Cuddly Killers : The author of ‘The Secret Life of Dogs’ turns her attention to the felines : THE TRIBE OF TIGER: Cats and Their Culture, <i> By Elizabeth Marshall Thomas (Simon & Schuster: $20; 240 pp.)</i>

“Observation is a useful tool . . . for all the cats,” writes Elizabeth Marshall Thomas, an avid observer herself. For decades she has been watching wild cats and captive cats, the tabby no less than the lion. Following hard on the heels of her fascinating canine expose, “The Hidden Life of Dogs,” Thomas’s latest book, “The Tribe of Tiger,” describes what the felines have allowed her to see of their haunts and their habits, despite the fact that “to be unseen and undetectable is a state that seems to suit the cat family.”

As keenly as the author has used her eyes, she uses her heart, expanding sight into a lucid insight that guides us deep into cat country--a hair’s breadth from the warm crouching beast.

Common knowledge has long held cats to be inscrutable. Tell a dog what to do, and he’ll most usually do it. But don’t bother even asking a cat, who is busy with an inexplicable, independent agenda. Thomas, however, has found the key to the delightful puzzle: The feline raison d’etre is the pursuit of prey.

“The story of cats is a story of meat,” she explains, and goes on to note that “hunting preoccupies a cat almost from birth.” The 35 species of cat, which range most corners of the earth, have evolved into precise, efficient killers. Some are stealth hunters, others are group hunters, and still others, like the lightning-quick cheetah, are coursers, who run down their prey. Don’t look askance at pudgy Mittens, drowsing in the noontime sun on your living-room rug. One of Thomas’s own house cats, Rajah, neatly slaughtered a loaf of Italian bread, first clutching the sides with razor-sharp claws and then finishing it off by biting deeply into what would have been the neck if only the bread had been built more like the mouse or wildebeest of the cat’s active imagination.

Indeed all cats, big and small, are excellently outfitted for killing. A short list of features includes sensitive, mobile whiskers; long eyeteeth for latching onto prey and triangular cheek teeth for tearing flesh; claws; acute eyesight; a complex sense of smell; and scent glands used to leave friendly messages for family members or to warn strangers away from protected territory. All this is housed in a body of superb strength.

While predation certainly defines feline biology, it may also explain feline emotions. “Many expressions of a cat’s feelings,” Thomas states, “seem deeply related to the capture of live prey. An excited, happy, or much relieved cat may ambush and pounce upon whatever triggers its pleasure--something worth considering before getting a large cat all worked up.” And no one can mistake the actions of a cat at play, mimicking methods of pursuit and attack just for the heck of it. (As I am writing this, sturdy Alonzo, white whiskers blazing above his classic tuxedo markings, has decided to pass the time by doing in a pair of defenseless sunglasses.)

A perusal of “The Tribe of Tiger” will teach you all this and more: how cats communicate with one another, how they establish territories and social groups, why they fight, and how they love. Thomas supports her material with relevant literature, yet throughout her book she speaks less in the voice of the scientist than in that of the storyteller. We hear of the lioness, shot unnecessarily, whose companion sat with her as she died, “turning her fur the wrong way” with a gentle grooming tongue. And unforgettable Ruby, the domesticated puma, capable of “singing the murderous song of a cat’s dark feelings, a contralto solo of envy and displeasure.”

Simple and non-judgmental, Thomas’s musical prose tells tale after tale of the cat, revealing these creatures in all their integrity, in all their danger, in all their splendor. The latter two sections of the book turn from paean to lament: Once upon a time humans and cats could live and hunt side by side. They kept a truce based on mutual needs and mutual respect. Since then, we have let down our end of the bargain--eroding balanced habitats, trafficking in hides and bones, butchering big cats for money and sport.

“We are surely the primary agent of death for all members of the cat tribe,” says Thomas. “For many if not most cat species, our depredations must surpass accidents, disease, and even starvation by a considerable margin.” The damage having been done over decades, now we are scrambling to redress our sins. Funds are raised for managed game parks, captive breeding programs, study after study on species slowly succumbing to extinction. What have we done to that “deep and perfect wilderness,” where humans existed peaceably with the cats? Eden, once lost, is irrecoverable.

In “The Tribe of Tiger” Thomas openly mourns for the world’s wild cats, as only someone who has lived among them can mourn. Most readers, having encountered lions and tigers only through the bars of a zoo enclosure, will be limited to comprehending the dilemma by means of intellectual empathy. Yet those of us who have invited some of the smaller cats into our homes may come close to touching the depths of Thomas’s feelings. In the recording, “Songs of the Cat,” Garrison Keillor bids good-bye to his feline companion like this: “He was good company, / And we miss his gift / Of cat affection while he lived, / The sweet nature / Of that shy creature / Who gave the pleasure of himself.”