A new study to assist the revival of one of the UK's rarest mammals is underway in Northumberland.
Pine martens, which were once written off as extinct in England, are becoming more common in Kielder Forest, after being detected on cameras set up to monitor red squirrels four years ago. The agile tree climbers look similar to a ferret or stoat but are significantly larger, with adults growing to more than two foot long and having a bushy tail.
Martens were first spotted in Kielder nearly four years ago, and it's believed to have been the first time they have been in the forest park since tree planting in 1926. And now Forestry England, working with conservationists Johnny Birks and John Martin, have erected 50 pine marten boxes for the first time in England's largest woodland.
