Birds that seem to be pecking on the surface of lawns is normal a sign of a grub called leather jacket which lies beneath the surface of lawns. At this time of year they are commonly now as crane flies or daddy long legs and this is the adult.

wow you must be infected with them

You can get a nematode solution to water on to kill the grubs, or else lay polythene or something over in the evening, lift in the early morning - this brings the grubs to the surface if there are any, and you can either pick them off and kill them or leave them for the birds to eat.

I do not think a blackbird could cause this problem, it could be a fox digging for earth worms although they go much deeper, have you watched the bird doing this? Maybe it could be a small mammal as well, they are hungry in this drought as we have had not enough rain to bring the creatures to the surface. A friend of mine had his lawn wrecked like this by a badger !!

Hi. Did you get a sure answer for your problem. I live in Bournemouth and am having the same problem at the moment.
Did you do aything to clear it? Thanks.
Dave

I think Dave you might have to sit up one night with a lamp shining onto the garden and do a watch!! I suspect this is the work of a badger, good luck.