It would be a great help to someone like myself (A critic of 'some' aspects of ringing) to have some idea of the normal percentage of bird casualties encountered in the trapping and ringing process, this would, at least, enable some basic evaluation of data gathered, versus casualty rate. As it is, even this is an impossible ask, it would be simple enough for a ringer to record every death or injury, although it would be no more than a guess as to what percent would be prepared to do this. If a bird survives the process then flies off strongly, this is no guarantee that it has not been badly affected, most will seek the nearest cover, then quickly resume normal activities, but not all. Unless a ringer has a video of the mist nets, they cannot be certain there were no predator attacks in their absence, a Mink can bite out a bird leaving nothing but a tiny hole in the netting, it's also possible for a Sparrowhawk to remove a bird leaving no trace of the event, even Water Rail can rob, most usually from the lower part of the net. A ringer using mist nets in the autumn cannot be sure of trapping entire family groups, especially when on migration, in the time it takes to process the trapped individuals, the rest could be miles away, never to be reunited, this could have serious consequences for the survival of those youngsters, I just don't know. I have not even touched on possible, adverse consequences from the use of playback, pulli ringing in some species, constant effort sites and canon netting.