Skunk holes are 3-5 inches wide. If they were larger, predators could get to them. Do not look for skunks to be in a concrete basement. Stone foundations with dirt crawlspaces are vulnerable. Unless the opening is more than 3 inches off the ground, they will leave a divot at their entry point under structures. Look for one half-circle entrance around the structure’s perimeter and a burrow in the ground. Old groundhog burrows are the largest holes you find skunks using.