Where do we think this immigration is from? Is it the introduced animals in Dumfries and Galloway, is there now supposed to be a continuous distribution down from the Highlands or has the mysterious Pine Marten transporter been at work again?
John
There is a well-established population in Scottish Borders (different from D&G animals) that arose from less clear origins (some, seemingly, were animals released following care in wildlife treatment centres). These have been there for some time and it is one of the study areas for ongoing Pine Marten-squirrel research. This will be the closest established population to Kielder and, I guess, a likely source for this animal.
Highland martens seem to be getting into (through?) Scottish Central Belt Areas but, as far as I understand at present, they have not yet merged into the D&G or Borders populations.
Nick