Any ideas what might be doing this? Until about 9 months ago I'd never seen it and then all of a sudden almost every dead standing tree seems to have been attacked. It tends to happen mostly from about knee to shoulder height but I've also seen it much further up the trees and so suspect it is a bird that is doing it. We also have red squirrels but they have been around for years and I haven't seen this until recently, unless it is a new hobby with them. It looks to me like what ever is doing it is trying to get at insects in the dead wood. I've no experience with woodpeckers and the photo was taken in Ireland where woodpeckers are extremely rare, in fact it is only recently a friend was telling me that there are woodpeckers in Ireland as I've never seen one and wasn't at all sure there were any here.