An interesting study from the BTO and Natural England suggests that grey squirrels aren't to blame for woodland bird declines. Nice to know, but not a great surprise really given that many (not all of course) woodland species are declining across Europe and there aren't grey squirrels elsewhere in Europe (apart from part of northern Italy).
It would be possible that woodland bird species decline for different reasons in different parts of Europe but that would make life rather tricky.
But whether or not grey squirrels cause problems for woodland birds - and you would have to ask whether red squirrels would have caused more or fewer problems if they were still around - the problem that is firmly laid at the door of the introduced non-native grey squirrel is the demise of our native red squirrel.
Hi Mark interesting that Grey Squirrels innocent of this but they are very destructive and much as I hate to see things culled would in this instance like to see them eradicated and we would soon get the reds back as I see somewhere possibly Anglesey or similar had eradicated the Greys and kept them out and the reds had increased dramatically from small number up to 300 in one year I think(some of this might be wrong but the facts similar)happy for anyone to put it correct.Sad that the Grey are a introduction escapee that went badly wrong.No sly dig there just a sad fact as we had them strip bark off Sycamore trees half way up and of course killed the trees above that.