Nightmare Craigy! its funny with all these birds how somtimes you can sense somthing not quite right. I had a problem with a young Goshawk in the nest this year, I put it back with its parents at 4 days and went in at 9 days to ring them, two days later I heard one twittering in the nest but somtimes you can put this down to one being a bit cold, anyway! I thought I better go in the aviary and check! it turns out the chick had a small twig from the nest lodged under its ring, unfortunatly the bird had twisted round and round breaking its leg .
to cut a long story short it was a clean break