I found this bee on the grass at the CCC Ebury site near Shrewsbury.
Despite this horrific injury, it was still alive - just. I took a couple of photographs then put it out of its misery.
There are 3 causes that I can think of for this injury:
1) Attacked by a bird.
2) Fungus infestation.
3) Some form of parasite.
I favour the first, but would be glad to hear from anyone who can enlighten me.