Having lost 3ybs to dreaded young bird sickness,thankfully there have been no more,for the last 2weeks,I have got a bottle of gerdon 1to use as a preventative,does any one else use it for the same reason
I have 2big plastic owls next to the loft,they seem to be working up til now,you also get cheap wind spinners they change colour as they spin,seems to put them off
I had the same problem a few years ago,I would sit in the loft for hours after dark,and soon as I left it was in killing a yb(chewing the head and neck)so set a tunnel trap on the stone dyke behind the loft and caught the colony alpha rat,never had any problems after that