Hi, This might seem like a strange request on a bird forum but I've tried just about everything I can think of to try and find the answer to this.
I built a wooden structure outside my bedroom window for my cat to sit and sun. It's about 2 1/2' X 5' and all enclosed. It tucks under the eaves of the roof and is flush with the outside edge of the eavestroughs. Because I feed birds in my backyard(some 500 feet away, and it wouldn't matter if I stopped feeding them because my neighbour also feeds them at a feeding station some 200 feet away)and the nearest tree is some 50 feet away I thought by just putting up wire on the enclosure it would suffice. I soon realized that it did not and added fine mesh screening on top of the wire. That did not work because sparrows were still getting in. Why they would want to is beyond me. The area must smell of cat. Anyway, I finally added glass all over and caulked with spray foam insulation any small crack where it meets the eavestrough and everywhere else there would be a tiny space or crack. I've gone over and over every inch of the whole thing and still, each year a bird or two manages to find its way in.
Hence my need to find a way to repel birds from this enclosure. I've thought of spraying something on the structure that's used to repel cats and dogs from bushes but it would need to be re-applied often . There's also some plastic-type owls that some people put in their gardens to repel birds from their berry bushes. I don't know if that would work. I'm at a loss for ideas and would appreciate finding the answer. Thanks.