In a stretch of remote bushland in the Australian outback, rangers have begun clearing a historic line in the red sand.
It is a line that could eventually mark the difference between life and extinction for a range of endangered native animals.
This line in the centre of the continent marks the boundaries of an ambitious project to build a fenced sanctuary - labelled a modern-day version of Noah's ark - to protect native species from predators, especially feral cats, the worst of Australia's non-native predators.
The sanctuary is envisioned to cover about 80,000ha and will be the world's largest feral-free enclosure. It is being built in Newhaven, about 350km from the city of Alice Springs, by conservationists from Australian Wildlife Conservancy, a non-profit organisation.
The chief executive of the organisation, Mr Atticus Fleming, said the fence would "turn back time" and restore the region to conditions before the arrival of British settlers in the late 1700s.
"The middle of Australia is the global epicentre for mammal extinctions," he told The Straits Times. "Unless we take really dramatic steps - like establishing the largest cat-free environment on the planet - Australia will lose more species.
"We have this natural capital that is unique in the world and we are letting it slip away."
>$10.8m Total cost of the sanctuary, which will be the world's largest feral cat-free enclosure.
150,000 The total population of animals expected by the time the fence is completed.
Australia has long been known for its unique animals such as koalas and kangaroos but has also been developing a dubious reputation for its tragic loss of native species.
Since the arrival of British settlers in 1788, many native animals have become extinct or endangered, due mainly to predators, such as wild cats and foxes, brought over by early settlers.
Australia has lost about 30 native mammals - more than any other country in the world - and 108 are listed as endangered. These extinctions amount to about 35 per cent of the world's modern mammal extinctions. It is believed that 28 of the extinctions involved feral cats, including 22 directly caused by cats.
The Newhaven sanctuary will seek to restore local populations of 10 endangered mammals which will be brought in from places where they have survived.
The species include the numbat, a small bushy-tailed anteater, of which fewer than 1,000 are believed to still survive.
The other creatures are the bilby, a large-eared silver creature known as Australia's Easter Bunny; the mala, a rabbit-sized wallaby also known as a rufous- hare wallaby; the western quoll; red-tailed phascogale; golden bandicoot; burrowing bettong; brush-tailed bettong; shark bay mouse; and central rock-rat.
In the absence of feral cats, it is believed that the animals will thrive. Australian Wildlife Conservancy chief executive Atticus Fleming said the species inside the sanctuary are expected to "breed like rabbits".
There are an estimated six million feral cats across 99.8 per cent of Australia, though some estimates say there could be up to 11 million.
Each cat kills between five and seven native animals each night, a tally which has had a severe impact on creatures such as small kangaroos, bandicoots and native rodents, based on studies by scientists and conservation groups.
The first stage of the sanctuary project began last month and is due to be completed early next year. It involves building a 45km fence enclosing 9,450ha of land.
At least 10 species will be placed in the sanctuary over the next four years. The fence will be electrified and will aim to keep out feral cats.
It will allow 10 mammals - such as the numbat and the bilby - to be reintroduced. The creatures will roam wild but surveys will be conducted to monitor their population.
The second and final stage, which will see the sanctuary expanded by 70,000ha, will take about five years and is expected to cost about A$5 million to A$8 million (S$5.4 million to S$8.7 million), on top of the A$5 million for the first stage, of which A$750,000 will be paid by the federal government. Construction is due to start in 2020.
The total population of animals is expected to number about 150,000 by the time the fence is completed.
SAFARI DOWN UNDER?
Eventually, it is hoped, the sanctuary will provide a glimpse of pre-settlement wildlife and will become a destination for visitors from Australia and around the world.
Any plans for tours or local accommodation will be made in cooperation with the indigenous Warlpiri, the traditional owners of the land.
"You will have a landscape that is again full of animals," Mr Fleming said. "At that point it will be an important destination for anyone who wants to see the Australian landscape as it once was."
Australia has long used fences to protect animals from predators, though they have typically been built to prevent deaths of farm animals. The longest is a "dingo fence", built in 1885 to protect sheep and cattle from native dogs, that measures more than 5,400km.
Other countries, including New Zealand, have built small sanctuaries. But, globally, there has never been such a large undertaking aimed at conservation.
'AN ARK OF SAFETY'
The fence at Newhaven will be 180km long and involve more than 1,600km of wire, 35,000 pickets, 500km of netting and some 12 million clips to hold the netting in place.
An overhang at the top of the fence will prevent animals from climbing over while netting at the bottom will prevent burrowing. It will aim to keep out foxes and rabbits as well as cats.
Australia's Threatened Species Commissioner, Mr Gregory Andrews, said the sanctuary at Newhaven is the largest and most significant such project in the world.
"It is like an ark - a Noah's ark," he told The Straits Times.
"For species that are driven to the brink, that can't cope with feral cats, this will be an ark of safety. The beauty of this is that it is so big that the species inside will be operating like wild species in the open," he said.
In 2015, the federal government adopted a threatened species strategy which set a five-year plan for preventing further extinctions. This included establishing 10 new large fenced-off, feral-free areas on the mainland, clearing five islands of cats and culling two million of the creatures by 2020.
Mr Andrews also said the sanctuary is vital because Australia is the only continent - aside from Antarctica - which evolved without predatory feral cats. As a result, he added, "our species did not evolve to cope with the cats".
The cats are difficult to spot, though their tracks are evident in the dirt. They resemble ordinary pets but are largely nocturnal.
Besides the fenced sanctuaries, the government has also begun a mass cull of cats, mainly via shooting and trapping. Aboriginal trackers have been helping to hunt the cats and remove them from the area that will form the sanctuary.
Mr Andrews said technology in the next 20 years could offer new solutions to help staunch species loss. "When we lose our animals and plants, we lose part of what it is to be Australian," he said.