For decades, NSW town Gunnedah had a booming koala population. So much so that it called itself “the koala capital of the world". But now, the town’s koala population has been deemed “functionally extinct.” National environment and climate editor Nick O’Malley joins Julia Carr-Catzel to explain how the healthiest koala colony collapsed into extinction.Subscribe to The Age & SMH: https://subscribe.smh.com.au/See omnystudio.com/listener for privacy information.