'Nightmare': Over 2000 flying foxes perish during Victorian heatwave

Dead bats were dropping from trees in Bairnsdale on Friday due to the extreme heat. Credit: Shelly Nundra

More than 2400 flying foxes died from heat stress in Victoria's east during last week's scorching conditions, with conservation groups saying they have never witnessed anything like the "nightmare" event.

In East Gippsland on Friday, grey-headed flying foxes struggling to cope with the sweltering conditions began to drop from trees.

Local police declared the situation a "natural emergency" on Friday afternoon and the Department of Environment, Land, Water and Planning quickly closed parts of Bairnsdale's Mitchell River Walking Track to the public.

At least 2000 flying foxes are estimated to have died in East Gippsland during the scorcher. Credit: Shelly Nundra

The flying foxes were dropping from trees next to the Mitchell River. Credit: Shelly Nundra

In Bairnsdale, where the department estimates 1513 flying foxes died, temperatures reached 45.8 degrees on Friday. Another 900 bats died at a colony in Maffra, 60km west of Bairnsdale.

The nationally-protected species is highly nomadic and colonies vary greatly in size depending on the time of year.

However, authorities believe there were about 5000 flying foxes roosting in Bairnsdale last week, meaning a third died due to Friday's heat.

Lisa Roberts, spokeswoman for Friends of Bats and Habitat Gippsland, said they had been concerned in the lead-up to Friday.

"At 9am they were starting to move down lower in the trees and were fanning themselves. But by 1pm they had gone into severe heat stress, the final stage," she said.

"We started trying to spray the clumps but by then there were dead bats dropping out of trees, dying bats all over the road... I've never seen anything like it."

Bats fly over Bairnsdale in the days before the heatwave. Credit: Lisa Roberts

She said an incident control team from DELWP arrived about 6pm, but "it was too late by then".

"It was just a nightmare ... It was mostly euthanising and bagging them," she said. She believes the department needs to improve the way it responds to similar events by working more closely with local groups.

"We are going to see more of this," she said.

A DELWP spokeswoman said an emergency response was initiated over the weekend in Bairnsdale and Maffra, involving forest and wildlife officers, police, the local council, vets and local wildlife carers.

Bags of dead bats are removed by authorities near the Mitchell River in Bairnsdale. Credit: Shelly Nundra

"Heat stress events are natural and flying foxes have evolved to deal with temperatures in excess of 40 degrees for short periods," she said.

"However, they are not equipped to deal with prolonged temperatures in excess of 40 degrees, especially when the heat is accompanied by low humidity and hot drying winds, as was experienced on January 25."

Lawrence Pope, the president of Friends of Bats and Bushcare, said heat has the same effect on flying foxes as humans. When their core temperature rises, bats become disorientated and can collapse and die of heat stroke.

Spraying them with water can help them cool down. They also need to be separated and "de-clumped" so they aren't heating up in a pile.

"The species is feeling the effects of climate change," he said.

"The forecast or climate projections show these weather events will get more and more frequent and severe. I don't know if we can save this species. Some scientist think it will be extinct by 2050."

A volunteer helps Parks Victoria staff on Friday to cool the bats by spraying water at Yarra Bend Park in Melbourne. Credit: Parks Victoria

In Melbourne, the biggest flying fox colony resides at Yarra Bend Park.

On Friday, Parks Victoria staff and volunteers sprayed the heat-stressed bats but a few hundred bats died.