Help! Injured bird rescued from cat what can i do?

[Fizzielove]

So I heard the cat outside making a commotion and went out to investigate, cat had just put her jaws round the poor little bird. I've rescued the bird and set it inside a biscuit tin with the lid off, I'm now sitting outside babysitting the bird so the cat can't get it again. It's alive but not moving, is it just stunned? What do I do with it ? I can't sit here all day!

I came across a cat with a bird it dropped it when it saw me and the bits trotted away before I could catch it. It had an injured wing from the cat and I often wonder what happened to it. If I could have caught it I would have called the rspb for advice.