We've had a bird box up in our garden for the last four years. The blue t*ts checked it out last year but din't use it. This year they nested in it and raised a family. A neighbours kitten did a bit of acrobatics yesterday, hung onto the box, clawed the lid off and made off with the baby birds. I'll obviously re hang it somewhere safer, and secure the lid [It was recommended to be a loose fit drop in - with a block underneath the lid to locate it]. I love cats [though we haven't got one] and yet I could've happily slaughtered it! Anyone any experience of those electronic devices - I think they're ultrasound - that shoo them away. Are they worth buying? I thought if you had a dog then it's scent was enough to keep the neighbouring cats out?