Their numbers are currently monitored and cared for by the Coquetdale Squirrel Group in the face of the growing menace of their grey cousins.
But the group only has a handful of regular supporters carrying out this vital work – and they say there is every sign that they are losing the battle to keep the greys at bay.
It is now calling on Northumberland National Park, the Forestry Commission, Northumberland Wildlife Trust and landowners to prioritise funding for red squirrels.
Ian Glendinning of the Coquetdale Squirrel Group said: “The squirrels I study are on land close by a nature reserve where we haven’t got the resources to tackle the greys.
"So it’s inevitable that the reds catch the disease and their numbers decline.
"The reserve’s owners should either deal with the grey problem themselves or hand over the management to someone who can.”
The group has received some much-needed financial support from private people and firms in the valley, such as the Tarmac Group which runs the Harden Quarry, as well as bodies like the Henfrey Charitable Trust.
Members of the public who spot grey or red squirrels can report their sightings online at https://experience.arcgis.com/experience/6ffe8f631dec4330ae7e0664f2092626/
There will be a public meeting to address the issue on Wednesday, May 11 at 7.30pm at the Rose and Thistle pub in Alwinton when it is hoped the organisations involved plus local landowners and the public will attend.