When Storm Stanford walks through a flying-fox camp during extreme heat, the noises that she hears are always the hardest to forget.

“One of the worst things is in the aftermath when you’re waiting and you hear the mums calling out for their pups,” the coordinator of the WIRES bat and flying fox team told 9news.com.au.

“During a heat stress event, the animals are all over the place. Afterwards, you see the mums flying around and calling. Some will stop, but others will keep calling because their pup isn’t going to respond.”

Ms Stanford was one of the WIRES volunteers desperately attending to a local bat colony in Campbelltown, in Sydney’s south-west, on Sunday when more than 200 animals were found dead during record-searing heat . Most of them were pups.

Mounds of dead flying foxes in Campbelltown suburb of Sydney. (Facebook/Help Save the Wildlife and Bushlands in Campbelltown) (Help Save the Wildlife and Bushlands in Campbelltown)

To date, about 3000 of the bat species have since died across Sydney, and others across New South Wales and Victoria, claimed by the effects of a dangerous heatwave that moved through the nation’s south-east.

“Heat stress at this time of year wipes out a percentage of the young,” Ms Stanford said.

“It was awful, but it will happen again.”

The scene has been described by volunteers as “unbelievable” as dead bats were found on the ground, while others dangled from trees.

“When you go into a camp in heat stress, all the animals are on the ground because that’s the coolest place they can be. There are piles of bodies – some of them are dead, others are alive,” she explained.

Volunteers worked tirelessly to rescue the local bat colony in Campbelltown. (Facebook/Help Save the Wildlife and Bushlands in Campbelltown) (Help Save the Wildlife and Bushlands in Campbelltown)

A rescued flying fox in Campbelltown. (Facebook/Help Save the Wildlife and Bushlands in Campbelltown) (Help Save the Wildlife and Bushlands in Campbelltown)

“We go around and spray the animals, and those who are alive will hopefully respond by starting to lick the water off themselves.”

Those animals that aren’t responsive but are still alive – most commonly pups – are fed with injectable fluids.

“Then we wait for them to respond. You wind up with animals who are dead and animals who are recovering,” she said.

“In 45+ degree heat, all members battled to save as many as they could without falling in the heat themselves, but with great team work and support they made it through to nightfall,” environmental group ‘Help Save the Wildlife and Bushlands in Campbelltown’ wrote on Facebook .

Four hundred animals from the Campbelltown colony were lost, according to the environmental group’s last count, as volunteers later worked to nurse others back to health.

“We go into the camps the day after and see who has come down and if any animals are still around. The animals that are hanging low are not in a good way,” Ms Stanford said.

The count adds to a total of 1000 flying foxes reported dead from three camps in Western Sydney, according to preliminary data from the group released yesterday.

Up to 500 bats have died in Emu Plains and another “couple of hundred” in Singleton.

Across the Hunter Region, a total of 2000 deaths were reported from four camps since the weekend, including 800 in Raymond Terrace, 600 in Tenambit and “many hundreds” dead in Blackalls.

Fifty-three flying foxes have also died in Bomaderry Creek since Sunday.

Ms Stanford said the vulnerable species has survived worse years.

“We were quite lucky given the temperatures we experienced … it’s not as bad as past years,” she said.