Across Australia, more than 1,000 and 600 people have reported finding sick or dead frogs. Each report often describes dozens of dead frogs, putting the grim tally in the thousands. It's the second winter in a row, and scientists are racing to find the cause. Greg Navarro has more from Sydney.

Much of biologist Jodi Rowley's work these day involves examining frogs, dead frogs.

"So somebody has zip locked them and frozen them for us."

Hundreds of them stored in freezers at the Australian Museum, where Rowley is looking for clues.

JODI ROWLEY Curator, Frog Biologist, Australian Museum "It was May, June of last year that I realised that things were not quite right in the frog world."

About what's killing them.

JODI ROWLEY Curator, Frog Biologist, Australian Museum "It was really infuriating, really frustrating at the time because all these frogs were dying and we were in lockdown. So I was not able to get out, investigate the health of frog populations and so that is why we had to do a call to action."

People were asked to use the museum's Frog ID app to identify the dead frogs they were finding around their homes and neighbourhoods and the sounds of specific species that were suddenly missing.

KARRIE ROSE Veterinary Pathologist, Taronga Conservation Society "In this event we've really had the public come to the party. They love their frogs, they are distressed to see sick and dead frogs round their homes and when they are going out for a walk."

Frogs have come under increasing threats here because of several factors including bushfires, floods and loss of habitats.

The mystery deaths are happening during the winter when frog's immune systems slow down. More than 40 species have been impacted across the country.

JODI ROWLEY Curator, Frog Biologist, Australian Museum "We certainly know the number one suspect, the amphibian chytrid fungus, is a part of it. So most of the frogs that people collected had the amphibian chytrid fungus on their skin, and this is a type of fungus that eats the keratin on the frog's skin and frogs use their skin for drinking and breathing so it really is their Achilles heel."

GREG NAVARRO Sydney "But the fungus wasn't found in all of the frogs that were collected in places just like this, and scientists say in some of the ones that did have it, the fungus wasn't at the kind of level that you would expect to kill a frog."

Australia has already lost four frog species to extinction and scientists say the latest event poses a threat to entire ecosystems.

KARRIE ROSE Veterinary Pathologist, Taronga Conservation Society "If we lose the frogs we face the potential collapse of all of those ecosystems as we face increased numbers of all of the things frogs eat, and decreased numbers of all of the things that eat frogs."

JODI ROWLEY Curator, Frog Biologist, Australian Museum "I'm worried that this is a bit of a precipice and our frogs aren't going to recover from this."

Which is why Rowley, other scientists, and the public are working together to give these resilient creatures a chance survive before it's too late. Greg Navarro, CGTN, Sydney.