THE GROUSE DISEASE INQUIRY.
THE Interim Report of the Committee appointed by the Board of Agriculture to inquire into the causes of grouse disease is in more than one way a curiously interesting document. It is published at a time of year when the thoughts of a large number of persons are con- centrated on a favourite form of outdoor sport ; but apart froM the probabilities of the present season turning out a goOd or bad year for grouse shooting, the Report has an economic importance. It is the result of an inquiry instituted by the Board of Agriculture of three years ago, when Lord Onslow was Minister of Agriculture. During the past half century grouse shooting and the management of. moors and forests have gradually increased their sources oC .providing employment until the stability of that employment has become a serious matter, and any cause which tends to diminish it might well form the subject of investigation. It is not, of course, merely a question of supplying more or less sport for persons who can afford to pay for it; that would be relatively a small matter. But it would not be questioned that for large numbers of visitors and residents to spend their holidays in Scotland (or, as some still hope, in Ireland) instead of abroad may be productive of considerable local prosperity. That is one aspect of what may appear at first sight a matter which concerns sportsmen only. Another interesting point is the characteristically British method of inquiry. It' is admitted that the subject is one of importance to thousands of persons, but the President of the Board of Agriculture rightly decides that since it is only a section of the .community which is interested, there can be no support given to the movement from public funds. In no way deterred by the refusal, the Committee set to work to organise their inquiry on a purely voluntary basis ; funds are collected, agents appointed, field observers selected for their acumen and experience, and the Committee sit down for two and a half years' arduous labour in collecting statistics and sifting evidence. They have now issued an Interim Report, stating at the same time that the funds originally guaranteed are nearly exhausted, and that it will be necessary to appeal for further subscriptions to enable them to complete their inquiry and draw full con- clusions from their work.
'Viewed scientifically, the problem they set out to solve was diffiOult and absorbing. The origin and cause of the epidemic, vaguely described as grouse disease, have hitherto baffled investigation. It has become generally accepted, and the researches in the past by Dr. Klein have been admitted in evidence, that there are two forms of grouse disease: one, which the Committee guardedly denominate as chronic, the other, a form which Dr. Klein described as acute. The symptoms of the first form are loss of weight, congestion of the intestines, and irregular moulting, resulting often in bare legs and dingy plumage. The signs of the other form are said to be different. The bird is stated to die suddenly in full weight-and'plumage. Dr. Klein regarded it as an acute infectious pneumonia, caused by a bacillus probably belonging to the " colon" group, which was found post mortent iu the lungs- and other organs of the infected bird. That is, roughly, the position in which Dr. Klein left the investigation. The question is whether he was right, and whether there are two forms, or only one, of the epidemic. Obviously the Committee cannot commit themselves to an opinion at this stage. But it is not difficult to guess the lines on which they may be supposed to believe they are working to a definite conclusion. They have attached the greatest importance from the first to bacteriological investigation. Their experts, during the seasons 1905, 1906, and 1907, have examined in the laboratory, or actually on the moors, over eight hundred birds suffering from the chronic form of the disease, and these birds have been examined minutes, hours, and days after death. In every case the bird has been found to be suffering from the chronic wasting disease. During the three seasons the Committee has not come 'across a single instance of the acute pneumonic form of disease described by Klein. Keepers, nearly all of whom have hitherto been convinced believers in the theory that there are two grouse diseases, have reported instances of the sudden pneumonic form, and have forwarded bodies of grouse said to be of full weight which have died of it. In every case it has been found that the bird was suffer- ing from the wasting disease, or died as the result of an accident. More, for it has been proved that the particular bacillus which Klein isolated from the birds he believed died of the pneumonic form of disease can be isolated from the organs of both healthy and emaciated birds. The Committee do not discredit Klein or the evidence of keepers generally, but they draw attention to these facts ; for the conclusion, we must wait for their final Report.
Meanwhile the Interim Report declares that inquiry has established at least one fact. The main controlling condi- tion of health and disease is the supply of food. The chief food of the grouse is the young shoots of the ling, or calluna vulgaris, whose tall branches of pink flowers seta distinctive note of colour beside the deeper purple-rods of the bell-heather. The years when the birds cannot get a good supply of young heather coincide with the years when disease is virulent, and, of course, a contingent factor of the problem of demand and supply is the proportion of birds to the acreage of moorland. There is a recognised period in the fluctuations of the numbers of grouse. Going over a cycle of sixty years back, the cycle will be found to comprise the good year, the very good year, the record year, the bad disease year, the recovery, the average, and the good average. The round is almost invariable, though there may be exceptions on different estates to prove the rule. A bad year may be followed by a year of disease. But there may be cogent reasons eveu for the exception. It would not follow, because the proportion of birds per acre on one moor greatly exceeded the proportion per acre on another, that therefore the more crowded moor would necessarily be more liable to disease. It might carry a far more abundant supply of food. A large moor, with few birds and an insufficient amount of young heather, would be liable to disease where a small moor, well stocked and well supplied with food, would escape.
Hitherto, then, the investigations of a Committee which deserves the gratitude of men of science and students of biology as well as naturalists and sportsmen, appear tO have resulted rather in the emphasis of a law than in the discovery of a secret. The bacteria which kill grouse in the years when disease is rife are also in existence in years when no grouse die of disease. The constitution of the bird is strong enough to throw off their attacks when it can get plenty of good food ; as soon as the food supply fails, the bird weakens, the bacilli flourish,' the bird dies. It may be that further investigation will deter- mine which of the various foods which the grouse swallows is the " host " of the destroying bacillus, though, even if that fact were established, it is difficult to say in what way the grouse could be protected against it. Conceivably it might be demonstrated that the presence of the bacillus is even necessary to the health of the bird, and only kills it when Nature has decided that the individual should die for the good of the race. On some such principle, it may be, it will be discovered that the guiding and binding laws of all growth of population depend, whether of birds or beasts or men. Meanwhile those who are content with all forms of outdoor sport in proportion to the naturalness and wildness of their conditions may be allowed to hope that grouse shooting, even if attended by scientific study, will still remain unspoiled by artificial aids. It may be well to see that, so far as it can be guarded against, there shall be no predisposing cause for disease among the wild birds on a moor. But it is not to be expected, nor to be hoped, that human control over wild life will ever be perfect or even easily directed. When man steps in to alter the balance of wild life he can never tell what steps Nature will take after him to have her own way in the end. She will return, however costly and however scientific the pitchfork by which she is expelled.
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