ORIGINALLY published in 1980 when its author was 86, To Whom the Wilderness Speaks (Natural Heritage, 192 pages, $14,95 paper) is a book that cannot die so long as there are readers for whom understanding and protecting the natural environment is a priority. Nearly 50 years ago, Louise de Kiriline Lawrence and her husband Len built "a small loghouse in an uninhabited forest" in Northern Ontario, intending to "live the simple life." What happened instead was Louise's wholehearted involvement in surroundings that were anything but "uninhabited." This book describes that involvement, in a collection of nature stories recounting intimate details in the lives of whippoorwills, chickadees, jays, phoebes, hawks, squirrels, and deer. Make no mistake, this is one dedicated observer. "Never again during the next 30 years was there to be a similar coincidence," she writes, and no one who reads To Whom the Wilderness Speaks with half the care that went into writing it will doubt her. The book's style is a match for its substance, and so are the delicate and precise drawings by Aleta Karstad.

THIS IS no ordinary bird book; The Nature of Birds(Firefly, 160 pages, $19.95 paper) contains no species lists, sketch maps of habitats, or notes on identification. Yet it could prove as valuable as any field guide. Adrian Forsyth has a Ph.D. from Harvard and a homestead in Ontario. He also frequents Costa Rica, practising what he preaches in The Nature of Birds: "Ecologists and ornithologists cannot do credible research if .they study only half the life history of an organism." An estimated "five billion birds, at least 248 species in all," leave North America to winter in the tropics, where their habitats are fast disappearing. Each year, fewer return. If North American ornithologists don't get actively involved in conservation soon, says Forsyth, there'll be nothing left for them to study.

He also urges amateur birders to expand their activities at home and abroad, because professional science urgently needs their contributions. Reading this book, which uses breathtakingly beautiful photographs to underline creative observations on such topics as plumage, infanticide, and intelligence, is an exciting place to start.