SAVING THE ANIMALS: The World Wildlife Fund Book of Conservation, by Bernard Stonehouse (Macmillan, $21.95). Stonehouse, a Yale ecologist, here surveys 20 animal species threatened by extinction: among them, the leopards of the African savanna, the giant pandas of China's forests, the Galapagos fur seals, the Amazon jungle's tiny green frogs. There are some grounds for encouragement in their survival, concludes Stonehouse, but the fight to preserve them and their natural habitats must be unending. His book is illustrated by more than l00 photographs of threatened creatures by some of the world's finest nature photographers. A portion of the book's sale price supports the work of the World Wildlife Federation.

THE ART OF ROBERT BATEMAN, text by Ramsay Derry with an introduction by Roger Tory Peterson (Viking, $40). Robert Bateman is Canada's distinguished wildlife painter whose detailed canvases of birds established his worldwide reputation. One of his paintings was a wedding gift from the Canadian government to Prince Charles and Lady Diana. To the inexpert eye he seems an Andrew Wyeth loose in the forest primeval. The 82 color reproductions in this collection are stunning.

MULE AND BLACK-TAILED DEER OF NORTH AMERICA: A Wildlife Management Institute Book, edited by Olof C. Wallmo (University of Nebraska Press, $29.95). Mule and black-tailed deer live in the western United States, white-tailed deer live in the East. The 16 experts who contribute to this encyclopedic book reveal all about the western species, including its diseases and nutritional habits.

THE OXFORD ENCYCLOPEDIA OF TREES OF THE WORLD, edited by Bayard Hora (Oxford, $24.95). An authoritative work of reference prepared by an international team of 39 authors, this book describes 149 genera and over 900 species. An index cross- references 1,400 common and 2,200 scientific names. With 280 photographs, many in color, this is a good starter book for a person who aspires to be an amateur arborist. For instance, have you been recently puzzled by those green grapefruit-like objects in Georgetown's Montrose Park? They are in fact the inedible "false fruit" of the Osage Orange tree, whose wood was once used by North American Indians for making bows--hence the tree's other popular name, Bow Wood.