As already suggested by lollykay, if you know which nest he or she has fallen from, pop on some gloves and put it back. I do this all the time here, (though we've not as many this year because of our cat clan). Baby blackbirds are the worst! But I've put back swallows a fair few times as well - which can be tricky as they nest a lot higher up (they aren't daft and avoid the cats). The nests can get very full particularly the swallows and sometimes they just fall out completely by accident. Not sure what your baby is there though? Good luck.It's the magpies that worry me - they're vicious buggers, and we've a lot round this house. He can flutter a few feet, but not enough to escape anything.