I'm surprised too. Four wheelers get stolen like crazy around here, ATV's too. Never heard of a tractor being stolen though.
My property is pretty isolated and is right next to my B-I-l's ranch. The road we're on is about 6 miles long. We're right in the middle of it. On this road there is a small farmhouse at one end, his large farmhouse, a small shack next to his barn and another run down shanty at the far end. My cabin and one other cabin are off the road considerably, and both are weekend places. There has never been a robbery until last year when someone took all of his saddles out of his tack room at the barn (8 of them), a portable air compressor, a spray washer and a 4 wheeler on a trailer that belonged to someone else. Up until this, they had never locked the doors to the house or barn, never took the keys out of their cars.
My cabin is about a mile from his house and down in the woods. Most everything in it is hand-me-down and yard sale type stuff except for a newish microwave. So nothing much to steal. My shiny new tractor (still seems new to me after 15 months) just sits there with a tarp over it. I always put the key in the cabin, which apparently is meaningless since they could use any old key or hot wire it pretty easily. I leave it in gear and leave the PTO in the on position with the hopes of foiling the casual thief or potential joyrider/vandal. I don't really think anyone could drive it away since it is such a long drive to anywhere, but someone who knew about the tractor and how 'unguarded' it is could easily knock the gait down and go in there with a trailer or rollback and drive off. No one would ever see them. Not much I can do about it I guess. Homeowners covers theft and vandalism.