One of Australia's most spectacular gorges will be protected against a poisonous cane toad invasion by a knee-high fence, campaigners said Tuesday.

The 1.25 mile cane toad barrier will allow native animals to move freely into Emma Gorge, about 2000 miles north of Perth, while keeping out the toxic toads.

It is the first major tourist attraction in Western Australia to be fenced off and the fence will take three weeks to erect at the mouth of the gorge next month.

Mesh, ropes and pipes erected along the fence help native frogs and animals maneuver over and under while keeping the bigger, more rigid toads at bay.

Studies show more intelligent bush animals will move along the fence and use wildlife gates that are neglected by toads unless they stumble upon them in the first instance.

Stop the Toad Foundation campaign manager Kim Hands said while the fence was not completely fool proof, it had been adapted by volunteers who spent hours watching native animals interact with it.

Cane toads grow up to 10 inches and they threaten native species by taking precious food resources and poisoning animals who feed on them.

"It's time to adapt our strategy to keep toads out of certain defendable areas within Western Australia," Hands said.

"We will be using cane toad proof fences that we have been trialing for the past three years. The results have been very positive -- the fences are the most efficient manual control tool we have to date and have helped us to completely eradicate populations of toads," she added.

The cane toad has spread widely in tropical Australia since being introduced to kill beetles in the 1930s, devouring insects, birds' eggs and native species such as the quoll, a cat-like marsupial.