Roger Caras is a television reporter on nature, the environment and animals. He writes a pets column for Ladies' Home Journal, is a vet-school lecturer on animal biology and a Fellow of the Royal Society, London. Over the years he has kept a critical watch on cruelty -- in sport hunting, rodeos, farming, and has written more than 40 books. New this year is "The Forest," and reissued after a decade of being out of print, "The Custer Wolf," a book of which Gerald Durell says in his introduction that in a lifetime of reading about animals he "can count on the fingers of one hand the number that have been as well written and so delicately observed."

"The Forest" is perhaps even better written, more disciplined, its moralizings confined to an afterword in which the author expresses his sense of foreboding on behalf of forests.

What happens in the northwestern coniferous forest of this book is expressed in the marvelously complex webs of life that permeate and surround a singly giant hemlock, On a branch overlooking the forest canopy a female golden eagle perches, waiting till hunger or an urge to play the thermals launches her again. The time span is the three weeks of this transient's visit.

Caras sketches in the residents of the forest -- lichens and bark lices, tree mice in their needle nests wealtherproofed with spider webs and feath ers -- a cast of thousandds, all interdependent in the obvious way of a food chain and in other ways that are surprising. Like the tree itself, all hold critical chemicals in storage and convert others. In the mash between the tree's roothairs amoeba basses "slimy sausage" -- mmove along like slugs. Alongside the tree, white pine butterflies, "living dust of the forests," ascend the spirals and drafts. High up, a piney sprite and a pine marten rip through the top branches in a high-speed chase.

Encounters here lead to quick disappearances into jaws, gullets or pools of digestive juices. Stringling earthworms make a meal for the mole which then feeds the chittering shrew, itself soon food for a rattler which in turn is taken, head on, by a snade or superior craft and patience. One wipe of a paw lands the whole as semblage on the forest floor where the black bear rolls in the mess, eats a little and ambles away. A littermate to the late shrew arrives to nibble on what's left. Enter the brash raven, hungry, too. And so on.

As it pleases him, Caras slips in instruction -- on animal signs, signals, airborne social gestures (the scents which do not tempt or taunt but command) or on the antlers of an elk. He has seen in the wild all the animals except the fisher (a weasel) and the mountain lion. No human being appejrs in the book. The reader is aware only of a knowledgeable observer with fine-tuned sensibilities, a heart quick to marvel and a good gauge of the nonscientist's span of attention.

In recent years the wolf has been enjoying a better press. Newcomers to "The Custer Wolf" (1966) will be prepared for the good-guy treatment in this reissue. The first two-thirds of the book, based on the author's study of a wolf pack in captivity, describes the idealized life story of a wolf family in South Dakota between 1910 and 1920 as a litter of five cubs is trained in the ways of the predator. The final third is based on history: The war on wolves took place; a Custer Wolf existed. He was white and a renegade, terrorizing Custer, S.D., with his wanton kills, taunting hunters and their dogs, evading lures, traps, poisoned fat pellets, and baited carcasses on a six-year rampage across six counties. You could read about him by name in the Yearbook of the U.S. Department of Agriculture for 1920. He was killed by a hunter who painted the bottoms of his boots with fresh she-wolf scent.

This book has an intensity and flow that make it special, a lyric quality to its depiction of the wolf's world of keen senses and passion for survival. Caras can be faulted for excesses of language but never for anthropomorphism. He says he struggled against sentimentality; it seems right that he didn't wipe it out.