Scotland's red squirrel population could be extinct by the end of the century, unless urgent action is taken, a conference has heard.
Delegates are discussing how to protect red squirrels from the greys
A total of 130 squirrel experts took part in the Edinburgh conference which looked at ways of tackling the threat to red squirrels.
They were given three months to come up with a plan to save the species in Scotland.
There is particular concern about the threat from deadly Squirrel Pox.
The disease has not yet been found in Scotland's red squirrels but five grey squirrels in the south of Scotland were recently found to be carrying the virus.
Scotland is currently home to 75% of the UK's red squirrel population, but their habitat is gradually being taken over by the grey species, which was introduced to Britain from North America in the 19th century.
Speaking to BBC Scotland's news website before the conference, Deputy Environment Minister Rhona Brankin said: "We must act now to save our native red squirrel population.
"After visiting red squirrel strongholds in Scotland it became clear to me that we have potentially got a major problem unless we do more."
Scottish Natural Heritage has come up with a list of 127 priority woodlands where it wants to protect the red squirrel from the greys.
It plans to publish its action plan to save Scotland's 120,000 remaining red squirrels at the end of May.
There is concern that Squirrel Pox will hit Scotland's red squirrels
The Scottish Executive has set up a squirrel survey and has urged the public to report sightings of both red and grey squirrels.
"We want to make sure we have the most accurate and up-to-date information," she said.
"This shows there is now clearly a threat in Scotland," Ms Brankin said. "We have to listen to the best scientific advice and get serious about this.
"We need to look at the ways grey squirrels come into the country. They like broad-leaf trees so are likely to follow river valleys.
"We have to think of ways to discourage greys while encouraging reds."
She added that there were no plans for a mass cull of grey squirrels in Scotland. A cull was recently announced in England.
She said research was currently being carried out into ways of controlling the grey squirrels, including a contraceptive pill.
Ms Brankin also revealed that she had asked SNH to draw up a species framework to discover which Scottish species are under threat.
"We have a huge responsibility to take care of our native species," she said.