The project was aiming to re-establish a koala population in an area of south-eastern NSW where the species is locally extinct. The spokesperson said the remaining six koalas were healthy and returned to their original habitat in the Upper Nepean. “This koala translocation experiment has been a catastrophic failure and raises serious questions about how it happened,” she said. The first relocated koalas from the Upper Nepean State Conservation Area to a predator-free fenced area in Yiraaldiya National Park in western Sydney. The department said three of the koalas had since died, with likely causes being tree fall or predation.