Rats Thrive

"Snakes," said Mr. Romer, Hong Kong Urban Services Pest Control Officer, "are my personal interest." But he admitted that, from the point of view of his job, rats were more important.

Had he an affection for rats? "I would not call it affection. I'd call it admiration: admiration for an adaptation to a commensal (living with or off man) environment. Consider the vast amount of research and money spent on trying to control rats; yet they still don't just survive, they thrive. I can't give you figures for Hong Kong; you just can't do it. You can estimate in a small or confined situation. To estimate for the Colony is so unrealistic; it's not worth doing.

"There are three main species of domestic pest. One: the Common or Norway Rat, sometimes known as the sewer or brown rat. Two: Buff-breasted Rat: this is a South Chinese indigenous race of the black or ship rat. Three: the house mouse: it's very, very interesting how this species has developed; when I came here in 1946 it was virtually unknown—now we collect thousands.

"In 1946 the rat was having a heyday and the mouse could not compete. Then came the high-density buildings and concrete construction. In these conditions the rat couldn't compete and the mouse could. It's possible for the mouse to live where the rat can't; and, because it's small, people don't bother about it too much. The rat was driven away by the habitat change, and the mouse finding an ecological niche, replaced it."

We asked if any rats in Hong Kong were proving resistant to Warfarin, the anti-coagulant poison that causes them to bleed to death. (On the borders of England and Wales there are rats that now devour Warfarin greedily and suffer no ill-effects.)

"We're keeping an eye on that here," Mr. Romer said. "But we've had no cases of it so far. There's a special World Health Organization test kit. It's something we've really got to watch because we've been using Warfarin for many years."

We remarked that the noted British scientist Professor J. B. S. Haldane had once said that if man, through his own folly, wiped himself out, the sage rat might one day take his place and even surpass him in ingenuity

"I don't see why it should," said Mr. Romer. "It's just a highly successful commensal rodent that's done very well—except in very cold regions."