My dad made a similar mousetrap for the outhouse at our hunting camp. A five gallon bucket with a coat hanger wire across the top with a tin can that would spin on the wire. Put some peanut butter on the tin can, several inches of water in the bucket, set it next to your wood pile with a gang plank leading over to the edge of the bucket. I'm sure you can find a diagram of this on the net. I'm surprised that you can't take the city busses for security purposes. That puts a whole new light on the situation. The good news are the plums. I never saw plums, but I always figured some varieties would grow in the Highlands along with the apples, peaches, and other temperate climate fruits.