thanks for tip mate i aint using full perspex mate just some section of my roof,alot of pigeon fanciers have this alot of lofts i visit its not full persepx that goes from back to front.All im going to do is certain sections mate so dont think i will have the problems you had with your finches.bellow is an example what im going to do john but on a flat roof.Another difference i reckon is change the colours of exteriors as presently in my widowhood i have two sections i am going to paint one a cool blue and the other a cool green instead of white.So hopefully it makes them relax more