Concern is growing for Scotland's red squirrel population after a case of deadly squirrel pox was confirmed at Culzean Country Park in Ayrshire.
The virus was found in a grey squirrel, which is unharmed by the pox, but can pass it on to red squirrels.
Until now, cases had largely been confined to the far south of Scotland.
The National Trust for Scotland (NTS) said the presence of the pox virus in Ayrshire "represents a concerning leap to the north".
Squirrel pox was detected at Culzean by NTS rangers and staff from the Red Squirrels in South Scotland Project. It was later confirmed by expert testers.'Worrying development'
NTS nature adviser Lindsay Mackinlay said: "This is a very worrying development as we had until now hoped that the Southern Uplands, together with the active control of greys by many concerned landowners further south, were acting as a barrier and preventing the further spread of this virus north.
"However, we now know that there are some other areas in Ayrshire with 'positive squirrels', near Mauchline and Stair, suggesting the disease has spread south-westwards from there.
"We would appeal for other landowners in the area to work with Red Squirrels in South Scotland Project and attempt to contain the spread. The last thing anyone wants to see is the virus reaching Glasgow."
Mr Mackinlay said further testing would take place at Culzean to see how widespread the virus was.
Once infected, red squirrels suffer a slow, lingering death within about 15 days of contracting the virus.
There is no risk to humans from the disease.
Deirdre Mackinnon, senior ranger at Culzean Country Park, said: "This is a very sad discovery for Culzean. The park had a population of red squirrels until about five years ago, but they have since disappeared totally."