Twenty-two inches from quivering whisker to fat tail, they can chomp through concrete and leap more than two feet in the air. Sauntering down your street in broad daylight, insolently raising two claws to the binman, they rifle through your rubbish and scoff poison as if it was milk chocolate. There is something of the night and also something of the urban myth about the nearly indestructible super rat coming to a pile of carelessly discarded foodstuffs near you. But Britain's pest controllers are adamant: they are receiving more panicky reports of rodent infestation than ever, and it does seem that our rats are evolving into something not seen before.
Over the past five years, the number of infestations of Rattus norvegicus, better known as the brown rat, has steadily increased, according to figures collected by the National Pest Technician's Association. Infestation dipped last year by 8% but is widely forecast to rise this year, and the association suspects that the true infestation figure only fell last year because fewer people report incidences now that many local authorities charge for pest control services. Meanwhile, people report bigger, and bolder, rats. Pest control professionals recently reported catching one beast in south London that measured 22 inches long.
So has the creature we know as the sewer rat, the barn rat, the love rat and the lab rat evolved into a new breed of super rat?
"It's not so much [a] super rat in terms of being 2ft long and two stone in weight," says Oliver Madge, chief executive officer of the British Pest Control Association. "Food is the key. They have a better reproduction rate and a better chance of survival. [The new rat is] not super - but it's certainly a strong species coming through because they've got the food and the climate is milder." But the super rat isn't just a healthier, better-fed rat: "Traditional poisons aren't working," says Madge. "They are eating and feeding from the poison. They can consume what we call a lethal dose and it doesn't kill them."
Experts say the main reason for the rise in the numbers of rats is obvious: from the milky bread thrown out for the birds to that carelessly tied sack of Sunday leftovers, we as a society are producing more food waste and chucking it out more carelessly.
The rat are not the only scavenger whose numbers are increasing. It is not quite an ecosystem that has evolved around the rubbish bin but it is not far off, and various species certainly give each other a helping paw when it comes to raiding our trash. Old-fashioned black binbags are easily ripped open by urban foxes or cats, for example, encouraging mice and rats to feast on what is inside. Virtually rodent-proof wheelie bins are a different matter - but this is where the squirrels have a role to play. "It is very difficult for rats to get inside a wheelie bin but squirrels have learned how to flip the lids open if there is a lip on the bin. They are very dextrous," says Madge.
The super rat has evolved thanks to all this dining from the table of man. As people pile high the KFC leftovers and Indian takeaways, and toss away half-eaten megaburgers when their stomachs can't take any more abuse, our ratty friends acquire a symbiotic addiction to rubbishy food. According to Martina Flynn of Sorex, whose scientists have developed three of the four main pest-control chemicals, rodents have become so used to munching protein-heavy fast foods in certain urban centres that they refuse to eat the carbohydrates and cereal traditionally used as bait or poison.
"The rats and mice are forever keeping ahead of us and making it hard for us," says Flynn. She believes that few rodents develop full physiological resistance to poisons, although it does take a bigger dose to kill them off these days, but behavioural resistance is another problem. "Rats are very neophobic - which means they are wary of new objects. You can put a bait down and they won't touch it for 10 days," she says.
Many people blame the rise of the fortnightly rubbish collection for the rise of the super rat. One third of local councils have abolished weekly (or daily) collections of rubbish and pick up nonrecycleable rubbish only once every two weeks. For residents unable to keep their wheelie bins safely stowed in the backyard, this means that there are plenty of ways their rubbish can be scattered far and wide during the long wait for collection.
In one area, a council official reportedly advised residents to freeze their roast-dinner carcasses until collection day. It caused outrage but sounds sensible enough. As it happens, councils are not legally required to collect rubbish every week, and the government has no plans to force the issue. And expert opinion agrees a weekly collection is not necessary, provided the proper precautions are taken.
"It is not essential from a health-risk point of view in this country for rubbish to be collected once a week," says Howard Price of the Chartered Institute of Environmental Health. "Fortnightly collections may be adequate but only if the containers provided are big enough and properly lidded so that the waste is safely contained and does not spill out. It must also be collected promptly and efficiently with no spillage on to the street during collection."
If you are under siege from the super rat, there is one place you could go. This time last year, the Hebridean isle of Canna had a human population of 11 and a rat population of nearly 10,000. The rats had gnawed through supposedly rodent-proof composters and seriously damaged bird populations. The National Trust for Scotland called in a team of ratcatchers from New Zealand. When food was scarce last winter, 14 catchers laid 4,200 bait stations filled with a low-toxicity bait rarely used in Europe. Wheelie bins were also introduced and residents agreed not to keep chickens (whose scattered food the rats enjoyed nibbling). "The last confirmed rat presence was in February," says Richard Luxmoore of the trust. "I'm not saying we've completely got rid of the rats but if there are any left we've got remarkably few ".