Dead leaf??

Finished work early today and on teh way home was wondering what to blip today. As I parked in the drive I noticed what looked rather like a bird-shaped brown leaf on the grass in among the daisies and clover. On getting a bit closer I realised it actually was a bird - a baby sparrow who sat and let me get quite close.
I kept an eye on it after coming in as I didn't want a cat to get it, but when I went out for another pic when the sun came out it flew into a bush.
I wondered if it had flown into the window and stunned itself - something left a mark recently (though as I can't remember when the window was last cleaned it might not have been that recent!).
Going to the Lake District for a week so no posts for a while.