Who killed Cock Robin?

I know exactly who. Flad, the cat. I shouted at him and he blinked blankly and dropped the limp bird on the floor. It looked untouched. No marks. Just dead. And now poor Mrs Robin will be sitting on her nest wondering what's happened to her mate and the food. It's heartbreaking.

When I was a kid, our mother trained Cloudy, our huge silver tabby, to kill mice but not birds. He would sit on the lawn with sparrows hopping round him and not make a move. I think it's too late to train Flad, at the age of 12. I wonder what is the biggest threat to birds, cats or lack of a suitable breeding and feeding environment? Probably a combination of both.