One of the two species of rats that live near people is a burrower. Norway rats like to live at ground level or underground, so they commonly dig holes. Roof rats, also called black rats, prefer to nest far above ground, yet will dig holes in the ground when other homes aren't available. Rats harm ornamental plants as well as food plants, so take action to make your garden unattractive to rats.
The Burrow Entrance
Norway rats often burrow along a foundation, under an object, such as a board or cement slab, and in weeds, under shrubs and below wood piles. They also burrow under dog houses and near garbage. Rats come out of their burrows from dusk to midnight to forage. They usually forage withing 50 to 300 feet from their nests, notes Washington Department of Fish and Wildlife. They generally only emerge during the day when there's a large population of rats. Because they use the burrow entrance regularly, the rat hole tends to be smooth and have compacted soil.
The Fresh Burrow
Moist garden soil is one of the rats' preferred burrowing locations. A new burrow may have a fan of soil next to the hole. The dirt displaced by the rat digging is usually up to 1 inch tall. Rats dig holes at night, so you might not see them moving in. To check if a rat hole is in use, put a wad of paper in it. In fair weather, a rat will move the paper out of the way within two days if it's an active burrow.
Rat Hole Structure
The rat digs a hole that's generally 2 to 4 inches wide, less than 18 inches deep and up to 36 inches long. It makes other holes at ground level for emergency exits. A dominant male, his females and their young and low-ranking males share the burrow, which has a nest at the center. Unlike a mole's digging, the rat digs deep enough under ground that there's no raised soil showing at the surface.
Make the Garden Inhospitable
Pet food and bird seed are powerful rat attractants. Store pet food and bird seed in rat-proof containers, such as metal garbage cans with lids. Home improvement and large hardware stores sell these in regular and small sizes. Don't leave pet food, pet water or other standing water out at night. Gather garden produce and fallen fruit promptly. Even animal waste should be disposed of daily, as rats can live on it. Fasten lids on garbage cans with bungee cords. Keep wood piles and boards on raised platforms and clear brush and any junk away from the house.