"I get called the 'frog whisperer' because they love when I imitate the frog calls, they just love it," The Frogwatch ACT coordinator said.

"There's one if you go into the Australian Botanic Gardens that just goes bonk-bonk-bonk. There's a whistling tree frog that goes cree-cree-cree-cree-cree."

Ms Hoefer is teaching others how to speak frog too ahead of the ACT's largest citizen science project, Frogwatch's annual census.

Hundreds of Canberrans will squelch around the city's wetlands and ponds later this month in search of their unique croaks amongst the bush cacophony.

Canberra's frog population has lost much of its diversity in the past 50 years but learning to decipher their whistles, ratchets, and bonks can help FrogWatch ACT find pockets where the pint-sized amphibians cling on, Ms Hoefer said.

There are now nine common species in the ACT and listening to their croaks in the darkness is easiest way to collect information on the territory and prevalence of the nocturnal species.

"It's much easier to hear them in the dark. You'd have to spend hours turning logs and looking because the way their skeleton is they can squeeze into the tiniest of crevices under logs, under bark and between rocks," Ms Hoefer said.

"Often you can stand right on top of one virtually but you can't see them because they're relatively small and very camouflaged."

While there are more frogs hiding around you than you probably think there are, Ms Hoefer said the nasty chytrid fungus and habitat loss has seen once robust species become scarce.

"Many of our once common species in the ACT are now extinct within the ACT or have dramatically declined within their range," Ms Hoefer said.

"What was common in the 80s is now gone, like the green and golden bell frog for example, and so they're not here anymore and we assume they're totally common, they're almost a pest, they're everywhere, then all of a sudden there's none."

Ms Hoefer said without frogs, many ecosystems would just crumble.

"In Bangladesh they exported all of the frogs out of the rice paddock to France for the food trade and after a few years the birds started to go, there were not as many snakes in that area either, then they had much more outbreak in malaria because there were so many more mosquitos around, they had a decrease in the rice yield because those plants were not fertilised in the rice paddocks."

Frogs are also like the "canary in the mine" for environmental degradation, Ms Hoefer said.

"Because frogs have a two-phase life cycle they're a real environmental indicator species for aquatic as well as for terrestrial habitats so that's why they're often used in scientific evaluations of habitat quality of certain areas. Every chemical that's in the water is in that animal virtually," she said.

Taking stock of frog numbers once a year by listening to their calls is one way to safeguard their special place in our environment.

"Sometimes I get farmers who say 'I've been listening to these frogs for years and now I've had some training I finally know what kind of species are out there'," she said.

To sign up to a Frogwatch ACT seminar, head to: www.ginninderralandcare.org.au/frogwatch/frogwatch-census.