Ecologists say wildfires that have scorched huge swaths of Australia have killed half a billion animals. Nearly a third of the continent’s koalas has been wiped out—and some other species face total extermination as high temperatures and drought fuel the blazes. “Many of the affected animals are likely to have been killed directly by the fires, with others succumbing later due to the depletion of food and shelter resources and predation from introduced feral cats and red foxes,” the team from University of Sydney said.