Hello Mesocosm, I too have otters visit my pond since it is in a heavily wooded area. In late october with snow on the ground I saw their tracks which are unmistakable with that tail dragging. I decided to try deterrents and would see their tracks in the snow if it didn't work. I put a small battery ultrasonic detector by the pond where they come up from the stream about 70 ft. away, then I put an old radio by the pond with it playing all the time.
So far no new otter tracks in the 5 weeks since setting it up. I'll keep you posted, Good Luck !
