I had a search but didn't find this question before - sorry if I missed it

I am new to allotmenting and have been told that what is munching away on my lovely brassicas (Brussell sprouts and calabrese) is pigeons
I am on a really tight budget and just can't afford to get netting just yet, I have tried old CDs strung from string between two canes, but I think the pigeons ust see it as some form of fancy lighting like the good old disco ball we used to bop around under!
Do any of you have any ideas that could save my poor brassicas until I manage to get some netting please?