Changing Tune

Image credit: (copyright) Sergei Elkin

Noise is often a problem for many of us living in large cities. Yet, high noise levels may affect more than just a good nights sleep for some urban animals.

Recent research published in Behavioural Ecology has suggested that noise pollution is affecting components of bird song in the European Robin. In this species the male is very territorial and uses his song to warn away competing males, and serenade potential mates. 

Although it is sexually selected, bird song is a fairly flexible trait. This means that components of an individuals song can be altered in frequency, complexity or timing and so on. High levels of background noise in the environment can reduce the transmission of bird songs and make them harder to hear. 

Image credit: Roger Butterfield 

Through comparisons of individual bird songs with varying levels noise exposure, the researchers determined that males in the loudest areas had to change components of their songs in order for them to be heard. In particular, minimum frequency at which the males sang was increased by high levels background noise. However changing one component had a knock-on effect for other song components. Increasing the minimum frequency led to reductions in song length, rate and complexity of the song. 

As the elaborate nature of bird song is well documented for attracting mates, comprises in song quality caused by human noise pollution could reduce the reproductive success of males living in noisy areas. 

Find Out More:
BBC Earth News - How noise pollution is affecting many different species

Sources:

• MONTAGUE, M. J., DANEK-GONTARD, M. & KUNC, H. P., 2012. Phenotypic Plasticity affects the response of a sexually selected trait to anthropogenic noise. Behavioral Ecology. 342 - 348