Tuesday, May 18, 2004
Rats like banana -- enough to sniff out land mines
Rodents show great promise in detecting buried TNT, and they don't set
it off
By MICHAEL WINES
THE NEW YORK TIMES
GONDOLA, Mozambique -- Just about every method of detecting land mines has a drawback.
Metal detectors cannot tell a mine from a tenpenny nail. Armored bulldozers work well only on level
ground. Mine-sniffing dogs get bored, and if they make mistakes, they get blown up.
The Gambian giant pouched rat has a drawback, too: It has trouble getting down to work on
Monday mornings. Other than that, it may be as good a mine detector as man or nature has yet
devised.
Just after sunup on one dewy morning, on a football-field-sized patch of earth in the Mozambican
countryside, Frank Weetjens and his squad of 16 giant pouched rats are proving it. Outfitted in tiny
harnesses and hitched to 10-yard clotheslines, their footlong tails whipping to and fro, the rats lope
up and down the lines, whiskers twitching, noses tasting the air.
Wanjiro, a sleek 2-year-old female in a bright red harness, pauses halfway down the line, sniffs,
turns back, then sniffs again. She gives the red clay a decisive scratch with both forepaws. Her
trainer, Kassim Mgaza, snaps a metal clicker twice, and Wanjiro waddles to him for her reward -- a
mouthful of banana and an affectionate pet.
"What Pavlov did with his dogs is exactly what we're doing here -- very basic conditioning," said
Weetjens, a lanky, 42-year-old Belgian who works for an Antwerp demining group named Apopo.
"TNT means food. TNT means clicking sound, means food. That's how we communicate with
them."
Wanjiro has been rewarded for sniffing out a TNT-filled land mine, one of scores buried a few
inches below ground in the training field where she works out five days a week. Like all the
training mines, this one was defused. But if the Mozambican authorities approve, she and her
companions will move at year's end from dummies to live minefields -- the world's first certified,
professional mine-detecting rats.
"Animal detection, with dogs in particular, has increased very much in the last three or four years,"
said Havard Bach, the top expert on demining methods for the Geneva International Center for
Humanitarian Demining. But in many cases, he said, "it would probably be better to use rats than
dogs."
Rats are abundant, cheap and easily transported. At 3 pounds, they are too light to detonate mines
accidentally. They can sift the bouquet of land-mine aromas far better than any machine. Unlike
even the best mine-detecting dog or human, they are relentlessly single-minded.
"Throw a stick for a dog to fetch, and after 10 times the dog will say, 'Get it yourself, buddy,' "
Weetjens said. "Rats will keep working as long as they want food."
Plenty of work awaits them. The
International Campaign to Ban Land
Mines estimates that 100 million
mines have been laid worldwide,
from anti-personnel and anti-tank
mines hidden underground to
above-ground mines triggered by
tripwires. Although Mozambique's
civil war ended nearly 12 years ago,
sappers here still discovered and
destroyed more than 10,100 mines
last year alone, and mine explosions
killed or injured 14 people.
Experts say that the pace of
land-mine detection has slowed
globally in recent years, in part
because the death of its celebrity
spokeswoman, Princess Diana, has
robbed the cause of publicity and
support. But there is also a shortage
of land-mine specialists and a true
dearth of sure-fire methods to find buried mines.
Human detection -- steel-nerved workers with metal detectors and probes -- remains the preferred
technique. But metal detectors are hard put to distinguish mines from other metal objects and even
from some non-metals, like mixtures of dirt and charcoal. Moreover, in areas where exploded
mines have scattered metal fragments, rooting out false readings can be daunting.
Dogs, with their strong noses and affinity for people, are increasingly popular; about 200 are
working now in heavily mined Afghanistan. But they are hard to keep healthy, especially in tropical
Africa. They tend to bond with trainers, making it hard to switch them to another handler.
And they so badly want to please that a simple misreading of their trainers' body language can lead
them to indicate a mine's presence where none exists or, far worse, ignore a real one.
Then there are rats, which don't give a fig about people but will do anything for bananas and
peanuts. "All a rat wants to do is find the target and get his reward," said Bach, of the Geneva
demining center. "They're almost mechanical in the way they work."
Mine-sniffing rats are the sole focus of Apopo, a Flemish acronym for "product development
geared toward the demining of anti-personnel mines." The group is the brainchild of Weetjens'
brother Bart, a college friend, Christophe Cox, and a University of Antwerp professor, Mic Billet,
now Apopo's chairman.
The three decided in the late 1990s that so-called biosensor animals with great noses were the future
of land-mine detection, but that there must be creatures better suited for the task than dogs.
With a grant from the Belgian government, they began hunting for an animal with a dog's sense of
smell, but none of its drawbacks. They approached Ron Verhagen, the head of the university's
biology department, for help. "And that," Weetjens said, "is where rats came along."
More specifically, along came Cricetomys gambianus, also known as the Gambian and African
giant pouched rat. Up to 30 inches long, it thrives in most of sub-Saharan Africa, lives up to eight
years in captivity and is "savage" in the wild, Weetjens says, but so docile when bred that some
people keep them as pets.
Most important, the pouched rat (so named because it stores food, hamster-style, in its cheeks)
buries what it does not immediately eat and sports a nose honed to bloodhound status by aeons of
searching for buried food stashes. Persuading the giant pouched rat to hunt for land mines is as
simple as convincing him that TNT is just another tasty treat waiting a few inches underground.
Each rat gets to sweep a 10-by-10-meter square of land on which two defused mines or TNT scents
have been hidden. Finding the mine or scent earns a click and a bite of banana or peanuts. Failure
generally earns a second try. Some rats try to game the system, scratching the earth randomly in
hopes of free treats. But the trainers feed them and sound a click to signal success only when they
scratch the right spots.
Bananas and peanuts, after all, are what drives the pouched rats to excel. Which is why they are
often at their worst on Monday morning.
"During the week, they're on a diet. They have to work for their food," Weetjens said. "But on
weekends, they get to eat as much as they want. On Mondays, they just aren't as hungry." |
