Hi Heartstones
Ideally, you would cover it back over where it was, but sounds as if that option has passed. But otherwise, what you’ve done sounds a good alternative. Don’t forget to always offer water all day every day, as well, including winter. Also I would give the suet pellets a miss, just cat food should be fine.
It’s a misconception that hogs need to keep warm during hibernation. They actually need to maintain their temperature at a fairly low level. That’s so that their metabolism can slow right down so that they don’t need to eat to keep it running. So insulation is good but no need for extra warming. Having said that, hopefully the compost won’t get that warm at this time of year so will just be added external insulation.
If the hog has already moved, I would continue offering food for a while, just in case. It may move to another nest – our attempts at trying to make a hog hibernating nest isn’t a patch on the amazing constructions they can build themselves! In case the hog is still around, I would leave lots of supplies for more nesting material nearby – i.e. lots of leaves, grasses, etc. If the hog decides to stay, it might want to top up what you’ve put in the box. They use far more to build their nests than we might imagine. A box can be packed full with leaves, etc. with just a small ‘chamber’ for the hog in the middle.
Good luck. I hope all goes well with the hog.