Use concrete reinforcing wire, wrapped with tight-mesh hardware cloth.
The best way to address this is with a high enough fence to prevent jumping and a "fence" below the ground, preferably of hardware cloth.
When we were done, we covered the outside framework of the tower with hardware cloth, heavy wire mesh with half-inch-square holes.
At minimum most bee keepers wear a brimmed hat and a veil made of hardware cloth similar to window-screen material.
"Heck, they can chew through hardware cloth and chicken wire," he said.
The best procedure would be to spread repellent and seal off the hole with hardware cloth.
Some birdcages are made with galvanized hardware cloth (a type of wire), which can lead to zinc poisoning.
Or larger screens can be fashioned with hardware cloth nailed onto old screen doors or lath and placed over garden carts for major planting-soil improvement efforts.
The hardware cloth can remain indefinitely, but remove other materials in spring or they will provide bark-eating insects safe haven from insectivorous birds.
Think of tiny insects and how simple it is for them to pass through hardware cloth.