The west coast sanctuary is being cleared of feral domestic cats that pose a threat by interbreeding with their endangered cousins. Wildcats are threatened by hybridising with domestic cats, with one study suggesting there could just 35 left in the wild.
The Wildcat Haven, funded by American animal welfare organisations, occupies the Ardnamurchan and Sunart peninsula on the west coast, and has been the site of assiduous work over the last five years to trap, neuter and release feral cats and ensure pet cats are neutered.
The team behind it hope that wildcats may now be able to thrive in the area secure from the further threat of hybridisation.
The project scientific adviser, Dr Paul O'Donoghue, of the University of Chester, said: "Cats of any kind are notoriously difficult to survey. However over the last six months we've really saturated the area with live traps, cameras, vets and ecologists, and had lots of people from the local community out looking as well.
"The only feral cats seen have already been neutered, which means the population should collapse naturally within the next couple of years."
This is thought to be the first time feral cats have been managed in such a large mainland area anywhere in the world.
Camera trap footage, using remote motion-sensor cameras, suggests that Ardnamurchan's wildcats, which could number fewer than 10, might be genetically pure.
The animals will be trapped and DNA tested to establish whether this is the case. If they are, they will be left to thrive and simply monitored, in the hope and expectation that their population will grow. Keeping the cats where they are and protecting them in their own environment is the ideal scenario.
But if the population turns out to be made up of hybrids then discussions will be held with with other agencies about the best way forward. As a last resort, wildcats could be brought to Ardnamurchan from areas of Scotland where Dr O'Donoghue believes they are "doomed", such as the Cairngorms, or from captivity.
Dr O'Donoghue said: "Our goal is to establish populations of genetically-pure wildcats. We are determined not to settle for second best or to settle for a bunch of tabbies that bear a resemblance to wildcats. Protecting anything less than the pure Scottish wildcat will condemn the species to extinction. The behaviour of feral cats and pure wildcats is very different. Scotland's ecology needs the true wildcat and, outside of a wildlife park enclosure, this is the only place in the UK where they are safe from hybridisation."
The area is protected by a heavily monitored buffer zone at a geographic bottleneck which feral cats could not easily migrate past.
Dr O'Donoghue believes this approach is the only way to save the wildcat and would now like to see it expanded on an national scale. "If we had the funding available, we would be very confident of saving the wildcat; the only thing that limits the scale of the Haven project is lack of funding."
Last September, Scottish Natural Heritage (SNH) announced a £2 million, six-year plan to reverse the wildcat's decline, but the effort was criticised by the Scottish Wildcat Association (SWA), which said SNH's broad definition of what constituted a wildcat would lead to the protection of hybridised cats instead of true wildcats. Steve Piper, previously SWA's chairman, who founded the haven project with the SWA in 2008, said it was "the only future the Scottish wildcat has", adding: "This is a huge achievement for everyone involved. Wildcat Haven is easily five years ahead of the SNH action plan and people need to get behind it." He believes it is a good model which could be replicated by SNH elsewhere in Scotland.
A spokesman for SNH said: "We haven't seen this work, but would be really interested in doing so."