'I have never seen a rat in the area before then': More rat sightings reported amid rainy season

Lisa Tan was soaking in the festivities on Christmas Eve at Gardens by the Bay when an unusual furry critter briefly joined the celebrations, scurrying across the exit of Bayfront MRT station.

"It was unusual, considering it was crowded, and I have never seen a rat in the area before then," said the 56-year-old lawyer.

Four pest controllers The Straits Times spoke to have observed up to 25 per cent more inquiries monthly on rat infestations since November 2023, saying that the rainy wet weather is likely forcing the rodents to seek drier ground.

Head entomologist at Verminator Rachel Kee said: "Heavy rain can flood rat burrows or nests, forcing rats to seek new shelter. This displacement may bring them into more visible or accessible areas."

Managing director of Killem Pest Nicole Zycinski-Singh said that due to the wet weather, rats are forced out of their harbouring areas in search of food and water, as well as a more protected space.

"This is why rats are more attracted to internal areas like houses and other buildings during this time," she added.

Most of the increased rat sightings due to the recent rainy weather would be sewer rats, said Foo Foong Kuan, general manager of technical and entomology at Anticimex: "If sewer rats get inside a building due to rain, they will hide in ceilings, roofs or any void areas."

Roof rats and house mice are the other two common species of rats in Singapore.

While sewer rats are found in burrows and basements underground, roof rats typically nest in elevated locations like false ceilings, attics, and trees, and house mice can be found in dark and secluded areas.

Despite reports of more sightings of rats during this season, Kee said it is not known whether the rat population has increased, because of various factors.

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"The availability of food sources, the type of rat species present, environmental conditions, and the presence of predators all play crucial roles in determining whether heavy rainfall will lead to an increase or decrease in the rat population," she said.

"It's essential to note that rats are resilient and adaptable animals. While flooding may cause a temporary decline in the population, rats can quickly rebound if suitable conditions return."

Moreover, plant growth spurred by increased rainfall could consequently provide more forms of shelter, as well as more food sources for insects, snails, and slugs which, in turn, the rats can feed on, she added.

Another reason the wet weather might not have downsized the rat population — they are nimble. PestWerkz Solutions specialist Edwin Kwek said: "Rats are pretty good climbers and swimmers."

In his 20 years of working at a pest controller, Kwek has witnessed a rat scale about 1m up a wall, and also received an inquiry on a rat being found in the toilet bowl, believed to have ended up there after swimming through sewage pipes.

Zycinski-Singh said: "Rats are smart. They constantly explore and learn."

"They can also memorise the locations of pathways, food, water, shelter, obstacles and features of their environment, and quickly detect and avoid new objects and novel food.

"Therefore, they often avoid traps and baits for several days or more following their initial placement."

To prevent the resurgence of rat populations after the rain, Kee stressed the importance of sanitation, waste management, and guarding potential entry points against rats.

She added that with more unbagged waste in rubbish chutes and bins, it not only provides an easily accessible and abundant source of food, but also materials for nesting.

According to the National Environment Agency's (NEA) website, rats can transmit diseases to humans through direct contact or dust contaminated with rat urine or droppings that is breathed in.

These diseases, such as leptospirosis, murine typhus and hantavirus, could lead to kidney damage, meningitis, liver failure, and fatal respiratory diseases.

Islandwide surveillance is carried out by the NEA to identify areas with rat activity, and to facilitate targeted and sustained control efforts.

The information is shared with other stakeholders like government agencies and town councils for them to carry out preventive and control measures.

In response to The Straits Times' queries on whether the rat problem in Singapore has exacerbated recently, the NEA said it has no updates.

Julie Chia, the 66-year-old owner of a shop selling dry goods in Chinatown Complex, is now more guarded with her goods, covering them all up every time before closing shop.

"Once the rains stop, I hope my efforts to keep the shop clean will pay off and there are fewer rats," she said.

ALSO READ: NEA, SFA to take enforcement action after finding rat infestation at Tangs Market's ceiling

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