The cameras are in a remote area of the beauty spot, installed as part of a red squirrel monitoring project.
The images were first seen by John Hartshorne, who manages the fieldwork and ecology education organisation, Albion Outdoors, and has been helping with the squirrel surveys as part of the Red Squirrels United project for several years now.
The news is encouraging for the partnership of organisations working together for pine marten conservation in northern England, including Forestry Commission England, Northumberland Wildlife Trust, Aberdeen University and Vincent Wildlife Trust.
John said: “It is very common to see wildlife other than squirrels on the cameras I use, but seeing a pine marten, sitting on top of one of the squirrel feeders, was most unexpected.”
Historically, pine martens were commonplace but habitat clearance and persecution has led to them being eliminated from nearly all of England.
Ongoing studies in collaboration with the University of Aberdeen will provide evidence on how pine marten influence other species in Kielder Water and Forest Park.
Recent research carried out by Aberdeen University found that in Scotland, areas where pine martens were increasing, red squirrels also increased, but grey squirrel numbers plummeted.