Our second wild brood was 12 strong 1 week ago, as of yesrpterday it was down to 3. This is what happened to the first brood and only one survived. I actually saw them climbing through the new chicken wire when they were small enough so some may have hot lost or into trouble. Our neighbours think that there may be a stoat nearby and that Jackdaws will take chicks when they're small.
Sadly I found a dead one on the wrong side of the chicken wire and as it hadn't been attacked it must've died of exhaustion while trying to get back through.