You are certain correct there, the little b*****ds can climb anywhere and were after the nuts for the birds. They had chewed at the containers that the nut were in plus they had made a right mess. This was last year, so I got a humane trap and used to dump them at distance any in the fields but there must have been a family of them and it just continued.
I lost patience and got a battery powered trap for them from Screwfix. Basically and electric chair for mice, in they go after the food and touch the two plates and thats the end of them. Soon got rid of about half a dozen of them and that was that, till recently.
I have disposed of 2 a couple of weeks ago and there is no more evidence for the time being.