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WANTED! Eavesdroppers on Red Tree Frog conversations to better understand effects of urbanisation

By: Brittany Mitchell, Category: AMRI, Date: 30 Oct 2018

Recording frog calls with the FrogID app may let us know how they are coping in urban areas.

Litoria rubella

Litoria rubella
Photographer: Jodi Rowley © Australian Museum

I am investigating the effects of urbanisation on our native frogs, in particular how they communicate with each other. Whilst millennials spend their nights swiping right on prospective Tinder dates, female frogs are out listening for calls to find their prospective mates. But the calls that female frogs are listening to from their male counterparts can reveal much more than who is the ‘hottest’ frog at the pond. Frog calls can also let us know how frogs are faring in ever-changing environments, such as urban areas.

Frogs are under immense threat and are rapidly declining across the globe. Urbanisation is a major contributing factor to these declines as vital frog habitats are drastically modified or lost. However, habitat modification is not the only threat posed by urbanisation. Urban areas are also characteristic of increased noise and light pollution. Noise from urban spaces (0 – 3kHz) overlap with the frequencies that most frogs call within and this can negatively impact reproductive success of frog populations, as it’s hard for a frog to be heard over the nearby traffic noise.

But it’s not just noise – some frog species get nervous calling out to their date when there’s a lot of artificial light around and reduce their calling activity. Furthermore, some calls become distorted as they travel through and around buildings. Just imagine all the poor frogs being stood up…

However, frogs may be potentially communicating with their mates by changing their calls. Some frogs might be calling louder (over that of urban noise), or increasing their call rates, whilst others are shifting their call frequencies out of the urban noise range to be heard (calling at a higher pitch). The ability of frogs to alter their calls in response to their new, urban, environment, has largely been documented in other countries, and very little is known whether Australian frogs will behave the same.

To determine whether our native frogs are coping despite urbanisation pressures, I am analysing the calls of the Red Tree Frog (Litoria rubella) from across Australia. This will allow me to work out if our this small (but loud!) frog species is able to persist in cities and urban areas, and if it is adjusting its calls in these environments. It will also greatly influence decisions regarding future conservation of Australia’s frog species.

I need your help! Please use the free FrogID app to record calls of the red tree frogs from both urban and non-urban environments, particularly from NSW – however, calls from anywhere the Red Tree Frog is calling from are greatly appreciated! Not only will you be taking part in Australia’s biggest frog count, but you’ll contribute to our understanding of how urbanisation is impacting frog communication and reproduction.

To hear what the red tree frog sounds like, you can find a recording on the FrogID website. Download the free FrogID app, head out tonight and record some frogs!

Brittany Mitchell - Honours student, AMRI & UNSW