The RSPB among others sell transfers to stick to windows, usually of birds of prey, but have seen cobwebs, some are supposed to be invisble from inside the house you could try these?

Lots of young goldfinches in and around our garden this year due, I suspect from us having nyger seed feeders both in the front and back garden. However they are forever flying into our windows, sometimes they just knock themselves out and manage to fly away after ten minutes or so, but at least three have died. I know birds do fly into windows and it has happened before but never on this scale. I have heard at least ten collisions, and I am not in the house very often in daylight hours. Ours is a through lounge and I suppose the birds see right through it, but apart from keeping the curtains closed I don't know what I can do to help! (Please don't suggest net curtains, my wife wouldn't have them) Has anyone else had the same problem?