Why do surface mole tunnels follow directly below the electric fenceline
Rumor has it that some moles, such as the star nosed mole, have electroreceptors in their nose.


  In 1993, Gould and colleagues proposed that the star-like proboscis had electroreceptors and that the mole was therefore able to sense the electrical field of its prey[24] prior to mechanical inspection by its appendages. Through behavioral experiments, they demonstrated that moles preferred an artificial worm with the simulated electrical field of a live earthworm to an identical arrangement without the electrical field. 


They may thus be sensing the electrical field of the fence, and interpreting it as a nearby tasty worm.