Raging fires have burnt more than 400,000 hectares across Victoria, destroying more than 700 structures and killing thousands of livestock and native animals.
The fires have hit an array of diverse ecosystems from grasslands in central Victoria to forests in the Otways and the Big Desert Wilderness Park in the state's far northwest.
A huge variety of wildlife, plants and ecosystems had been affected, with even typically resilient species showing signs of impact, Deakin University's Euan Ritchie said.
"Wildlife populations and habitats are still recovering from previous fires (so) to have another severe fire in close succession, that obviously put really heavy strains (on them)," the professor of wildlife ecology and conservation said.
"We often think of Australian animals and plants and ecosystems as being relatively resilient because they've evolved and adapted to fire over a long time.
"But if we keep seeing these events happening too frequently ... it will be death by 1000 cuts for some species."
Significant fires continue to burn in Longwood and Walwa, with the Victorian Farmers Federation estimating statewide livestock deaths at 16,500, made up mainly of sheep.
Ruffy CFA volunteer Daryl Otzen - who battled the Longwood blaze - told AAP the loss of animals was "astronomical".
Conditions became so intense that birds attempting to fly away started falling from the sky, he said.
It's not yet known how many wild animals had been affected, but there is concern for a population of dingoes living in Big Desert, along with long-footed potoroos in the state's east.
But it's not only animals on land that worry experts but also those in water.
"One that's often missed in fires is that although they burn on land, heavy rainfall events following the fires can wash ash into waterways," Prof Ritchie said.
"That can impact native fish species, frogs and crayfish - many that are threatened species in Victoria."
Wildlife Victoria said its emergency hotline had been inundated with calls, and last Friday was its busiest day on record, with 1135 calls for help.
"Sadly, given the ferocity and scale of the recent fires there is likely to be a substantive loss of wildlife lives," CEO Lisa Palma told APP.
"We are working our hearts out absolutely around the clock."
Wildlife vets and support staff are deployed at the state's largest grey-headed flying fox colony in Yarra Bend this week, where heat stress is often fatal.
Meteorologist Angus Hines said significant widespread rainfall, heavy winds and thunderstorms were forecast for Victoria's southeast during the next few days.
But crucially, the key firegrounds of Walwa and Longwood are only expected to receive up to 10mm of rain.
"It's not enough to put out any ongoing bushfires," Mr Hines said.
"We could potentially see some gusty, strong southeasterly winds pushing across those fire grounds and maybe making those fires flare up once again."
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