Rats are common rodents in both urban and rural areas, often found near human activity. Many rat species are proficient burrowers, creating extensive underground tunnel systems.
The Burrowing Behavior of Rats
Norway rats (Rattus norvegicus) are known for their digging abilities. They construct burrows in various soil types, preferring softer earth at least a foot deep. Their powerful teeth and dexterous paws allow them to excavate tunnels quickly.
A rat burrow features a main entrance and often one or more less obvious exit holes, sometimes called “bolt holes,” which serve as emergency escape routes. Inside, these burrows form a network of tunnels and chambers. Most burrows are 12 to 18 inches deep and can extend up to 3 feet in length. Near a building’s foundation, burrows might reach depths of up to 4 feet to access beneath the structure.
Purposes of Rat Burrows
Rats construct burrows for a variety of reasons for their survival. Burrows primarily serve as secure shelters, offering protection from predators such as cats, dogs, and birds of prey, as well as adverse weather conditions like cold, heat, and rain.
Beyond immediate protection, burrows are also sites for nesting and breeding. Female rats utilize these secluded spaces to give birth and raise their young. Additionally, rats use their burrows for food storage, caching supplies in secure locations within their tunnel networks. The intricate system of tunnels also provides discreet travel routes, allowing rats to move between their nesting sites and food sources while remaining hidden from view. These networks also function as quick escape routes when rats sense danger.
Recognizing Rat Burrows
Identifying rat burrows involves specific signs and typical locations. The main entrance holes are usually round or slightly oval, measuring approximately 2 to 4 inches in diameter. These openings often appear smooth and well-worn from frequent use, with loose dirt sometimes fanned out around the entrance, particularly with newly dug burrows.
Beyond the burrow openings, other indicators of rat activity include compacted paths or “runways” in grass or dirt, which rats create by repeatedly traveling the same routes between their burrows and food sources. These runways are often found along walls, fences, or other vertical surfaces, as rats prefer to move along established paths. Dark, greasy rub marks may also be visible along these pathways or near burrow entrances, resulting from the oils and dirt on a rat’s fur. Additionally, the presence of rat droppings—shiny, black, capsule-shaped pellets about 1/2 to 3/4 inches long—or gnaw marks on nearby objects confirm an active infestation. Common locations for burrows include:
- Areas near building foundations
- Under sheds
- Decks
- Woodpiles
- Dense vegetation
- Along riverbanks and compost piles