One tried and true way is to have your squirrel make contact with the uninsulated top wire connection.
A second is to have an osprey place his recently caught fish at the same location.
Snakes have been known to do it but they are much harder to train
“Snakes have been known to do it but they are much harder to train”
They’ve trained a snake to open doors, the Reptile Commandos can’t be far behind:
http://www.youtube.com/watch?v=Bxc_55ur-J4
Ping for a snake-training opportunity.