In search of the giant rat

Are plagues of huge rats really overrunning the UK? There was only one way to find out…

Emine Saner
guardian.co.uk,
Sunday 19 September 2010 20.30 BST

Mac Hussain disappears into the undergrowth. "Mind out, there's broken glass there," comes his voice from the other side of some brambles. Between short rain breaks in the sodden sky, we are on the hunt for giant rats. There are thought to be at least four here – well that's what Brandon Goddard told the Sun recently, after it ran a picture of him holding a giant rat he claimed to have shot on this Bradford estate. "The first went right past but we got the second one. Then three more got away," Goddard, who lives in nearby Wakefield, told the paper. "This one I shot was absolutely terrifying. I was shaking. Goodness knows where the others went."

Thankfully, there is no sign of them now – but if you heard that a Sun reporter and a man with an air rifle were on your tail, would you hang around? We poke about in the undergrowth on a bit of wasteland. "Ideal place for rats, this," says Hussain. He has been a pest controller for 12 years. "There has been so much rain over the last few weeks that it will have had an effect, physically pushing the rats out of the sewer system."

Last month, Yorkshire Water warned of just such an increase in the number of rats in Bradford. The company, which baits around 100,000 of its manholes, reported a rise in "takes" (poison disappearing from bait boxes). A spokes-man put this down to households and food businesses pouring cooking oil down the drains, where it congeals in the sewers and the rats feed on it.

"I think the numbers are increasing," says Hussain. "I'm certainly getting more calls." He thinks several factors are at work: "Bin collections are getting less regular, there are more takeaways opening, and people throw so much food away now. The [rats'] size does seem to be getting bigger compared to when I started out."

But he is not convinced that so-called giant rats exist. "If you get a well-fed rat, it can be 15 inches – plus the tail can be seven or eight inches. And people always think a rat is bigger than it is. I get a panicky call from someone saying they've seen a huge rat, and it turns out to be a mouse." The biggest rat Hussain has ever caught was 14 inches (not including the tail). "If you stretched it out, you could probably get it to two feet."

Every year there are stories of towns and villages that are supposedly "rat infested". This summer it was Haltwhistle in Northumberland. Last year, it was Flamborough in Yorkshire and two unidentified Berkshire towns that were becoming "overrun". A woman, who asks not to be named, stops to watch. "I think it's a load of rubbish," she says. "I've been here four years and never seen a giant rat. It's wrong to say we're being invaded."

There was some speculation that the giant rat Goddard claimed to have shot was actually a coypu, a South American rodent sometimes kept as a pet. But we can't find any coypus either. Later, when I consult Stephen Battersby, a rat expert and president of the Chartered Institute of Environmental Health, he inclines towards the coypu suggestion. But does he think rat numbers are increasing? "The indicators appear to be that they are, but there is also a natural population cycle, so it's hard to know."

What is certain is that rats have a serious image problem. Personally, I quite like them, but for most people – fed by horror-film imagery and the fact that rats are always blamed for the plague (it was actually the fleas they carried that were responsible) – they are the stuff of nightmares; think of the rats in Room 101 trying to gnaw away at Winston Smith in Orwell's 1984. Mice, though still considered vermin, are at least seen as fairly cute.

Putting a figure on the number of rats in the UK is difficult. It is often claimed there is one rat for every person, meaning there are more than 60 million. "That's a myth," says Battersby, explaining that this came from an estimate of the rat population just after the first world war, when there were fewer people and farming practices included building hay ricks where rats thrived. "Life has changed a great deal since then. I would say there could be in the order of 20 million. But if you have rats in and around your home, it doesn't matter what the number is in the rest of the country, it's those you have to worry about."

Rats can get in "through a gap as small as half an inch," says Battersby. "They can flatten themselves. They're also extremely clever, and can swim and jump." Hussain says they also burrow under foundations. "I've seen holes chewed in walls, concrete gnawed through. The damage they do is unbelievable. People don't want to admit they have a rat problem – it sounds as if they are dirty – but rats will come in if there's access and there's food lying around. If you're feeding the birds, that's a really good source of food. So is home composting."

Rats are not great climbers, but they can shimmy their way up a house in the gap between drainpipe and wall, then get into the roof. "A common route is through ruptured drains or poorly covered drains," says Hussain. My friend, Helen, came home from work one day and heard a splashing noise coming from her downstairs loo – there, treading water in the toilet bowl, was a wet rat. She left London shortly afterwards. "I've seen plastic pipes on the back of a toilet chewed through," Hussain confirms.

Neither the black rat, which is all but extinct now, nor the brown rat are native to the UK. It is believed the black rat came to this island with the Romans, and the brown rat in the 17th century as trade and shipping grew. Rats have travelled all over the world as stowaways on boats, colonising their destination. And, of course, they carry health risks to humans. "Leptospirosis [Weil's disease] is relatively rare," says Battersby. "But if you're taking part in water sports or go fishing, make sure you don't have any open cuts. If you're working in the sewers, the same. But for the general public, it's not really the issue."

More problematic, he says, are the parasites that rats often carry. These include cryptosporidium, which causes diarrhoea, Toxoplasma gondii, which can be fatal to unborn children, "and a lot of worm infections, which can cause stomach problems. There is certainly an association between rat allergen and asthma. Rats excrete salmonella as well, and potentially E coli."

Richard Moseley, from the British Pest Control Association, says rodents are also to blame for some house fires, "because they chew through electric cables". Rats that chew through cables on the rail network cause obvious problems, and getting a rat trapped in a piece of machinery in a factory means production can be stopped for days. "That's a lot of manufacturing you've lost."

Now pest control experts warn that we could be on the brink of an explosion in the numbers of rats as local councils, strapped by budget cuts, put vermin control low down their list of priorities. An even bigger threat, says Moseley, are proposed EU changes to the use of rodenticide. "There are going to be some restrictions, but we're not sure what those are going to be yet."

There are also suggestions that rats are becoming resistant to rodenticides. Robert Smith, a retired professor, is working on a survey of rats from around six areas of the UK that have become resistant to anticoagulant, the main rodenticide used by pest controllers. "People have been trying to deal with rats for centuries," Smith says. "They used to use toxic plants to poison them, but rats evolved behaviour to counteract that. They developed 'taste aversion'. They are neophobic – they have a fear of anything 'new' – so with a new food, they won't gorge themselves on it, they will just nibble, then go away and see if it harms them. Rodents can't vomit; once they've swallowed something they can't get rid of it, so they are very careful. If something makes them feel ill, the memory of that taste stays with them for their lifetime." What's more, he says, rats can communicate this information to other rats, probably through scent on their breath. "That makes it difficult to kill a rat with anything that makes them feel ill quickly."

This is where anticoagulant rodenticide comes in – preventing blood clotting so a rodent, squeezing through tiny gaps and picking up small injuries, effectively bleeds to death internally. More importantly, rodenticide are slow-acting, so the rat never learns to associate the bait with what is killing them. They were introduced around 1950 and, by 1958, scientists found the first record of resistance. "In the 70s, chemists devised new versions of the anti- coagulant that overcame resistance so it looked like problem solved." It wasn't though. By the early 90s, rats in southern England were displaying signs of resistance. "There are now parts of Berkshire and Hampshire where it seems it's not possible to control the rats, not with chemicals that are legal to use."

How long will it be before the entire rat population is resistant? "It really depends on how extensive resistance is, and how quickly it spreads – we just don't know at the moment," admits Smith, who is aiming to have all the samples in by the end of April. If all rats became resistant to anticoagulants, he says, "I guess we would be back to where we were during the 40s. There would be significant amounts of contamination of food – we would have to get used to rat droppings and hairs in food. Then there are the diseases that can be spread to other animals, including livestock and people." And if rats are getting bigger, he says, it could be that they have genetic resistance, "which means they live longer – rats keep growing".

Hussain and I drive to an area of Bradford to which he has been called out before. Mohammed, who runs a taxi company at the end of a residential street, says he has a problem with rats. "There's one we see that's the size of a small cat, but it always gets away. We put those glue traps down." Mohammed says it was caught but managed to escape, leaving hair stuck to a pad like someone freeing themselves of their trousers.

He takes us to a room at the back of his office and the first thing you notice are all the holes in the ceiling. "They go in the ceiling to die and it really stinks." He made the holes in the plasterboard to cut them out – it looks like the work of someone driven demented by rats. "I think they came from the restaurant next door, until it closed down. I looked in the window once and there were five or six rats in there. They're not scared."

Back in the car, Hussain explains how he rids a house of rats. He uses boxes baited with anticoagulant; traps don't tend to work. "You're talking about an intelligent animal – if something is killing its friends, it will stay away," he says. After a week or so, he returns to look for the bodies and remove them for incineration.

I'm starting to feel a bit sorry for rats. I had one - his name was Geronimo – when I was a child, so I know they are intelligent, affectionate animals. And if rats are on the increase, it is surely our fault. We tempt them into our homes and workplaces with the shameful amount of food we throw away. "We don't have an active rat population without human activity," says Battersby. "If people throw food litter around, or don't store their refuse correctly, don't be surprised if you get rats. The way rats behave are usually a reflection of the way we behave."

As the sky darkens again, we are forced to give up the search for giant rats. I've been trying to work out if Hussain actually likes rats, or feels a bit sorry for them, but he won't bite. Eventually, as we drive to look at a bait box outside a fried-chicken restaurant, he admits to a grudging respect. "They are a formidable adversary," he says.

http://www.guardian.co.uk/environment/2010/sep/19/in-search-of-giant-rat