Question Author
Today is bright and sunny so I spent some time preparing the area and spreading the cat crystals. I will report on progress in due course. A friend who has tried the sonic deterrent says his neighbours cat sat sunning itself in front of the device, but another regularly visiting cat has not been seen since the device was installed. Perhaps, like humans, cats hearing varies and I am sure there could be deaf cats. I used my sonic deterrent for a year before I had any complaint and it has been suggested that the frequency can vary as the unit gets older. Perhaps someone knows who something about ultra sonic frequencies can give us the explanation. I am puzzled by the salmon juice suggestion, I thought cats liked fish. Perhaps the tin has an effect on the taste of the juice.