MSC,
I think it is the vibration that really bothers the moles. It is also the sound though. Like I said I Am not positive but definate effect on all wildlife and no otters now for years. You can hear them go off when standing close by. I also had a problem with a pair of Muskrats where I got lucky enough to dispatch both on the same day with my 22.They were before the Otters but worried me especcialy burrowing into my dam. no more Muskrats either. We are loaded with all wildlife here. Deer, Bear, Coons and all and the tracks around my pond tell the story. They all avoid it and keep their distance it seems except the occasional coon.
Knock on wood,lol.
