Rats are cautious, nocturnal animals. By the time you actually see one, there is usually already a well-established population hiding somewhere in your property. The good news is that rats are not as discreet as they think. They leave behind a trail of evidence that, once you know what to look for, is hard to miss.

1. Droppings

Rat droppings are one of the most reliable indicators of an active infestation. Brown rat droppings are dark brown, roughly the size and shape of a large grain of rice, and tapered at one or both ends. You will typically find them concentrated along walls, behind appliances, under floorboards, and in roof spaces. A single rat can produce up to 40 droppings per night, so even a small infestation leaves a significant trail quickly.

Fresh droppings are dark and moist. Older droppings dry out and become grey and crumbly. If you find both fresh and old droppings together, the infestation is ongoing.

2. Gnaw marks

Rats have teeth that never stop growing, so they gnaw constantly to keep them in check. Look for chew marks on wooden joists, skirting boards, door frames, food packaging, and electrical cables. Gnawed cables are a serious fire risk and one of the most dangerous consequences of an untreated rat problem.

Fresh gnaw marks are pale and rough-edged. Older marks darken over time. If you find pale, fresh-looking gnaw marks, rats are still active in that area.

3. Runways and smear marks

Rats are creatures of habit. They follow the same routes repeatedly, typically running close to walls and through gaps in structures. Over time, the grease and dirt from their fur leaves dark smear marks along these runways. You may also notice worn, greasy tracks along the base of walls or across beams in loft spaces.

These runways are useful for placing traps and bait stations, as rats are far more likely to interact with control measures placed directly on their established routes.

4. Scratching and scurrying sounds

Rats are most active at night. If you hear scratching, scurrying, or gnawing sounds coming from inside walls, under floorboards, or in the loft after dark, rats are a likely cause. The sounds are often described as a rapid, light scratching, quite different from the slower, heavier movement of a larger animal.

In commercial premises, staff sometimes report hearing movement in ceiling voids or behind kitchen units during quiet periods. Do not dismiss these reports.

5. Nests and burrows

Rats build nests from shredded material: insulation, paper, cardboard, fabric, and plant matter. Nests are typically found in hidden, undisturbed areas such as loft insulation, cavity walls, under decking, and in compost heaps. In gardens, look for burrows in banks, under sheds, and along fence lines. A burrow entrance is typically around 70mm in diameter, smooth-edged from regular use, and often has a small pile of freshly excavated soil nearby.

What to do if you spot the signs

Rat populations grow quickly. A pair of rats can produce hundreds of offspring in a year under the right conditions. Early intervention is always more straightforward and less costly than dealing with an established infestation.

Over-the-counter products can provide temporary relief but rarely address the root cause. A professional technician will carry out a thorough survey, identify entry points, place bait stations in the correct locations, and advise on proofing measures to prevent re-entry.

Pest King provides rodent control across Aberdeen, Dundee, Angus, Perth and Stirling. If you have spotted any of the signs above, call us for a free no-obligation quote.