A pleasant addition to the series inaugurated by Victor B. Scheffer's The Year of the Whale (1969) and The Year of the Seal (1970). If the name ""koala"" means nothing to you but cuddly adorability, the fortunes and misfortunes of Williamson's ""Talgara"" and ""Boorana"" will be a startling education. The little marsupials represent an evolutionary bypath adapted to a few specialized circumstances: arboreal existence, scarce water (their eucalpytus4eaf diet provides enough), almost natural enemies. The pitiful limitations of these circumstances can be appreciated from the structure of the koala's great, powerful, dangerous claws--which grip in only one direction and are useless for the head-down climbing which would infinitely simplify the animal's existence. Outside of its own environment, the koala's self-protective instincts do not function reliably. Inevitably, its habitats are being surrounded and cut off by increasing human settlement; unlike deer or foxes, it lacks enough inborn recognition of danger to make itself scarce in exposed territory. The few eucalyptus enclaves that remain in New South Wales will support only limited koala populations--if the animals do not destroy all the surviving growth in overcrowded groves. In this case, the end of Eden comes in the form of a fire that destroys the comfortable community in a secluded gully where tough old Boorana is king of the walk and placid Talgara is carrying a helpless cub in her pouch. Hindered as much as helped by occasional human assistance, they make their separate, chancy ways to new surroundings. The month-by-month format is nicely managed despite the huge amount of information that must be worked in; Williamson's attitude effectively subordinates sentimentality to sympathetic detachment.