The Highland Line control zone is a priority area for SSRS, following the Highland Boundary Fault, a geological feature which acts as a natural barrier to invasive non-native grey squirrels, limiting numbers traveling into the red squirrel stronghold of the Highlands and Grampians. 

The Highland Line zone covers significant parts of the Argyll and Bute, Stirling, Perth and Kinross, Angus and Aberdeenshire council areas. SSRS also works closely with the Loch Lomond and the Trossachs National Park Authority.

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SSRS project partners, a network of volunteers and individual landowners are doing their bit to defend the Highland Line, preventing any incursions of grey squirrels to the north and expanding red squirrel territory to the south. 

Grey squirrels outcompete red squirrels for food and habitat, and can replace an entire population of red squirrels within 15 years, unless the grey population is reduced. Some grey squirrels also carry the squirrelpox virus, which doesn’t affect them but is deadly to reds if transmitted. Fortunately, there has never been a case of squirrelpox recorded along the Highland Line, and there has only been one positive case north of the Central Belt.

According to SSRS, the hard work and passion are paying off. Red squirrels are returning to areas where they had previously been completely replaced by grey squirrels. They are are also being reported in higher numbers in some areas, while fewer grey squirrels are being seen in areas where conservation work has been carried out. 

Jen Payne, SSRS Conservation Lead for the Highland Line, said: “It is really encouraging to see red squirrel populations recover and persist along the Highland Line. We know how important this area is for preventing the spread of grey squirrels further north, so our work to defend the line and hopefully expand red squirrel territory further south is vital to protect the red squirrels of the Highlands and the North East. 

“We’re grateful to have so many passionate volunteers, partners and landowners helping us to look after this iconic species. No matter how often you see red squirrels, it’s always a joy to watch them in the wild, so seeing them flourish in new areas, or return to people’s gardens after long absences is heartwarming.”