The study showed that one in 10 or 53 species of Sydney's wildlife was under threat, and that the Royal had the most diverse fauna.

The park also had the largest number of threatened species, its native wildlife being among the most ``regionally significant species recorded in any site''.

Of the 331 vertebrate species documented in the park in the last 10 years, four were considered endangered and 21 vulnerable.

The study ranked Sydney Catchment Management Authority areas in order of importance.

The authority's area, which has around three million people, runs from Stanwell Park in the south, through Campbelltown and Liverpool, to Turimetta Headland in the north.

The State Environment Department used Natural Heritage Trust funding for the survey.

The study, which listed more than 550 native fauna species, was released for Landcare Week, which started on September1.

Landcare Australia's chief executive officer, Brian Scarsbrick, has asked for more volunteers to help conserve Sydney's wildlife. Catchment authority chairman Bob Junor has backed the call.

In Illawong, which was ranked at 32 of most important wildlife sites, the koala is under threat. The survey ranked Towra Point as the second most important wildlife site as it has the largest and most diverse estuarine wetland complex remaining in the authority's area.

The Lower Georges River ranked seventh.

Kurnell, at 8th spot, ``supports a range of threatened and regionally uncommon waders, waterbirds, frogs and other species''. It has the endangered green-and-golden bell frog, and a large number of seasonal grey-headed flying-foxes.

Heathcote National Park was ranked as the 16th most important, wildlife site while Garawarra State Conservation Area came in at 20, Port Hacking 21, Botany Bay National Park 23, Menai 26, and Engadine 43.

More details:

www.landcareonline.

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