In January 2026, a series of extreme heatwaves across South-Eastern Australia caused one of the worst mass mortality events for flying foxes since the 2019-2020 Black Summer, killing thousands of these vital bats and bringing these vulnerable species closer to extinction.
According to a report by World Weather Attribution (WWA), the intense January 2026 heatwave was made five times more likely by human-caused global heating, with similar occurrences now expected about once every five years.
Grey-headed flying foxes (Pteropus poliocephalus), listed as vulnerable under Australia’s Environment Protection and Biodiversity Conservation Act and on the IUCN Red List, were hit hardest. These large bats, which eat only fruits and nectar, play an important role in pollinating plants and dispersing seeds, helping to regenerate forests.
However, they don’t have sweat glands and struggle to regulate body temperature. When temperatures exceed 42°C, they suffer dehydration, heat stress, organ failure, and death. Desperate, bats descend to lower branches seeking shade, often “clumping” together. “Clumping” is a behavior that can help them moderate heat but traps body heat and accelerates fatalities in extreme conditions.
Populations haven’t had a chance to recover from previous disasters, including the Black Summer that killed an estimated 72,000 flying foxes. Recovery is slow due to the fact that pregnancies last over six months, and it’s typically a single birth.
Death toll
Deaths have occurred nationwide since early January. In Victoria, the government estimated 1,700 deaths at a handful of camps — nearly 5% of the state’s population. At Tatura, more than 700 grey-headed flying foxes died from a camp of about 5,000. At Brimbank park in Melbourne’s North-West, about 100 bats died. In New South Wales, hundreds died across different locations, including a record 500 at one camp near Wollongong, wiping out about a third of that colony.
In South Australia, a Naracoorte colony of roughly 1,000 bats lost more than 80%, leaving only about 180 survivors, including 34 underweight and dehydrated babies needing months of care. Taking care of the injured bats comes at a cost: they need up to about 350g of fruit per bat per day. Judith Bemmer, a carer from Bat Rescue South Australia, told the Guardian that when the heat’s gone, that’s when “the biggest struggle starts for us – the financial struggle.”
According to Professor Justin Welbergen of Western Sydney University, temperatures over 42°C can cause mortality “sometimes at biblical scales.” In dry heat around Melbourne, where peaks reached 42.9°C, spraying colonies with water or using misting machines proved effective at reducing deaths by lowering ambient temperatures and preventing clumping.
However, in humid conditions, such methods can make things worse. Unfortunately, state sources were limited — only three misting machines available for 18 colonies around Melbourne — forcing volunteers to rely on handheld sprayers.
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Rescue efforts
Rescue efforts were commendable but quite challenging. Wildlife Victoria deployed teams to Tatura and Numurkah camps (each holding around 5,000 bats), working with the Department of Energy, Environment and Climate Action and local councils to mist canopies for seven days. CEO Lisa Palma described the work as “incredibly hard” — physically demanding, long days in extreme heat, emotionally tough. She also said it was “immensely rewarding” when bats flew into misted areas, saving hundreds if not thousands of lives.
In Adelaide’s Botanic Park, sprinklers, misting, and park closure limited deaths to a few hundred despite 44.7°C temperatures. Only trained, vaccinated carers in protective gear handled bats due to disease risk (even though cases of infection in Australia are very rare).
Despite all these efforts, many bats died before help arrived, and rehabilitating them remains expensive and long-term. This tragedy is an example of how climate change, by intensifying extreme weather and making deadly heatwaves more common, directly threatens the lives of entire colonies and ultimately, species. Without rapid emission cuts and habitat restoration, flying fox populations are likely to face repeated tragedies.
Editor’s Note: The opinions expressed here by the authors are their own, not those of impakter.com — Cover Photo Credit: Graham Holtshausen
