My tortoises do their own thing prior to hibernation. Talking about desert tortoises now. They live outside. Their burrow is a man made shelter sitting on cement made from cinder blocks with a plywood top. In the fall I cover the top with sheet plastic to water-proof it, then I start raking up the leaves in their pen and packing the leaves inside the shelter. The tortoise come out and sun or eat, then they go back inside. I keep watching them. When they stop eating I know the time is near. They come out and sun then go back in. Once they stop coming out, usually two or three weeks after they've stopped eating, I make sure the interior cavity is filled with leaves and I block the doorway. Then I continue raking up the leaves but now I pile them on top and around the outside of the shelter. I end up with a great big pile of leaves and inside it is waterproof and insulated enough that the tortoises won't freeze.
The russian tortoises are similar except that I don't leave them outside. Once they've gone to ground and aren't coming out anymore I find them, box them up in shredded newspaper and put them into chest-type freezers. The freezers aren't plugged in and they are situated inside an old abandoned house on my property. The temperature fluctuates inside the house, but the freezers are so well insulated that once the interior temperature equalizes between warm day and cold night, it pretty much stays constant at or around 45F degrees.
I don't disturb my hibernating tortoises. When I hear them scratching around in the spring I bring them back outside. Because they are now acclimated to being cold, I don't worry if the outside temp dip down to cold. I leave the tortoises alone outside. The only time I interfere is if it rains. Being cold and wet is not good for tortoises of any species. So if it rains I make sure they're all inside their shelters and I block the doors.
Thank you Yvonne for taking the time to describe what you do. What you do with your desert tortoises is about the same thing I have been doing with my box turtles. I have a den made from cinder blocks with a wood top. I have two little wooden huts under the big one in case they want to go into those or there is room for them on the outside of the small huts. Then I load it up with leaves. When they are inside for the sleep I put a waterproof tarp over the whole thing. I do leave a small opening for them to come out in case they want to come out for a drink of water. Which one of them did a couple of times last winter. Now with the yearling desert tortoises I'm confused. LOL Why do you put the Russians in the fridge instead of leaving them outside in a man made shelter? ~Michele