THE Scottish wildcat, the country's most endangered mammal, may have disappeared from one of its favourite habitats, prompting fresh fears about its survival.
The renowned wildlife film-maker Fergus Beeley, who captured the first film of the animals in Scotland, followed the exploits of a mother and her kittens at a den in the Black Isle in 1994.
The site was one of the few confirmed Scots habitats of the highly elusive wildcat, which could become extinct within ten years, with just about 400 remaining.
But returning this year to the same spot, he found no evidence of a den still in existence. His findings can be seen tomorrow in a BBC programme on the threatened species.
It comes as Scottish Natural Heritage (SNH) prepares to launch a survey in an effort to establish the size of the wildcat population and its distribution.
Mr Beeley told The Scotsman: "I looked at the very places where we put the camera all these years ago. The only conclusion that I could make was that the den where we filmed was no longer active.
"There was no evidence at all of wildcat. But they have large territories and it is possible that they had found a new denning area which I was not familiar with."
He said one possible reason for the disappearance was a lack of rabbits in the area.
He added: "It's definitely a threatened species and what comes to light is the fact that they are so elusive it's difficult to get the data. Sightings are very rare and therefore it's difficult to make assumptions on what the population is doing.
"The fact it is so elusive is one of the greatest threats to its survival."
Ro Scott, a policy and advice officer concerning mammals at SNH, said little data is currently held on the wildcat, which is a priority species for conservation, with the last major survey now about 20 years old.
She said: "I live in the Black Isle and I am a local mammal recorder and there have been no wildcat recordings for a few years now.
"But they may not use all their dens all the time, they may use one a particular year and then move off to another one other year. It may not mean there are no wildcats in the area at all. They are incredibly difficult to see, even when we know they are there."
Ms Scott went on: "But in any kind of area semi-isolated like the Black Isle, there is more likelihood for a population to go extinct at a local level when they are not connected to the bulk of the rest of the population. So that is a possibility."
She agreed that the lack of rabbits might be a factor.
She said: "Like any carnivore they are very dependent on the level of prey. They feed on rabbits, but also on voles, mice and birds so it's quite difficult to attribute the desertion of a particular den to any particular item of prey, although it might be a contributory factor."
Steve Piper, a wildlife film-maker and a trustee of the Scottish Wildcat Association, said research has suggested that many of the Black Isle wildcats were hybrids. He said: "Breeding with domestic cats is the key thing affecting their long-term conservation and it ties in with what people are seeing across the country.
"About 90 per cent of wildcats seen here are effectively just angry domestic tabbies, and that is the pattern we are seeing in Scotland and across Europe, as well as Africa and Asia.
"All the research is bringing back the same sad news that the cats are slowly disappearing."
• Saving Planet Earth is being shown on BBC Scotland tomorrow at 7:30pm.
• THE Scottish wildcat is Britain's last large mammal predator.
It is about 50 per cent larger than the average domestic cat, with males typically weighing 6-8kg.
Because of its elusive nature, very little information exists about the size of the population, but it is thought there are now fewer than 400 and it is feared the species could be extinct within a decade. It is largely nocturnal, resting in a den or in dense forests by day and patrolling and hunting up to 10km by night.
Footage captured by Fergus Beeley, the film-maker, of a wildcat in Ardnamurchan showed a mother making a round trip of 14km to find food for her young.
Wildcats can mate with domestic cats, leading some scientists to believe modern wildcats are essentially extinct and what remains is all hybrid.