THE GREAT RAT RACE

SUSAN TIPPIE is gently cradling a sample of her company's hottest property. "R04 Jumbo Rat, 7in plus-plus-plus - $3," she says proudly. As the gray-and-white Rattus norvegicus nuzzles her neck, she tells me, "We sell an average of 20,000 to 25,000 rats and mice a week." Lately, though, she continues, customer demand has been running at nearly twice that, and this is why the United States is suffering a national rat shortage.

That comes as bad news to the 20 million Americans who have to find something to fill the gaping maws of their pet snakes and other reptiles. In recent years, says Kraig Adler, a biology professor at Cornell University in New York, "the 'herps' [short for herptile, meaning reptiles and amphibians] have come on like gang-busters - the low-maintenance pet of choice for busy adults and kids alike".

What used to be a handful of businesses catering to a small straggle of enthusiastic backyard rodent-raisers has somehow turned into a $235m- a-year (pounds 150m) industry, complete with air-conditioned breeding rooms, Internet catalogues and competitors scurrying to expand. About 93 per cent of America's 180 million rats and mice raised this year will be sold as reptile food - and that's still not enough prime vermin. (Another 2 per cent are sold as pets; the rest are destined for research laboratories.)

David Loupe, an auditor at an aircraft company in Los Angeles, currently has seven monitor lizards and 13 snakes in his garage, along with 70 incubating bearded dragon eggs. "My monitor lizards have hearty appetites, especially the five-footer," he says. "I had to call rodent dealers all the way to Florida last week, and was turned down by the first six - just to buy 1,000 frozen mice." One of the breeders who refused Loupe's order was Jim Dykes, owner of the Pied Piper rat and mouse farm near Knoxville, Tennessee, and a former reptile keeper at the Knoxville Zoo. "I have to make sure there's enough for my regular customers," he explained.

Some rat breeders are responding to the growing demand by raising their prices. "Some people joke about a rat shortage, but it's true," says Dick Phelan, a marketing supervisor at SAS Supply, a rodent breeder in upstate New York. His company plans a price increase of up to 5 per cent this month, when millions of baby snakes will hatch in terrariums around the nation. Like nature, this business requires adaptability.

Susan Tippie is the general manager of D&H Pet Farms Inc (the name is to protect against angry neighbours and animal activists). The company started out by breeding hedgehogs, briefly a fashionable pet until people tired of their prickles. At that point Susan Tippie turned her attention to what are known in the trade as "prey mammals". "Your best rat or mouse isn't necessarily a fat one," she says. Raising rodents can be a dicey business. They won't mate if the air-conditioning is too high; yet if they get too hot, they die. Tippie's rats stay lean on a high-fibre diet that includes beet pulp and wheatgerm, which means they make healthier reptile food. "It's like someone who wants the best for their Mercedes," she explains. "They don't want junk parts." And predators can be picky: the more delicate reptiles are only able to digest the "pinks" (newborn rodents) and the "fuzzies" (those about 10 days to three weeks old). A large adult rodent, served alive, may gnaw a snake to death.

While some buyers are willing to take frozen rats, which can be stockpiled, shipping costs often make them more expensive than the live ones. Besides which, many reptiles insist on a live or freshly killed meal. "You can train them to eat thawed-out frozen, but some owners won't take the time," says Toby Cromwell, a herpetologist at Reptile World Serpentarium near Orlando. Anyway, he says, many reptile owners love watching the attack. "The snakes don't need that, but it fascinates a lot of people."

At the moment, evidently, a wave of so-called "power feeding" of reptiles is adding to the shortage. This means giving them two or more rodents a week, which encourages fast growth. "People are 'bulking up' their snakes and lizards. It's an image thing," says David Tetzlaff, an animal curator at Caribbean Gardens, a tourist attraction in Naples, Florida. "I've seen monitor lizards so overfed they look like footballs with legs." The sad truth is that small lizards and snakes just don't impress any more. The promotional slogan for the 1998 remake of Godzilla has embedded itself in the psyche of many a reptile fan: "Size does matter". James Murphy, a herpetologist at the National Zoological Park in Washington, DC, says that these days he can easily distinguish between pythons or boas that have been reared in captivity and those found in the wild. "The captive- bred ones have bodies so big that the heads can't keep up with them." Never mind the rodents: all this eating can mean an unhappy end for the reptiles. David Tetzlaff delivers a gory warning about the risk of "hair impaction", which afflicted one of his monitor lizards last year. Too many rat snacks, he says, caused the creature "to form a hairball the size of an orange in its gut. A vet had to perform emergency surgery."

Working at a breeding centre is, according to many, a revolting profession. "It's filthy - and then there's the smell," says Susan Tippie. Her worker turnover rate is almost 100 per cent a year: "Some people quit during their first coffee-break."

She is careful, she says, not to rear animals that are too ferocious, putting down "the biters" with gas - "because biters breed biters". She herself has been bitten a fair few times in her eight years in the rat- and-mouse business, and the leather gloves she wears to work show the wear-and-tear of daily nibbling.

Paradoxically, in the midst of this surge in demand, some rodent breeders still haven't made much profit. "I heard there's a fortune in rats, but I haven't seen it," says Jim Dykes. "I sold about $100,000-worth of prey mammals last year, but I'm living on noodle soup. In fact, the rats eat better than I do."

Many new breeders make critical mistakes, such as keeping the thermostats in their breeding buildings at too low a setting, which can mean that they wipe out much of their stock overnight. That is what happened to Jim Dykes. One night last spring he allowed the temperature in his mouse building to fall and remain for several hours below the 70F at which the creatures thrive. He had forgotten to turn off a huge fan that helps to cool the building during the day: mice and rats often stop breeding if the temperature exceeds 80F.

The result: "Most of them died and our production of mice dropped to 400 from 4,000 a week." The financial disaster was compounded because, to keep his regular customers happy, Jim Dykes was forced to buy mice at retail on the open market to meet his orders. "So I got stuck as a buyer in a seller's market," he shrugs. In addition, he is beleaguered by buyers striking a hard bargain. "They'll call you up and say, '40 cents for a mouse? I can get them for 25 in California.' But when I ask them why they don't buy them in California, they say their breeder doesn't have any. So I say, 'Well, if I didn't have any, they would be free.'"

Another factor that savages new and relatively small breeders (to be "big" in this industry you need to produce at least 20,000 critters a week) is that often they are unable to fill orders, which they need to do if they are to develop a loyal clientele. "Your big commercial customers don't want a few dozen; they order by the hundreds and thousands. If you delay on one order, they'll find somebody else," says Jim Dykes. "I know I can sell every rodent that I can get my hands on." So just in case the rodents don't keep up, he has recently multiplied his breeding stock by buying out a nearby company. This has not only doubled the size of his business, it has also reduced local rat-and-mouse competition.

But expenses run high. When rats or mice are crammed into tight living conditions, they sulk and squabble, so Jim Dykes recently spent $20,000 on several hundred solid metal pans that were manufactured to hold cat litter, but which he uses for housing his rats. Dykes limits each container to about four animals, and thinks that the increased calm and comfort will result in a faster breeding rate. He admits to an unlikely admiration for the rodents. "A rat is a very intelligent and gentle animal, compared to a hamster or gerbil: very laid-back. I try never to get attached to my rats because it would be harder to 'off' them."

About half of the prey mammals sold in America are gassed by breeders and sold frozen. Jim Dykes, for one, considers this more humane than selling them to be eaten alive. "I personally think that's so the reptile owners can watch it more than anything else. I don't know why they don't get bored, watching it over and over again."

Freezing rats and mice for 30 days kills any parasites they may be carrying, making them safer for reptile owners to handle, as well as for the scaly diners. So says Bill Brant, owner of Gourmet Rodent in Gainesville, Florida, one of America's biggest and best-known rodent farms. His customers include the most prestigious zoos and theme parks, including Walt Disney World. Brant represents the polished business aspect of the industry: Gourmet Rodent accepts American Express, and an illustrated website updates the number of its Internet customers - more than 11,000 at the last count.

Brant takes a methodical approach. His bible, he says, is a novel about the manufacturing industry called The Goal, written by an Israeli physicist-turned-management guru whose name is, of all things, Eli Goldratt. Brant c ites Goldratt's formula: "He explains that you have to understand the nuts and bolts of production, inventory and distribution. The most essential is maintaining stock. We're manufacturing rats and mice, and we have to be ready for surges in demand. That's my real concern, as it should be for every astute rodent breeder."

Nice theory - but nature does impose limits on human management expertise. The gestation period for a typical mouse or rat is 28 days for a litter of three. They can bear almost continually between the ages of five months and one year on average. After that, fertility declines. Males begin mating at roughly six months, and do so effectively at a rate of about 20 times per day. Males usually stud for up to three years. After that their sperm count drops sharply.

Brant's market focus is national, and mainly to institutions and collectors rather than to traditional pet owners who are nurturing perhaps a single snake. "It's easier to sell 1,000 rats than 10," he says. He is concerned that some zoos and theme parks are starting to breed their own prey mammals, but he thinks they'll soon become disenchanted with that approach. "They'll find that management of a rodent colony is hard. It's easier to breed pythons and monitor lizards than all the rats and mice you need to feed them."

The ease with which reptiles can be bred is the main cause of the increase in demand for rodents, says James Murphy. "When I got into this business 20 years ago, it was rare for snakes to breed in captivity. It was all we could do to keep them alive. Most are very delicate, and there wasn't enough research to know what conditions they needed." Today, though, numerous breeders' shows feature serpents and lizards in customised colours from hot pink to bright orange. Murphy grins: "I never dreamed of seeing exotic reptiles on a production line."

Rodent breeders simply can't keep pace. Many mice and rats which are kept to maturity as breeders begin to grow tumours in early adulthood. "You have to wonder about all the cancer research based on mice getting tumours," muses Jim Dykes. "Seems like nothing more than air and water and grain cause tumours in my mice, because that's all they're exposed to."

That's as may be, but Susan Tippie has darker suspicions regarding a spate of recent overnight deaths among her stock. "I can't prove it, but I think some competitor is responsible. I could smell poison near the dead animals' cages." She adds, with a smile: "I smell a rat."

Robert Johnson is a staff writer for the 'Wall Street Journal'