Platypuses have been relocated to the Royal National Park in Sydney, after they disappeared from the park's waterways about 50 years ago.
The iconic Australian animal is believed to have disappeared from the national park after a major chemical spill on the Princes Highway in the 1970s, but numbers may already have been in decline.
A joint project by the University of New South Wales, NSW National Parks and Wildlife Service and the World Wildlife Fund has reintroduced five females to the Hacking River, with a group of males to follow next week.
