NATURE NOTES

Evening Post, Volume CXXIX, Issue 105, 4 May 1940, Page 9

NATURE NOTES

GOOD OR BAD?

THE INTRODUCED OPOSSUM'

(By R. H. D. Sti^olph.)

■ -Fears for the future of native bird life in the Charleston district, nesr . Westport, are expressed by Mr. J. Morris, a resident of that area, on account of an increase in the numbers of the opossum. This animal he regards as the greatest pest ever : imported into New Zealand. If, in consequence of economic conditions, no trapping is done in district's where opossums are now numerous, as, for example, the district in which" he resides, he states that it appears to him that, in five years' time the native birds will be wiped out. During the'1 last three years, he points out, there has been little trapping in his district and. opossums are now everywhere, while birds are becoming scarce rapidly. Today, he asserts, there is not more than one-tenth the number of native birds in his district than was the case three years ago. Seldom this past season has he seen any young birds about, excepting the sparrow, though a few years ago hundreds would be seen. In support of his fears, Mr. Morris goes on to state why he believes the native bird life will be " injuriously affected by the opossum. . THREAT TO BIRD LIFE. "In the near future, if the opossum is not heavily trapped, there will be no native bush birds left," he writes, "and probably our forests will be feeding millions of opossums in their ■ stead. What a tragedy is near at hand. Will anything be done about it? For more than twenty years past I have never known a bird which had built its nest in a tree inhabited ' by an opossum to hatch young birds and during that period I have seen many birds' nests. I know for a positive fact, for I have witnessed it many times, that birds' are driven from their roosting places by the opossum during the night It stands to reason that the opossum, as it is such v an active little animal, jumping from tree to tree at a great rate and travelling over a vasts area during the night —and considering the numbers of them at large—must greatly disturb the bird life. Many birds are frightened from their nests with a ten or fifteen pound opossum suddenly thumping near the nest. I think most people "will know the result. I have read of an opossum eating birds' eggs." There seems to be little doubt, if the opossum becomes too numerous, that it would cause damage to our bird life, and it is imperative that its numbers should be kept in check. ' ; DIET OF OPOSSUM. It is as well to bear in mind, al- ' though the opossum may occasionally vary its diet with the flesh of a bird or with birds' eggs, it is essentially an _eater of leaves. Some indication of its good in New, Zealand was* published by the' late Hon. G. M. Thomson • in his volume on '.'Wild Life in NewZealand," in which he quoted the observations of Mr. F. Hunt, of Round Hill. "The food the opossum lives on," wrote Mr.-Hunt, "is chiefly leaves ' of broadleaf, kamahi, , broad-gum (Panax), and mapau (Pittosporum), rata-blossoms, supplejack-bsrries, b9"= ries of fuchsia, and makomako and practically all the: seeds and blossoms that grow in this part of the bush. The opossum is not a grass-eating animal. It will eat white or red clover, sweetbrier shoots, and seeds, but if an opossum is. caged and fed on grass it will doe of starvation. Also, if it were fed on turnips, it would take as much to feed twelve opossums as one sheep would eat. When I and my brother were catching opossums for the Southland Acclimatisation Society," Mr, Hunt continues, "we fed them on carrots, boiled wheat, bread, boiled tea. leaves with sugar, and anything sweet. The damage the opossums would da running at large would be very little, seeing that, they never come on to open country. The animal is blamed for barking apple trees, but the opos* sum does hot bark a tree. It might scratch the bark with its teeth, but it does not strip it off." WELL ESTABLISHED. Mr. Thomson went on to give the (testimony of Colonel Boscawen, of Auckland, who, he stated, was a most ' - reliable authority, to w the effect that as long as there was plenty of green stuff available opossums did not interfere with fruit but that the damage they were often charged with was the work of rats—presumably black rats. Mr. Thomson mentioned, however, that at several places • which he named, besides others, opossums were stated to be destructive in orchards, eating the shoots of apple and plum trees in the springtime and the fruit in the autumn. In any case, one thing is quite plain. The opossum is now common in many parts of the country and contrary to a general belief that it is more or less confined to forest areas, that is not the case. At the present time, the opossum is widely spread, even in well-settled districts, including populous towns. The writer knows of an instance recorded recently in! which a gardener had the ends of his roses eaten by opossums. Traps were set and in a short period five opossums were caught, and his garden was in the centre of a town of some thousands of inhabitants! A fringe of- native bush within a mile of the Post Office, - -when systematically trapped, yielded a hundred opossums. It can be seen from these instances how firmly the opossum is now .established in New Zealand. NATURAL BALANCE UPSET. Although instances are on record in which an animal which is introduced to another country is liable to become a nuisance, it is as well to remember that in. Australia and Tasmania the opossum is not regarded as an enemy to bird-life. Australia is known as a land of birds and it possesses as great a wealth of bird-life as almost any other country in the world. The so-called opossum—the real opossum is a carnivorous animal which is -not found in Australia—is quite common in various parts of the Commonwealth : and appears to live on good terms with the feathered inhabitants of the bush. This happy position is due no doubt to the balance that has been maintain- v ed by the iron rules of Nature, which prevent any undue increase in tha numbers of the opossum to the detriment of other wildlife. In New Zealand, these natural enemies of the opossum are absent and there, is ' a , possibility, unless the numbers of this animal are kept within bounds by j systematic trapping, that it may become over-plentiful and cause destruction of bird-life in' the way indicated by the correspondent at Charleston. Moreover, certain ground-frequenting birds, such as the kiwi-, suffer severely by being caught in opossum traps.' Th« losses in this way are serious and even without taking • account of th» birds which may be? destroyed by the opossum in other ways, the threat to • ground-frequenting birds, which includes the most interesting species that I New Zealand possesses, is a real and (growing one. r.