Trekking in the Himalayas; Stones of Silence, by George B. Schaller. New York: Bantam Books. 292 pp. $3. 95.

In this fascinating book, Schaller, one of the world's leading animal biologists, tells of his six years trekking in the Himalayas, observing and recording the region's wildlife. But his conclusions aren't what you might expect. Schaller says indiscriminate hunting and destruction of natural habitats threatens to wipe out much of the mountain wildlife.

With scientific precision, he describes such wildlife as a herd of Himalayan tahr (an animal so exactly between goats and sheep that it's put in a genus of its own).

It's a mixture of brass-tacks biology and the author's sense of adventure, beauty, and discovery that makes this book a worthwhile read. Schaller makes you feel as though you're hiking with him, hearing his thoughts and observations along the way.