The department now was trying to save another six species struggling to survive.

Imported predators such as foxes and cats, and loss of habitat due to land clearing were said to be the main reasons for the demise in wildlife numbers.

"It is not good to see any species disappear from an area but it should be said that the Illawarra is still an area rich in diversity in terms of environment and wildlife," said ecologist Kylie Madden who helped to write the report.

The species the department listed as "extinct" - animals which could no longer be found in a given area - were: eastern quoll, ground parrot, wompoo fruit dove, superb fruit dove, rose-crowned fruit dove, bush stone curlew, jabiru, and the magpie goose.

Those listed as high conservation priority were: stuttering frog, long-nosed potoroo, regent honeyeater, swift parrot, eastern bristlebird and green and golden bell frog.

In some cases these birds, mammals and amphibians, once scattered throughout the Illawarra, were down to one or two colonies.

The department's manager of biodiversity, Tom Celebrezzi, said there were several Illawarra and national restoration programs underway to revive dwindling populations of endangered species.

"We are also carrying out studies to try to identify factors which might help reduce their decline," he said.

Members of the community could help in various ways, including keeping cats in at night and not dumping any garden waste near bushland.

"Dumping garden waste allows weeds to spread which interferes with natural habitats," Mr Celebrezzi said.

He also advised against taking rock from the bush to use in gardens as this disturbed snake habitats.