His winning work, and those of the other 32 winners and highly commended finalists, are on show at the National Archives of Australia from today.

McWilliams, a former art teacher who now paints and runs an antique shop, won this year for his painting Bandicoot Playground. He first won the prize in 2005 for Centre of Attention, which depicted the thylacine.

In Bandicoot Playground he has painted the eastern barred bandicoot.

''They're relatively common in Tasmania, not so common here in mainland Australia, I think mainly because of the fox and the dingo,'' he said.

''I like them as animals ... the shape, the unusual nose.''

He said he would probably put use some of the prizemoney on renovating his house.

The section winners were: in sculpture, Paul Ballantine (South Australia) for Survival Down to the Wire, a koala made of recycled chicken wire; in painting, Sara Shamma (Syria) for Rhinoceros; and in works on paper, Scott Marr (NSW) for We Eat What We Are.

The People's Choice Award went to Janine Mackintosh's Dreaming of Water Murray Mandala, made of eucalyptus leaves.

Canberra artist Brenda Runnegar's oil painting Spotted Fish was highly commended and is in the exhibition.

This year was the first time Runnegar had entered for the prize.

''I've started doing a whole series of what I call fish portraits. I'm having an exhibition of the others at ANCA [Australian National Capital Artists' gallery] next month. This was one of the very early ones.''

Runnegar said she was trying to raise people's awareness ''of the wonderful things under the ocean''.

The Waterhouse prize offered by the South Australian Museum and commemorating its first curator, naturalist Frederick George Waterhouse, is Australia's richest natural history art prize, with total prizemoney of $107,500, including $50,000 for the overall winner.

This year it attracted a record 693 entries this year, with 102 of those selected as finalists. The exhibition of winners and finalists has been coming to the National Archives since 2005, except for 2006 when, owing to a prior exhibition booking, it was shown at the High Court of Australia.

The exhibition is on at the National Archives until November16.