Well, let's have a think. Our cat does half a dozen birds or so a year.. (that we know of, though she's usually most keen to share) Assuming 7 million cats in the uk, assuming some will be stone killers and some namby-pamby wuss-cats; assuming they hit their bird-killing, beak-twisting stride when they're still youngish and then lose their touch.. I'm gonna have a stab and say more like 50,000 birds. 50k Dead birds.