Britain's dwindling red squirrel population is under threat following a potential outbreak of lethal squirrel pox - which has no cure.
Red squirrels live in a few protected sites in the UK, including Smardale Gill and Wreay Wood in the Lake District and at Formby nature reserve in Merseyside, reports NorthWalesLive.
They can also be seen in Northumberland, Perthshire and the Isle of Wight and Dorset.
Conservatiionists are concerned after a potential fatal case of squirrel pox was spotted by an amateur wildlife photographer a a nature reserve in Cumbria.
The disease is carried by the non-native grey squirrels who are immune to squirrel pox.
However, the red squirrel is not so lucky and is prone to the condition, which is usually fatal within 15 days.
The suspected case was discovered at the Smardale Nature Reserve, near Kirkby Stephen, Cumbria, although it has not been confirmed.
However, it has led to renewed calls for members of the public to be extra vigilant to help conserve the Lake District's most iconic creatures, which was captured by author Beatrix Potter in the enduringly popular The Tale of Squirrel Nutkin.
Cumbria Wildlife Trust has encouraged residents to disinfect squirrel feeders as a precautionary measure.
The dead squirrel was found by Cumbria Wildlife Trust volunteer Matt Staniek, 23, a zoology graduate from Windermere, Cumbria.
"It's a real red alert because it can wipe through a population and completely destroy them", he said.
Bob Cartwright, the deputy chairman of Westmorland Red Squirrels, said if you do get an outbreak "it's heartbreaking."
"It's compounded because so many volunteers like ours and other groups are working so hard to get the reds back and protect the populations."
Attempts are being made to reduce grey squirrel numbers in woodlands around Arnside and Silverdale peninsula to create a buffer zone to prevent it spreading.
Mr Cartwright added: "You couldn't imagine the Lake District without Herdwick sheep or the lakes. It's the same with red squirrels."
The UK Squirrel Accord, a nationwide partnership looking to secure the future of the animal, estimates that there are around 140,000 red squirrels in the UK, where years ago there were several million.
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