Hi Phil. My plan is to use a tilt switch that activates at say maybe a 30 degree angle. This is a huge tube style bird feeder and it takes a squirrel to make it move. I suppose if a crow landed on it, it might shock the crow also, but large birds such as jays, etc. would not be able to make it activate. Neither would wind. My intent is certainly not to kill anything though, I like all wildlife. (I just hate squirrels eating all my birdseed!)
I also meant to originally add that I would gladly pay someone to build this for me if it was a reasonable cost.