Many Australians were forced to decide whether to stay in their homes or evacuate because of the fires. For Wilson and Willis, their wildlife-care work was the priority.
"We had way too many animals in the house and around the house so we really couldn't go ... we decided we were going to stay and fight," Wilson told Reuters.
Wildlife Information, Rescue, and Education Service Inc. (WIRES) — Australia's largest wildlife rescue organization — reported that volunteers helped with over 3,300 rescues for sick, injured, and orphaned wildlife.
Large animals are sometimes able to escape wildfires, but smaller animals often cannot run far or quickly enough, or hide safely from fierce and quick-moving blazes.
Willis told Reuters that she had never seen such powerful fires, and that most animals — such as possums, gliders, echidnas, lizards, and even many birds — were not quick enough to escape.
Kangaroos' natural habitat in Australia is the open bush. But as humans have cleared brush for agriculture and development, kangaroos and humans have been forced closer together.
Climate change has increased the frequency and severity of fires. This was one of Australia's worst wildfire seasons ever.
The isolation of Australia's ecosystems means many species are unique to the country. Experts fear that up to 1 billion animals might have perished in the fires, including some from threatened and endangered species.
Kangaroos are not endangered — they're designated at the level of "least concern" by the International Union for Conservation of Nature because their population is abundant.
In January, a fire ravaged a third of Kangaroo Island, which sits off the coast of South Australia and is home to lots of unique wildlife. Thousands of kangaroos and koalas were thought to be killed.
"This is a national tragedy and a threat to our Australian way of life, in both urban and especially regional communities," Dermot O'Gorman, CEO of the Australian chapter of the World Wildlife Fund, said in a statement in November 2019.
Scientists expect fire-prone areas around the world to see prolonged fire seasons and more severe wildfires as climate change continues to worsen.