We may not like rats, but we do a good job of making them feel at home
- Far from being a particularity in Hong Kong, rodent problems are a fixture of urban environments the world over
Numerous thoughts rushed to mind. First, I had to scour my brain to remember what I had written. Rats, after all, are not something I write or think about often. Second, I was pleased to discover that someone was reading my column – especially one written over five years ago.
Third, how come so little has been written about Hong Kong’s rats in the past five years that this journalist needed to resort to my ancient article? But perhaps most important and depressing of all, why is it that so many so often think of Hong Kong only in negative terms? For sure, that Singaporean news team will be hoping that however bad their city’s rat problems might be, Hong Kong’s will surely be worse.
Thinking back to my 2019 research on rats, I am reminded of how hard it was back then to discover the world’s rat population or their numbers in the world’s major cities. Rats don’t exactly queue up to be counted, and data is imprecise. I recall one note unhelpfully observing that “everyone agrees [brown rats] outnumber us - but no one seems eager to count”.
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Fighting Hong Kong’s rampant rat problem
Paris reportedly has 6 million rats – around three times the city’s population. Its infestation is on a par with New York and London. In the wake of the Covid-19 pandemic, UK researchers estimated that Britain is home to 150 million rats. But the lack of reliable data makes the subject very vulnerable to bias and prejudice.
What we overlook is that it is the rat’s dubious qualities that set us humans apart too. As Emma Marris recently wrote in National Geographic, “Their filth is really our own: In most places, rats are thriving on our trash and our carelessly tossed leftovers.”
So my answer to the producer’s team was that rat populations are intrinsically linked with urbanisation: the more people, the more rats, wherever in the world you look. Singapore is unlikely in empirical terms to be suffering a surging rat population, except in so far as its own human population is growing. Nor is Hong Kong likely to have a disproportionately denser rat population.
Some cities will seem to have more rats. Richer communities may produce more food waste, and sloppy management of that food waste gives rats an opportunity to thrive, but their visibility may have as much to do with the quality of the urban infrastructure than with the size of their population. More and better-built underground tunnelling for drainage, sewerage or cabling makes it easier for rats to move around unnoticed.
New York-based “rodentologist” Bobby Corrigan noted that when rats are poisoned in one area, the survivors simply breed until the burrows are full again. And breeding is something rats do remarkably well.
A rat can gestate a new litter of up to 12 pups in 21 days and up to six litters a year. That suggests a single copulating couple can increase the population by over a thousand within a year. In Hong Kong, our Food and Environmental Hygiene Department says Mong Kok, Sham Shui Po, Wan Chai and Eastern district are among our most troublesome hotspots.
David Dodwell researches and writes about global, regional and Hong Kong challenges from a Hong Kong point of view
