Camera traps have recorded rare pine martens in Northumberland’s Kielder forest for the first time since it was planted in 1926.
The cameras are set up in a remote area of Kielder Water and Forest Park as part of a red squirrel monitoring project, but among other wildlife caught on the footage the “unexpected visitor” was recorded for the first time.
Clearance of woodlands and persecution had a severe effect on pine marten populations, leaving it confined to a few of the more remote areas across Britain and Ireland by the early 20th century.
Their stronghold is now in Scotland, and conservationists welcomed the evidence that pine martens are beginning to re-establish themselves in northern England.
Their return could also be good news for the red squirrel in Kielder, as research from Scotland suggests that where pine marten numbers rise, red squirrel numbers also increase but populations of their competitor the grey squirrel fall.
The camera images were first seen by John Hartshorne, who manages fieldwork and ecology education organisation Albion Outdoors and helps with red squirrel surveys as part of the Red Squirrels United project.
He said: “It is very common to see wildlife other than squirrels on the cameras I use. Badgers, foxes, deer and birds of all sorts are regular visitors.
“This July I have caught some excellent pictures of red squirrels but also an unexpected visitor – a pine marten, sitting on top of one of the squirrel feeders.
“This was most unexpected but I now have both still pictures and a short piece of video firmly placing pine marten in Kielder Water and Forest Park.
“Historically, pine martens were commonplace but habitat clearance and persecution has led to them being eliminated from nearly all of England.”
A number of organisations are working together to help pine martens in northern England, including Forestry Commission England, Northumberland Wildlife Trust, Aberdeen University and Vincent Wildlife Trust.
Tom Dearnley, a Forestry Commission ecologist, said: “As the forest nears 100 years in age, it is increasingly being colonised by rare and protected species.
“Pine marten returning to England, over the Scottish border, have been anticipated for some time, encouraged by the efforts we are making to create ecologically diverse forests.
“We are delighted to see photographic evidence of their return, in a forest valued by so many people.”
Conservationists said pine martens are natural predators which could help manage grey squirrels, an invasive species introduced in the 19th century which compete with native red squirrels and spread disease to them.
Simon O’Hare, of Northumberland Wildlife Trust, said: “It is well documented that grey squirrels out-compete red squirrels for food and also pass on a deadly virus, squirrel pox, to reds: this is one of the main reasons that the species in under threat.
“The natural return of pine martens in areas of northern England is an exciting prospect, as it could have a knock-on effect by suppressing grey numbers, allowing native red squirrels to prosper once again in our woodlands.”