The growling grass frog’s call is several short grunts followed by a long, deep growl that lasts for about a second.

Melbourne Water is asking Maribyrnong and Hobsons Bay residents to record calls, including those of the emerald green growling grass frog, using a new app launched just in time for its 15th Frog Census.

Melbourne Water frog expert and Waterwatch co-ordinator Richard Akers said the census was conducted each year to help with conservation efforts.

Local populations of the endangered growling grass frog can be found along the Maribyrnong River and Skeleton Creek and in Newport.

“Because they are endangered, it’s really important we get as much information about these elusive frogs as possible,” Mr Akers said.

“Growling grass frogs start calling at this time of year, and with recent rains they’ve been heard in other areas around Melbourne. They get vocal in the warmer weather, so there’s a good chance you may hear them during a sunny picnic on the banks of the Maribyrnong.”

Mr Akers is urging residents to download the app, visit their parks or local waterways and keep an ear out.

“Every record helps improve conservation efforts,” he said.

To download the app, visit melbournewater.com.au/frogcensus or call 131 722.