TILE KOALA IS SLIPPING
By HUGH NICOL
NOT, of course, down its tree: koalas are much too good at climbing for that ever to happen. Koalas— those fascinating originals of the teddy-bear—are slipping away from life ; their numbers have been reduced to some- thing very close to the danger-point, and they may perish in spite of all that is now being done to save them. Not very long ago, koala pelts were being exported in millions. The koala has already become extinct in South Australia. It never existed in historical times in Western Australia. In Queensland and in New South Wales, its numbers have become almost vanishingly small, and the hundred or so of animals that are supposed to form the total koala popu- lation of the former State are riddled with disease and are faced with an acute shortage of food. Only in Victoria does there seem to be a chance to preserve the koala race, and even there, only about a thousand were thought to be living before the recent extensive bush fires.
The Australian conscience has been aroused, and the koala is now granted nation-wide protection by law, and— more important still—by public sentiment. Nobody would willingly harm a koala, except perhaps by mistaken kindness, but even that is forbidden, and legal permission has to be obtained before anyone may keep a koala as a pet. Such permission is seldom granted. The koala has no natural enemies amongst the native Australian animals, though introduced animals, such as dogs, kill a few koalas that have left their food-trees and are migrating in search of new ones.
The problem of maintaining the koala is solely one of diet. Koalas live exclusively on eucalyptus leaves and parts of the bark of the finer branches. They do not drink. (The word koala is an aboriginal one meaning " does not drink," and should be pronounced as three equal syllables: ko-ah-la.) As Australia is popularly supposed to be plenti- fully stocked with eucalyptus, the problem may seem simple to solve. Actually, in perplexities and in scope for systematic deduction it rivals problems propounded by Mr. J. J. Connington and other experts in scientific crime-fiction.
With the best will in the world, those people who sought to preserve koala " bears " in Australian zoos poisoned them all. None lived more than three or four years in captivity ; most died after a few months or a year. The bears were given eucalyptus leaves and young branches, sometimes taken from the very trees on which koalas in the wild had been seen to live and flourish. Painstakingly, leaves and branches were gathered from the favourite eucalyptus species of the koala race ; the animals were given a choice of food from several sorts of tree at once. Nothing availed ; the animals all died, and at last Mr. Ambrose Pratt thought that the koalas had died of prussic-acid poisoning. He consulted some scientists, who laughed his idea to scorn: how could the captive bears have been given prussic acid?
Finally, Mr. Pratt found one scientist less hide-bound than the rest, and this man said, yes, he had heard that one of the eucalypts (the so-called sugar gum) contained prussic acid. This tree, however, was seldom used as food by koalas. Was it possible (Mr. Pratt asked) that other eucalyptus contained prussic acid, too? The chemist did not know ; nobody seemed to know ; but it was possible. Further enquiries were made, and it was found that not only the sugar gum, but the manna gum (another eucalypt, and one of the favourite food trees of koalas) was known to be a bearer of prussic acid. In the case of the manna gum, the leaves of suckers and young shoots were especially poisonous. The poor koalas in the zoos had been given these in quantity, and, having no other food to turn to, had eaten them, and died.
Observation has shown that koalas in the wild avoid the young shoots of the manna gum. A group of bears may live for several seasons in one manna gum tree, or for part of a year, and then they suddenly forsake it and migrate— possibly for miles—past other trees apparently identical with the one they have forsaken, until they come to one in which they settle. If driven by hunger, adult bears will eat the poisonous leaves of young trees ; sixty died in one night in one place after a bush fire had destroyed the old trees and had left only an aftergrowth of fresh shoots. Baby koalas, however, will starve to death rather than eat dangerously.
Instinct evidently plays a great part in determining what koalas eat. They can distinguish between different sub- varieties of eucalyptus trees better than even a trained Australian botanist can. It has recently been found that apparently identical trees growing a few yards apart differ considerably in the composition of the oils contained in their leaves. Chemistry, in fact, and not botany, provides the crux in distinguishing one eucalyptus tree from another, so far as humans are concerned ; but the koala, having no laboratory, has learned to distinguish good leaves from bad, and to know whether a tree that has yielded good food for a season has suddenly changed its make-up and become poisonous. Nowhere else in the world, it seems, do trees of one species vary from spot to spot and from time to time in the way these Australian eucalypts do.
The koala in its native state could cope with these peculiarities of the Australian bush, but now that settle- ment by white population has brought about extensive clearings, bush-fires, and other methods of reducing the area occupied by suitable koala food-trees, it becomes increasingly difficult for the few remaining koalas to find suitable trees devoid of poison.
The problem does not wholly centre around prussic acid. The attractiveness of the koala is largely due to its appear- ance and its freedom from vicious habits, but it has other qualities depending on its peculiar food. Well-wishers of the happy-looking and harmless koala are making deter- mined efforts to preserve this amiable race from complete extinction, and a number of scientists are engaged in finding out as much as possible about the composition of the eucalyptus trees. One of these men is working in London.
Mi. Ambrose Pratt has written a book entitled The Call of the Koala, and all proceeds from the sale of this book will be devoted to research on the koala and the trees on which it feeds. There is perhaps a moral, in these efforts, for us who have no koala bears but are countrymen of a large number of under-nourished children. We can at least wish success to those who wish to preserve the koala, and hope that they will not be too late.
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