The Kingdom of Claptrap : NATIVE TONGUE, <i> By Carl Hiaasen (Alfred A. Knopf: $21; 325 pp.)</i>

Apparently, there are only two blue-tongued mango voles (rat-like members of the rodent family) left on the face of the earth, and in the opening pages of “Native Tongue” one of them is unceremoniously heaved out the window of a speeding blue pickup truck on a highway running between the mainland and the Florida Keys. It lands on a pair of terrified children in the back seat of a rented convertible and, moments later, is assassinated by an obliging highway-patrol officer, who doesn’t want the kids’ Florida vacation to get off to a bad start.

This seems to pretty much spell doom for the species, not that there was much hope to begin with. The fact is, the voles were having trouble procreating; the zoologist in charge of them at the Amazing Kingdom of Thrills theme park in North Key Largo had reluctantly concluded that the last female blue-tongued mango vole in the entire world might, in fact, be a lesbian.

Welcome to the gassy, hyperbolic world of Carl Hiaasen, who, if he weren’t such an original, might be termed a South Florida hybrid of Jonathan Swift, Randy Newman and Elmore Leonard. In “Native Tongue,” his fourth thriller, the mango vole tragedy is, of course, merely the tip of a large and eccentric iceberg, involving the Amazing Kingdom itself, the adjacent oceanfront mangrove that is about to be bulldozed to build a golf club, a Gray Panther-type gang of animal activists, a hermetic ex-governor of the state, a local phone-sex line and even, at a distance, John Lennon’s assassin and New York mob boss John Gotti’s closest associates.

Driving his story at a hair-raising tempo, Hiaasen is that rarest of things, a comedian whose sense of moral outrage really stings. In “Native Tongue” he is after his usual quarry: those who gleefully rape and pillage the Florida wilderness with a blood-lust not entirely explained by simple venality. He’s a dead-eye shot.

The novel’s hero, Joe Winder, is an ex-newspaperman with a bad temper (Hiaasen currently is a columnist for the Miami Herald, and knows the news business inside out). Joe takes a job as a PR flack for the Amazing Kingdom (South Florida’s pathetic answer to Disneyland), more or less out of desperation, and the job figures to be a no-brainer. But the mango vole tragedy presents just enough unanswered questions to stir the dormant reporter’s instinct in Joe, especially when the zoologist in charge disappears and Joe himself is assaulted by a gray-haired old lady laying claim to the burglary on behalf of something called the Mothers of Wilderness. Joe smells an actual story, and, needless to say, by the time it gets told it’s a whopper.

The details will not be revealed here, but Hiaasen packs enough of them--lurid, inventive, improbable--into 325 pages to leave readers dazzled, and more than a little exhausted by the sheer number of acts described--violent acts, sexual acts, even animal acts. If there’s fault to be found with his method it is that he’s a compulsive entertainer who can hardly resist trying to top himself in page after page. Amazingly enough, he almost always succeeds.

He is also, by now, settling into a plotting formula (and a few welcome appearances from recurring characters), but it’s hard to name a thriller writer who isn’t. Hiaasen’s heroes tend to be burnt-out newspapermen with a past, and while each novel has attacked a different segment of the Florida economy (tourism, professional bass fishing, plastic surgery and now theme parks), the ultimate enemy is always the same: overdevelopment of the last remaining wilderness in the state.

Is this sameness an especially bad thing? Not really. Hiaasen’s love for what Florida might be is as strong as his indictment of the shysters, boobs and sleazebags who have turned it into a kingdom of claptrap. As a result, his novels are shot through with a kind of real passion that lurks beneath the manic pose--an urgent affection for his subject. Nor is there anything self-righteous about his characters or his attitude. The good guys in “Native Tongue” are morally ambiguous, irresponsibly resourceful, and almost as temperamentally unpredictable as the most colorful of its villains, a security guard named Pedro Luz, who is so addicted to anabolic steroids that he moves around the Amazing Kingdom pushing a rolling IV rig at his side, alternately sucking on the tube and plunging it into his muscles.

Like the steroids, Hiaasen’s prose creates buzzing head-rushes and disorienting spasms of muscular joy that leave one feeling refreshed, if not exactly cleansed. Lets hope his book doesn’t cause cancer. In every other way, it’s a killer.