tx - you only need to tie off the slinky at the top. Use a piece of wire for that - wire will hold up to the weather. The bottom - we've never attached the bottom of the slinky - the more action there is to the slinky, the less likely the squirrels can master it. If you feel that the newer slinkies are too short to do the job, you could attach some sort of weight (maybe some metal washers?) at the bottom of the slinky to stretch it out a bit to over more of the pole.
Here, the red and gray squirrels are much more active and don't seem to be fat. The fox squirrel - bigger and fatter - doesn't move around as quickly or as much.
