviour of song birds are likely to have further implications, such as altering breeding behavior, mating systems and individual fitness; all of which warrant further research.