Do birds & frogs sing differently in the city?

Wildlife can use sound to communicate in many different ways but, more often than not, they may distinctive sounds to help find a mate. One of the things I've notice while recording in urban wetlands is the large amount of noise pollution caused by traffic, industry and other human activity. I know there is a dramatic reduction in frog calling activity during evenings when the wind is strong. One field trip on the south coast we recorded about 8 species of frog calling on the first night but one the second night the wind was much stronger and we only recorded 2 frog species. How are these animals responding to "human-made" noise?

There has been some media interesting in a recent Melbourne University study that has indicated that urban noise is changing the calls of some bird species. The soon to be published study titled "Geographically pervasive effects of urban noise on frequency and syllable rate of songs and calls in silvereyes (Zosterops lateralis)" by Potvin, Parris & Mulder reports on the adaptation of birds to urban environments by calling at higher frequencies. You can read the abstract here.

It also reminded me of this paper reporting a change in the frequency of frog calls in habitats close to traffic from 2009. That paper reporting on changes in frog calls, "Frogs Call at a Higher Pitch in Traffic Noise" by Parris, Velik-Lord & North is available here Turns out it is one of the same researchers, K Parris, involved in both projects!

I guess what the work of these researchers is showing is that our natural environment can be influenced as much, perhaps, by noise pollution as other forms of pollution. While bird calls may be shifting as a result of learnt behaviours, the change in frogs call may be reflecting an evolutionary shift in animals adapted to urban environments. I'll be keen to follow the continuing work of Parris and her collegues.

Cam