Thousands of flying foxes have died due to the severe heatwave sweeping south-east Australia last week. The event is the largest mass death of these bats since the black summer fires. Extreme heat hit camps in South Australia, Victoria, and New South Wales, with grey-headed flying foxes, a vulnerable species, worst affected. Tamsyn Hogarth of Melbourne’s Fly by Night Bat Clinic said volunteers found thousands of dead bats at Brimbank park and hundreds more at Yarra Bend and Tatura camps. They rescued dozens of pups clinging to their dead mothers. Hogarth warned, “These orphans will slowly die of heat stress, starvation or predation if they aren’t found.” The heat was brutal, especially in trees with less shade and the hot clay riverbanks. Experts estimate 1,000 to 2,000 flying foxes died in South Australia, thousands in Victoria, and up to 1,000 in New South Wales. Western Sydney University’s Professor Justin Welbergen noted, “Temperatures over 42 degrees are known to cause mortality in flying foxes, sometimes at biblical scales.” The heatwave was the worst mass die-off since 2019-20, when 72,000 flying foxes died over eight heat events. The last week’s heat pushed Adelaide to 43°C on several days. Melbourne and Sydney also saw temperatures above 42°C, with some suburbs reaching mid to high 40s. The impact is twofold: direct heat stress and harder times finding food as nectar sources drop. Mothers and pups suffer the most, hurting population recovery. Dr Wayne Boardman from the University of Adelaide explained, “Above 42C, dehydration and heat stroke made it physiologically very difficult for animals to survive.” People are urged not to rescue bats themselves but to contact wildlife groups. Lisa Palma, CEO of Wildlife Victoria, said her team expanded emergency response and sent vets to critical flying fox colonies. She added, “Heat events like this can be catastrophic for native wildlife.” Welbergen called flying foxes “canaries in the coal mine” for wider wildlife challenges posed by global warming. Volunteers face heavy workloads and resource shortages. Hogarth said, “We were already at breaking point and dreading what the hot weather would bring - now our worst fears have been realised.”