A rodent problem does not usually begin with a rat suddenly running across the kitchen floor.
By the time that happens, there may already be activity hidden behind a wall, under a cabinet, or somewhere around the outside of the property.
Rodents tend to move along walls and stay away from open spaces. They also become more active when the surroundings are quiet. The good news is that they leave clues. Droppings, greasy marks, damaged packaging and nesting material can all reveal activity before a sighting.
Singapore’s rodent situation shows why spotting these signs early is useful. NEA’s two-monthly surveillance recorded an average of about 3,400 rat burrows per cycle in the first half of this year, down from roughly 5,400 during the same period last year. Most of the burrows were found in public housing estates, followed by grass verges along roadsides and industrial areas.
NEA has also highlighted the role of food and shelter. When these remain easily available, rodent populations can recover quickly.
For homeowners and businesses, knowing what to look for is a practical first step.
The 15 Signs of Rodent Activity at a Glance
| # | Sign | Where to look | What it may indicate |
| 1 | Droppings | Cabinets, under sinks, behind appliances | Current rodent activity |
| 2 | Grease or rub marks | Skirting boards, wall bases, corners | A regular travel route |
| 3 | Gnaw marks | Wood, plastic, pipes, cables | Ongoing rodent activity |
| 4 | Shredded nesting material | Storerooms, ceiling voids, behind cupboards | A nearby nest |
| 5 | Tail marks and footprints | Dusty floors, shelving, ledges | Recent movement |
| 6 | Chewed food packaging | Pantries, rice sacks, dry goods storage | Feeding activity indoors |
| 7 | A rodent seen in daylight | Anywhere on the property | Possible heavy activity or overcrowding |
| 8 | Scratching sounds at night | Ceilings, wall voids | Rodent activity inside the structure |
| 9 | Musky ammonia-like smell | Enclosed spaces, behind appliances | Heavy or prolonged activity |
| 10 | Pets repeatedly focusing on one area | Skirting, cabinets, ceilings | Possible hidden activity |
| 11 | Gnawed holes in walls or skirting | Corners, behind furniture | A route between shelter and food |
| 12 | Damaged wiring | Ceiling spaces, behind appliances | Electrical and fire risk |
| 13 | Urine stains and soiled insulation | Ceiling boards, stored items | Contamination and property damage |
| 14 | Burrows outside | Soft soil, drains, shrubs | An outdoor rodent colony |
| 15 | Runways and gnawed bin lids | Vegetation, refuse points | An established food source |
Signs You Can See Indoors
#1 – Rodent Droppings
Droppings are one of the easiest signs to spot and one of the first things a pest professional will look for during an inspection.
Do not expect to find them scattered across the middle of a room. Rodents prefer protected areas, so check behind appliances, inside cabinets, under sinks and along less disturbed parts of the property.
The size and shape can help distinguish mice from rats:
| Rodent | Typical droppings | Appearance |
| Mouse | About 3 to 6 mm | Smaller and tapered at the ends |
| Rat | About 12 to 19 mm | Larger with blunter or more rounded ends |
Fresh droppings are usually dark and slightly glossy. Older ones tend to become dull, grey, and crumbly.
Finding newer and older droppings in the same area can suggest that the activity has been going on for some time.
There is one more thing to keep in mind: do not sweep or vacuum rodent droppings. Disturbing them can send contaminated particles into the air. Wear gloves, handle the waste carefully, and disinfect the area afterwards.
#2 – Grease and Rub Marks
Look at the lower edges of your walls.
When rats repeatedly travel along the same route, oil and dirt from their fur can leave dark marks on skirting boards, wall bases, and corners. You may also notice these marks around gaps or openings they use to move between areas.
These stains are more useful when they appear with other evidence. For example, a grease mark beside fresh droppings is much harder to dismiss as ordinary dirt.
#3 – Gnaw Marks
Rodents need to gnaw because their incisors continue growing throughout their lives.
That habit can leave some obvious damage.
Mice tend to leave smaller, shallower marks. Rats can cause more serious damage to wood, plastic, cardboard, pipes, and cables. Check cupboard edges, door frames, plastic piping, and stored cardboard for fresh chewing.
The location of the damage can tell you something, too. Marks close to food storage or small openings may show where rodents are feeding or passing through.
#4 – Shredded Nesting Material
Found bits of torn paper or fabric in a place where they clearly do not belong?
Rodents may be carrying these materials away to build a nest.
Quiet areas are the first places to check. Think storerooms, ceiling voids, the backs of cupboards, and spaces behind built-in units.
A nest can look like a loose pile of shredded paper, fabric, cardboard, or insulation. You may also find droppings or shed hair nearby.
#5 – Tail Marks and Footprints
Sometimes the floor gives them away.
Dust can make rodent movement much easier to spot, especially in an unused storage area or on a shelf that is rarely disturbed. You may see tiny footprints or a clean path through the dust. In some cases, there is also a thin line where a tail has dragged across the surface.
Outside, the evidence can look different. Regularly used paths through grass may appear smoother or more compacted than the surrounding vegetation.
A suspected route can also be monitored with a thin layer of flour. Check the area the next morning for tracks.
#6 – Chewed Food Packages
A gnawed rice sack or torn cereal box is hard to miss. But the damage may be hidden if food is stored against a wall or in a packed cupboard.
Check behind and underneath dry goods. Look for small holes, torn corners, and spilled contents.
Rodents may chew packaging to get to the food inside. They can also damage packages while exploring, so a chewed box does not automatically mean the contents were eaten.
#7 – A Rodent Seen During the Day
A daytime sighting deserves attention.
Rats and mice are generally more active after dark and tend to avoid exposed areas. When one appears during the day, it may be searching for food or shelter because the usual hiding places are no longer sufficient.
A single sighting does not tell you how large the problem is. It does, however, give you a reason to inspect the area carefully for droppings, nesting material, grease marks, and other signs.
Signs You Can Hear and Smell
#8 – Scratching and Scurrying After Dark
Sometimes the first clue is not something you see at all.
You may hear scratching, scampering, or light thudding from above the ceiling, inside a wall, or in another enclosed part of the building. These sounds can indicate rodents moving through or nesting inside the structure.
Pay attention to where the noise is coming from. Roof rats are good climbers and can use elevated spaces, so activity in a ceiling area can provide a useful clue about where to investigate.
#9 – A Musky, Ammonia-Like Smell
Rodent urine and droppings can create a stale, musky odour. The smell may become more noticeable when activity is concentrated in an enclosed area such as a ceiling void, wall cavity, or the space behind a large appliance.
A strong smell does not always mean there are live rodents nearby, though.
A sudden, very foul odour can indicate a dead rodent trapped inside a wall or another inaccessible area. That is a different problem and may require a different response.
#10 – Pets Repeatedly Focusing on One Area
Your pet cannot tell you what it hears. It can sometimes show you.
A cat or dog that keeps sniffing, staring at or scratching the same section of skirting, cabinet, or ceiling may be responding to sounds or smells you cannot detect.
This is not proof of rodents. Treat it as a clue. If the behaviour continues, inspect the area and look for other signs.
Signs of Property Damage
#11 – Gnawed Holes in Skirting, Walls, or Floors
Rodents do not only chew for the sake of chewing. Gaps can give them access between shelter, food and other parts of a property.
Check corners, areas behind furniture, and spaces near appliances. Small openings can become regular routes, especially when they connect one sheltered area to another.
If the same section keeps showing new damage, that may suggest repeated use rather than a one-off incident.
#12 – Damaged Wiring and Unexplained Electrical Faults
Rodents can chew through electrical cable insulation. That creates a problem far more serious than a damaged wire.
Exposed conductors can cause electrical faults and increase the risk of fire. Flickering lights, repeatedly tripped circuits, or an appliance that suddenly stops working should therefore be investigated rather than ignored.
Rodent activity may be one possible cause, but it should not be assumed without checking.
Where wiring is involved, use a qualified electrical professional for the necessary inspection and repair.
#13 – Urine Staining and Contaminated Storage
Rodent urine can soak into absorbent materials and leave visible stains.
Ceiling boards, cardboard boxes, stored paper, fabric, and other soft goods can all be affected. When urine or droppings have penetrated deeply, cleaning may not make the material suitable for reuse.
The damage can add up. A rodent problem that initially looks minor may eventually lead to contaminated stock, discarded belongings, or repairs.
Signs Around the Outside of Your Property
#14 – Burrows Near the Perimeter
Do not stop your inspection at the front door.
An outdoor burrow may indicate that rodents are living close to the building and using the surrounding area for shelter. Norway rats can dig in soft ground around building perimeters, dense shrubs, poorly drained planters, compost areas, and overgrown sections.
Look for relatively smooth openings, often around 5 to 8 cm across. Loose soil around the entrance is another clue.
An outdoor source can keep sending rodents back to a property. Treating the inside without addressing nearby harbourage may therefore give only temporary relief.
#15 – Runways Through Vegetation and Gnawed Refuse Bins
Look at places where food and shelter are easy to access.
Repeated paths through vegetation, damaged bin lids, and rubbish scattered around refuse collection points can all indicate regular rodent activity.
Poor refuse management is also a major concern in Singapore’s efforts to control rats.
This is a good time to check possible entry points around the building. Look at doors, service pipes, vents, air-conditioning penetrations, and other structural openings.
A mouse can squeeze through a gap of about 6 mm, roughly the width of a pencil. Rats need slightly more room.
How Serious Is the Problem?
No single sign can tell you exactly how large an infestation is. The combination of signs gives a better picture.
| Level | Signs commonly found | What this may suggest |
| Early | A few droppings in one area, minor gnaw marks and no obvious noise | Possible isolated activity or an animal still exploring the property |
| Established | Droppings in several areas, grease marks along a route and repeated nighttime noise | Regular movement with possible nesting nearby |
| Advanced | Nesting material, persistent odour, daytime sightings, extensive chewing and property damage | A larger or established population that may be breeding |
Rodents can reproduce quickly. Rats may reach sexual maturity at around two months, have a gestation period of about three weeks and mate again relatively soon after giving birth.
That gives a small problem plenty of room to grow.
The longer signs are left unchecked, the more difficult it can become to identify and address the source.
Why Rodent Activity Is A Cause of Concern
Rodents are more than a nuisance. They can create health, hygiene, and compliance issues for homes and businesses.
Health Risks
A study involving 1,143 rodents across 10 landscape types in Singapore found that 42.4% carried Leptospira bacteria. The study also found 35.5% were seropositive for Seoul hantavirus, and 32.2% for Rickettsia typhi, the organism associated with murine typhus.
Most of the rodents were trapped in public residential developments.
These findings provide local evidence of pathogens found in rodents in Singapore and show why rodent control is not simply about keeping premises clean or avoiding property damage.
Compliance Concerns for Businesses
For businesses, rodent activity can also become a premises management issue.
NEA and SFA jointly took around 1,300 enforcement actions against premises owners for rat-related lapses in a single year after enforcement was tightened. Around 620 of these involved poor refuse management.
Under the Control of Vectors and Pesticides Act, a first offence carries a fine of up to S$20,000, imprisonment of up to three months, or both. For licensed food premises, NEA may also order operations to stop until the infestation has been resolved.
Rodent control should therefore form part of regular premises management, especially for businesses where food and refuse are present.
What Should You Do If You Spot These Signs?
Step 1: Record what you find
Take clear photographs and note where each sign appeared.
The location is useful. Droppings behind a refrigerator tell a different story from droppings beside an outdoor bin, for example.
Step 2: Remove accessible food sources
Keep dry goods in secure containers. Clean up spills and make sure refuse is properly contained.
The less food rodents can access, the fewer reasons they have to remain in the area.
Step 3: Do not seal every opening immediately
It may seem logical to block every gap as soon as you find one. But sealing an active route without understanding how rodents are using it can push them further into the structure.
In some cases, an animal may then become trapped inside.
Step 4: Check the outside as well
An indoor inspection is only part of the picture.
Look for outdoor harbourage, food sources, and possible entry points around the building. If the source remains outside, indoor treatment alone may not solve the problem.
Step 5: Be cautious with supermarket rodent baits
Off-the-shelf bait may not address the underlying cause when there is an established infestation.
Rodents can become cautious around unfamiliar objects and food sources. Poor bait placement can also mean the animals simply do not encounter it.
An inspection can help identify where rodents are travelling, feeding and nesting before treatment begins.
Frequently Asked Questions About Rodent Infestations
What is the most common sign of rodents in a home?
Droppings are one of the easiest signs to find. Their location, amount, and appearance can also provide useful clues about whether activity is recent or ongoing.
How do I tell rat droppings from mouse droppings?
Mouse droppings are smaller and usually pointed at the ends. Rat droppings are larger and generally have blunter ends.
Size and shape can help with identification, although professional advice is useful when you are unsure what you have found.
Does seeing one rat mean there are more?
Not necessarily. But a sighting should still be investigated.
Rodents generally avoid exposed areas and are more active at night. A visible rat may indicate that there is nearby shelter, food, or an established route that has not yet been identified.
Can I handle a rodent problem myself?
It may be possible to catch an isolated rodent using basic control measures.
The bigger issue is what happens afterwards.
If the nest, food source, or entry point remains, more rodents may continue to enter the property or stay in the area. Finding and addressing the source is often more important than removing the one animal you happened to see.
Do rats in HDB blocks come from inside or outside?
Rodents can move between indoor and outdoor areas depending on the building and surrounding environment.
NEA surveillance has found many rat burrows in public housing estates, highlighting the role of outdoor harbourage around residential areas.
This means treating only the inside of an HDB flat or building may not be enough when nearby food sources, harbourage or entry points remain.
Getting a Rodent Problem Checked
Rodent activity rarely announces itself clearly.
It may start with a few droppings behind an appliance. Then comes a greasy mark along the wall. Perhaps there is scratching from the ceiling late at night.
Each sign may seem minor on its own. Taken together, they can tell a very different story.
A professional inspection can help establish where rodents are entering, which routes they are using and whether an outdoor source is contributing to the problem.
Avalon Services offers a free preliminary consultation and inspection, with NEA-registered technicians, human-safe products and a warranty on completed work.
If you have noticed signs of rodent activity at home or on your premises, having the source checked early can help prevent the problem from becoming more established.
