Winter is the time we carry out work on our bird boxes. Every box is inspected. If it is broken it is either repaired or replaced, depending on its condition. Old nesting material is removed and the box is disinfected using a special liquid which is safe for the birds but kills off the bugs. Once the box is spick and span for its new tenants it has a number marked on it and it is photographed with a GPS camera. We know the position of all our boxes and are able to find them easily using this system.
If you would like to make a box and put it up in your own garden you can find all you need to know on the RSPB web site
or the British Trust for Ornithology site ;- https://www.bto.org/about-birds/nnbw/make-a-nest-box