It has been a weird few weeks of weather. In North America, Canadians and Floridians alike shivered through freezing temperatures, bomb cyclones and a polar vortex. (It got so cold that iguanas froze and fell out of trees.)

Over in Australia, meanwhile, it has been hot. Sweltering, really.

In Sydney, temperatures swelled to 117 degrees Fahrenheit on Sunday, the hottest it has been since 1939.

Posted by Help Save the Wildlife and Bushlands in Campbelltown on Sunday, 7 January 2018

That oppressive heat, a side effect of climate change, has made life hard for the country’s humans. Heat waves result in 10 percent more calls for ambulances and 10 percent more deaths, local experts said.

For some animals, it has been nearly unbearable. “Anytime we have any type of heat event, we know we’re going to have a lot of animals in need,” animal specialist Kristie Harris told the BBC. It was so hot that possums burned their paws on roofs and roads. Koalas around the region were being sprayed down to keep them cool.

And at least 500 flying fox bats died because of the heat.

Animal rescuers in Sydney described “heartbreaking” scenes of dozens of dead baby bats piled on the ground. “It was unbelievable. I saw a lot of dead bats on the ground and others were close to the ground and dying,” volunteer Cate Ryan told the Guardian. “I have never seen anything like it before.”

The species’ pups are particularly vulnerable, she said. “They have less heat tolerance,” Ryan said. “Their brain just fries, and they become incoherent.” Often, she said, they will simply get too hot and fall to the ground while the adults seek out precious shade.

The flying fox is the most populous bat species in Australia, though conservation groups say it is vulnerable to extinction. The bats live in woods and swamps along Australia’s east coast. They play an important role in pollination and seed transportation.

More than 500 flying foxes have died of heat stress, according to the New South Wales Wildlife Information, Rescue and Education Service. At least 120 flying fox pups were brought in for hydration before being returned to their mothers. “Just like human babies, they’re really vulnerable when they’re young,” Harris told the BBC.

Researchers warn that warming temperatures will only make bats more vulnerable. In 2008, an article in the Proceedings of the Royal Society B: Biological Sciences found that climate change was contributing to species decline.

“Temperature extremes are important additional threats to Australian flying-foxes and the ecosystem services they provide, and we recommend close monitoring of colonies where temperatures exceeding” 42 degrees Celsius (108 degrees Fahrenheit) are predicted, they wrote.