Last year I caught about ten rats out of our pond because they were doing damage. I thought I had trapped them out but over the summer they dug a bunch of holes again and the water level dropped several feet. I did some scouting over the weekend and made some sets with no luck. They didn't build a house this year like they did last year so I am wondering if they are even in the pond. Is it possible that they spend the summer in our pond, dug a bunch of tunnels, and then left for the winter? Or do muskrats not do that? I might just be wasting my time with these sets if there are no rats to trap.