.;, FOR THE PEOPLE FOR EDVCATION FOR SCIENCE LIBRARY Of THE AMERICAN MUSEUM OF NATURAL HISTORY Frontispiece. ( P.Z.S. 1910. P/. Z.VAT///. ) Andre & blcit^li, Lid. PAIR OF RED GROUSE IN SUMMER WITH YOUNG CHICKS. THE GROUSE IN HEALTH AND IN DISEASE i- BEING THE FINAL REPORT OF THE COMMITTEE OF INOUIRY ON GROUSE DISEASE VOLUME 1 iriTJ{ 59 FULL PAGE PLATES, MOSTLY IN COLOUR AND 31 ILLUSTRATIONS IN THE TEXT LONDON SMITH, ELDER & CO., 15 WATERLOO PLACE 191 1 [All rights reserved'] //. '^^J, 0»Hi-C H"-^^ DEDICATED B7 GRACIOUS PERMISSION TO Ibie flDajest^ tbe Ikino. TABLE OF CONTENTS VOLUME I. CHAl'TBIl TJiOK Introduction. — By Lord Lovat xi Part I.— THE NORMAL GROUSE. I.— The Systematic Position of the Grouse. By A. H. Evans .... 1 II.— The Life History of the Grouse. By A. S. Leslie 5 III.— The Changes of Plumage in the Red Grouse in Health and in Disease. By Edward A. Wilson 29 Part I. — Plumage Changes in the Cock. Part II.— Plumage Changes in the Hen. P.iRT III.— Local Variations in the Plumage of the Grouse. IV.— Food of the Red Grouse 67 Part I. — Observations on the Food op Grouse, based on an examiuation of crop contents. By Edward A. Wilson. Part II.— The Insect Food of Grouse Chicks, based on an examination of croi)s and gizzards. By Percy H. Grimsilwv. Part III.— Water. By A. S. Leslie. Part IV.— Grit. By Dr H. Hammond Smith and R. H. Rastall. v.— Physiology and Anatomy of the Red Grouse. By Edward A. Wilson . loO VI.— The Weight of Grouse. By Edward A. Wilson 130 Part II.— THE GROUSE IN DISEASE. VII.— Causes of Mortality in the Red Grouse. By Lord Lovat and Edward A. Wilson 147 VIIL— Causes of Mortality in the Red Grouse — continued. By Edward A. Wilson 152 Part I. — Those Referable to Artificial Conditions. Part II.— Those Referable to N.vtural Causes. IX. — Grouse Disease. By Edward A. Wilson and A. S. Leslie .... 185 History of Grouse Disease with an account of the work of the Grouse Disease Inquiry in respect of previous work done by Professor Klein, Dr Cobbold, and others. vii viii TABLE OF CONTENTS CHAPTER PAOB X.— Grouse Dise&se-'conthived — Strong'ylosis 207 Part I.— The Threadworms {Xeuatoda). By Di- A. E. Shipley. Part II.— On the Development and Bionomics of TRU-HnsTmsnYLVS pergbacius. By br R. T. Leiper. XI.— Grouse Disease— c"«^/'»/«''^?—Coccidiosis. By Dr H. B. Fantham . . .235 Part I— The Morphology and Life History of EmEF.iA (Coccidium) avii'm, a si^orozoon causing; a fatal disease among young Grouse. Part II.— Experimental Studies on Avian Coccidiosis, especially in relation to young Grouse, fowls, and pigeons. Part III.— Coccidiosis in Game Birds and Poultry : Some Preventive Measures and Treatment. XII.— Grouse Disease — con!!/«7(«/— Pathology. By Dr L. Cobbett and Dr G. S. Graham-Smith 273 XIII. —Observations on the Blood of Grouse. By Dr H, B. Fantham . . 308 XIV.— Observations on the Parasitic Protozoa of the Red Grouse (Lagopus scoticus) with a Note on the Grouse Fly. By Dr H. B. Fantham . 318 XV.— The Tapeworms {Cestoda) of the Red Grouse {Lagopus scoticusj By Dr A. E. Shipley 334 XVI.— The Ectoparasites of the Red Grouse {Lagopus scoticus). By Dr A. E. Shipley 347 Part Ill.—MANAGEMENT AND ECONOMICS OF GROUSE MOORS. XVII.— Moor Managrement. By Lord Lovat 372 XVIII.— Heather-burning-. By Lord Lovat. 392 XIX.— The Heather Beetle. By P. H. Grimshaw 414 P.VRT I.— On "Frosted" He.\ther and its cos-NECTroN with the He.\ther Beetle {Lochm.ka suti-ralis). Part II.— The Life History of the He.\ther Beetle. XX.— Keepers and Keepering-, with sub divisions dealing- with Poachers and Vermin. By Lord Lovat .......... 430 XXL— Stock. By Lord Lovat 454 XXII.— Grouse in Captivity. By Dr H. Hammond Smith 483 XXIII.— Value of Grouse Shootings in Great Britain By A. S. Leslie . 491 Index 503 LIST OF ILLUSTRATIONS I. II. III. IV. V. VII. VIII. IX. X. XI. XII. Xlll. XIV. XV. XVI. XVII. xviir. XIX. XX. XXI. XXII. XXIII. XXIV. XXV. XXVI. XXVII. XXVII«. XXVIII. XXIX. XXX. XXXI. P.^IR OF RED GROUSE IN SUMMER WITH YOUNG CHICKS MALE GROUSE, BLACK TYPE, IN FULL WINTER PLUM.\GE M.VLE GROUSE, RED TYPE, IN FULL WINTER PLUMAGE . MALE GROUSE, WHITE SPOTTED BIRD OF RED TYPE MALE GROUSE, RED TYPE, IN FULL WINTER PLUM.AGE WITH A FEW BL.iCK CENTRED FE.VTHERS OF THE PREVIOUS AUTUMN PLUM.\GE MALE GROUSE SHOWING MARKED BEGINNIN<; OF THE AUTUMN PLUM.AGE ON HEAD AND NECK .......... MALE GROUSE CHANGING FROM WINTER TO AUTUMN PLUMAGE FEM.\LE GROUSE, BLACK TYPE, IN AUTUMN PLUMAGE .... FEMALE GROUSE, RED TYPE, CHANGING FROM WINTER TO SUMMER PLUMAGE FEMALE GROUSE IN FULL BREEDING PLrMAGE ..... FEMALE GROUSE IN FULL SUMMER PLUMAGE ..... FEMALE GROUSE, RED TYPE, FE.ATIIERS FROM FLANKS .... FEET OF RED GROUSE: (1) NEW WINTER FEATHERS AND NAILS; (2) FULL WINTER PLUMAGE ; (3), (4), (3) AND (6) SHOWING STAGES IN MOULTING OF NAILS FEMALE GROUSE, SHOWING BARE PATCH OF SKIN AND DOUBLE LINE OF BARRED FE.ATHERS ON ABDOMEN ..... FEMALE GROUSE, RED TYPE, WORN UPPER TAIL COVERTS HEADS OF (1), (2), FEMALE GROUSE; (3), (4), MALE GROUSE; (.5) PT.\RMIGAN SHOWING SUPRA-ORBITAL COMBS .... HEAD OF BLACKCOCK SHOWING SUPRA-ORBITAL COMB MALE GROUSE SHOWING ABNORMAL ERYTHRISM FEMALE GROUSE, BUFF-BARRED TYPE FEMALE GROUSE, ABNORMAL YELLOW VARIETY FEMALE GROUSE, GREY VARIETY FEM.ALE GROUSE, GREY VARIETY TYPES OF HEATHER .... PLANTS EATEN BY THE GROUSE (4 Figures) PLANTS EATEN BY THE GROUSE (4 Figures) DIAGRAM OF ALIMENTARY TRACT ALIMENTARY TRACT, CyECUM, RECTUM, GIZZARD, DUODENUM, SMALL INTESTINE ALIMENTARY TRACT IN SITU . C/ECUM, DUODENUM, ETC. RECTUM AND SMALL INTESTINE C^CA ...... C-iECA AND KIDNEYS .... TEXT-FIG. 1. FRACTURED HUMERUS AND SC.\PULA RE-UNITED . ,, 2. THE SAME BONES UNINJURED .... ,, 3. FRACTURED AND RE-UNITED BREASTBONE OF A GREY HEN ix Fronfhpiece to face page 34 34 34 35 36 36 44 45 45 46 46 46 47 47 48 49 60 60 60 60 60 71 86 87 101 102 103 104 113 117 118 pnqe 154 ,, 1.54 ,, 1.58 LIST OF ILLUSTRATIONS TEXT-FIG. 4, 5. FRACTURED AND RE-UNITED BREASTBONE— VIEWS OF RIGHT AND LEFT SIDE .... „ 6. FR.iCTUHED AND RE-UNITED BREASTBONE SHOWING METHOD OF UNION „ 7, 8. BROKEN AND RE-UNITED WING-BONES .... ,, 9-11. BROKEN AND RE-UNITED LEG-BONES .... „ 12-15. BROKEN AND RE-UNITED THIGH-BONES. XXXII. BUMBLEFOOT IN GROUSE ........ XXXIII. TRICHOSTRONGYLUS I'ERGRACILIS AND TItlCHOSOMA WNGICOLLE (5 Figures) TEXT-FIG. 16. MORULA IN EGG OP TRICBOSTRONGYLUS PERGRACILIS . 17, 18. DEVELOPING OVA OF T. PERGRACILIS .... 19, 20, 21. FORMATION OF THE LARVA OF T. I'ERGRACILIS . 22, 23. EMBRYOS OF T. PERGRACILIS HIGHLY MAGNIFIED . 24-27. CHANGES IN T. PERGRACILIS DURING ECDYCIS AND ENCy.ST.MENT 28, 29. LARVAL FORMS OF T. PERGRACILIS .... 30. ENCYSTED LARV/E OF T. PERGRACILIS .... XXXIV. EIMERIA {COCCWIUM) AVIUM {SCniZOGOn\) . ..... XXXV. EIMERIA (COCCIDIUU) AVIUM (MACROGAMETE FORMATION) XXXVI. EIMERIA (COCCIDIUM) AVIUM (MICROGAMETES SPOROGONY) XXXVII. EIMERIA (COCCIDIUM) AVIUM (SPOROGONY) ...... TEXT-FIG. 1. DIAGRAM OF LIFE-CYCLE OF EIMERIA (iVCCIDIl'M) AVIUM XXXVIII. AVIAN COCCIDIOSIS ......... XXXIX. (1) APPARATUS FOR M.^KING CULTURES .4ND (2) ALIMENTARY CANAL OF GROUSE XL. TEST TUBES CONTAINING T. PERGRACILIS (2 Figures) .... XLI. SECTIONS OF CECUM SHOWING T. PERGRACILIS (6 Figures) XLII. T. PERGRACILIS and D. UROGALLI (4 Figures) ..... XLIII. SECTIONS OF CECUM (6 Figures) ....... XLIV. DIAGRAM OP ALIMENTARY CANAL SHOWING HABIT.VTS OF INTESTINAL PARASITES XLV. BLOOD CELLS OP BIRDS CHIEFLY OF GROUSE ..... XLVI. LEUCOCYTOZOON LOVATI ........ XLVII. LEUCOCYTOZOON LOVATI, SPIROCH.IiTA LAGOl'ODIS AND lI.EMOl'ROTEUS MANSONI . XLVIII. TRICHOMONAS EBERTHI, SPIIIOCH.KTA LOVATI, AMCEBA LAGOPODIS XLIX. DAVAINEA UROGALLI ..... L. D. UROGALLI AND HYMENOLEPIS .MICIIOI'S . LI. D. UROGALLI, HYMENOLEPIS MICIIOPS, ETC. (7 Figures) LII. HYMENOLEPIS MICROPS .... LIII. GONIODES TETRAONIS (4 Figures) . LIV. NIRMUS CAMERATUS (2 Figures) . ... LV. ORNITIIOMYIA LAGOPODIS (3 Figures) LVI. CERATOPHYLLUS GAI.I.INUL.E, ETC. (3 Figures) LVn. HEATHER GROWING FROM THE ROOT AND FKOM SEED LVIII. THE HEATHER BEETLE (LOCHM.EA SUTURAI.IS) (4 Figures) Page 159 V „ 100 „ 102 „ 163 „ 164 to face page 170 209 ■paye 219 „ 221 „ 221 „ 223 „ 225 ,, 227 „ 227 to fact page 238 240 243 245 page 248 to face page 2.52 278 283 285 287 288 290 309 319 320 326 335 336 337 342 350 357 358 361 401 126 INTRODUCTION By Lord Lovat Before the formal appointment of the Committee in 1905 the following preliminary work of organisation was carried out. On June 5th, 1904, the organisers of the present investigation met, and after discussion formed a Committee of Inquiry to investigate the subject of " Grouse Disease." The following gentlemen were present : The Marquis of Tullibardine, Lord Lovat, Mackintosh of Mackintosh, Mr R. H. Rimington Wilson, Mr J. Graham, Mr D. W. Drummond, Mr R. C. Munro Ferguson. Lord Lovat was appointed Chairman, and Lord Onslow, the then President of the Board of Agriculture, was approached with the view of obtaining the assistance of that Board. A further meeting was held in December of the same year, when the details of the proposed lines of inquiry were discussed, a Secretary was appointed, and a number of witnesses were examined. The formal appointment of the Committee as a Departmental Committee of the Board of Agriculture and Fisheries was intimated by the Secretary of the Department on April 13th, 1905. The terms of the appointment marked a departure from the usual procedure in such matters, for they provided that no public funds should be devoted to the Inquiry, but that the investigation should be conducted at the expense either of the members of the Committee or of private subscribers. The members included the above-named gentlemen, with the addition of Earl de Grey (now Marquis of Ripon) and Lord Henry Scott. Dr William Somerville was appointed to represent the Board of Agriculture and Fisheries, and upon his retirement from the Board Mr T. H. Middleton was appointed. The Committee sustained a severe loss by the death in 1910 of Mr James Graham, one of its most active and capable members. In April and May 1905 an appeal was sent to a limited number of proprietors and tenants of Grouse moors asking for financial support. This appeal resulted in subscriptions amounting to over £400 ; these subscriptions were limited to a sum xi xii INTRODUCTION not exceeding £5 a year, and in the majority of cases were guaranteed for a period of three years. On the strength of this response a number of scientific gentlemen were asked to assist in the investigation, and a body of local corre- pondents in different parts of the country was appointed to make observations and to report upon any special local conditions or circumstances affecting Grouse in their respective districts. These local correspondents consisted mainly of resident proprietors, factors, estate agents, and gamekeepers. Great care was taken in their selection, and experience has shown that they have fully justified their appointment. About three hundred correspondents were formally appointed, and many other proprietors and gamekeepers corresponded regularly with the Secretary and with the staff of the Committee whenever occasion arose. The list of local correspondents might easily have been doubled by adding to it the names of those who had shown themselves able and willing to assist the investigation, but unfortunately the funds of the Committee would not admit of such addition. Lists of the Committee, of the staff, and of the local correspondents are given in Appendix A. For the instruction of local correspondents and others who wished to be informed of the existing state of knowledge on the subject of " Grouse Disease," and further to indicate the exact points upon which information was required, the Committee drew up an illustrated pamphlet entitled " Notes on the Grouse " ; in this a short summary was given of the life history of the bird, with a description of the typical characteristics of " Grouse Disease " as then recognised. The pamphlet called attention to the many theories which existed on the subject, and indicated the lines upon which the Committee proposed to carry out their investigation. This pamphlet was privately circulated among correspondents and subscribers, but was not offered for sale. The scientific experts drew attention to the difficulty of carrying out experiments upon Grouse in a wild state, and accordingly in 1906 the Committee established an observation area in Surrey, where it was soon demonstrated that Grouse could be kept in captivity. The necessary licence was obtained from the Home Office. This observation area has been of the utmost value to the Committee. Owing to the necessity of having a constant supply of healthy Grouse for examination in every month of the year, to enable the Committee to collect accurate information on the question of feeding, moulting, and seasonal changes, arrangements were made by members of the Committee and certain local corre- spondents to send to the Field Observer each montli of the year a certain number of freshly killed birds. Many hundreds of such birds have been examined, and INTRODUCTION xiii from the material so obtained valuable, and in many cases new information was gained. An interesting collection of over six hundred Grouse skins has been prepared, showing the types of plumage found in both sexes at different times of the year and in different districts, and also certain abnormalities. Selections from this collection and from the other material collected by the Committee were exhibited at a soiree of the Royal Society in May 1909, and at the Vienna Sports Exhibition of 1910. The Committee began their observations in the field in the autumn of 1905 ; durino- this season and 1906 the stock of Grouse both in Scotland and England was remarkably healthy, and an excellent opportunity was thus given to study the bird under normal conditions. The Field Observer visited many moors, his visits extending over a period of seven months, from April to October. During this time he got into close touch with the Committee's correspondents in different parts of the country, checked their information, and with their assistance studied the varying conditions governing particular districts. Whenever a case of suspected " Grouse Disease " was reported the moor was visited by the Field Observer or one of his assistants, and specimens of suspicious birds were subjected to laboratory examination. During 1907 a considerable mortality amongst the Grouse in certain districts was reported in the spring and early summer months. The Committee's experts made a very careful investigation into every case reported, but, contrary to expectation, it was not found that the character of the disease differed materially in its essential features from those occasional isolated cases of mortality which had occurred in the previous year. The Committee found no examples of the acute or sudden form of disease which had been described by former observers. The out- break of mortality, however, gave an excellent opportunity for collecting data regarding the lingering or pining form of disease which has since been traced to the ravages of the threadworm Trichostrongylus pergracilis.^ By 1908 the Committee had completed the preliminary work required to enable the subject to be developed on scientific lines. Evidence and statistics had been collected which indicated the special directions in which further investigations were necessary or likely to be helpful. The natural history of the normal healthy Grouse had been fully studied, and the general pathological characteristics of " Grouse ' In the following chapters this worm is usually called Triclwstrongijlus pergracilis, but some writers have preserved Strongylus pergracilis, it is also at times called the Strongyle or the Strongyle worm. A synonym and a list of allied species are given by Dr Shipley on pp. 207 et seq. xiv INTRODUCTION Disease," from a field observer's point of view, had been ascertained. Even at this date the Committee were of opinion that they had discovered the principal causes of mortality amongst Grouse ; but until they had further confirmed their suspicions they decided not to publish anything in the nature of results. It was at this stage that an impatient public and the necessity to stimulate dilatory subscribers forced upon the Committee the necessity of publishing some account of their progress, and the Interim Report issued in August 1908 was the outcome of this demand. The Interim Report contained an account of the work done by the Committee up to date, but omitted all reference to the results which had only been achieved in part. During the second or research stage of the investigation the following special points were studied: (l) The life history of the Trichostrongylus jjergracilis, which the Committee believed to be the immediate cause of " Grouse Disease " ; (2) The life history of the other internal parasites of Grouse ; (3) The protozoal parasites infecting the alimentary tract and blood of Grouse ; (4) The bacteriology of Grouse ; (5) The various insects found on the moors both from the point of view of insect-borne disease and from the point of view of food ; (6) The questions afiecting the food supply of Grouse, including the management of heather land, causes of destruction of heather, e.g., frost, heather-beetle, etc. These lines of research were diligently followed up by the members of the Committee's Scientific Staff during the last three years of the Inquiry — the work entailed long series of experiments carried out upon the open moor, in the labora- tory, or at the Frimley observation area. The results have been unexpectedly conclusive, considering the short time available for so great a task. The Committee consider that although their immediate object has been achieved, viz., the elucidation of the causes of "Grouse Disease," the present Inquiry has scarcely crossed the threshold of the investigation into the general pathology of birds, and there is still a large amount of work which might be profitably under- taken. The most important department of the research, so far at least as relates to mortality amongst adult Grouse, was the investigation of the life history of the strongyle threadworm. The work was rendered difticult owing to the small size of this parasite, but thanks to the efforts of Dr Wilson, Dr Shipley, and Dr Leiper, we are now in a position to speak with something approaching certainty on the subject. These gentlemen have worked at the subject for more than three years, and have not only ascertained the life cycle through which this worm passes, but have discovered the conditions which are favourable or preju- INTRODUCTION XV dicial to its growth ; they have been able to rear the young strongyle, and by administering it through the medium of food to hand-reared Grouse free from nematode infection, have infected the hand-reared birds with " Grouse Disease." Another interesting and important outcome of the Inquiry has been the discovery of a cause of death among Grouse in their infancy due to the presence of an intestinal parasite known as Eimeria (Coccidium) avium. It is unfortunate that the Inquiry is being brought to a close while Dr Fantham is still engaged in tracing the predisposing causes of this disease with a view to finding whether any preventive measures are possible. It is true that such preventive measures, even when found, might not be easily applied to the Grouse in a wild state ; but they would be of the greatest possible value for the treatment of hand-reared game-birds or domestic fowls. During the progress of the Inquiry many questions afiecting Grouse and Grouse shooting, but not directly connected with disease, have come before the notice of the Committee, and owing to their general interest to readers of the Eeport it has been thought well to refer to some of them. Since the Inquiry has been mainly supported by those whose interests are more intimately connected with sport than with science, the inclusion of chapters on such subjects of practical importance as Moor Management, Heather-burning, Vermin, Keepers and the Value of Grouse moors, requires no apology. The chapters of natural history, such as Life History, Plumage changes. Food, Physiology and Death from Causes other than Disease, are all indirectly connected with the main subjects of the Inquiry. It will be seen that by the inclusion of the above-mentioned chapters the Report of the Committee becomes a monograph on the Red Grouse in health and disease rather than a summary of the proceedings of a Departmental Committee of Inquiry. During the period of the Inquiry a large number of Pamphlets, Reports, and Letters of Instructions have been printed and issued by the Committee to its local correspondents and other supporters. These documents, in addition to the " Notes on the Grouse " pamphlet already referred to, include Notes of Evidence taken at the meetings of Committee, Lists of Queries, Forms of Particulars of Specimens, Periodical Reports on the Progress of the Inquiry, Lists of Subscribers, Lists of Local Correspondents, Statements of Crop-contents, Circular Letters to Proprietors, etc., etc. In all more than 40,000 printed documents have been circulated, in addition to a large number of typewritten circulars and letters, of which no accurate record has been kept. The correspondence both of the Secretary and the Field Observer has been XVI INTRODUCTION voluminous, and has sometimes been subject to such sudden bursts of activity that it was found well-nigh impossible to keep pace with it. To this cause must be ascribed occasional failures to acknowledge written communications by return of post, for which failures the Committee now tender their apology. In the course of the investigation many technical questions arose which made it necessary to employ the services of leading scientific experts, and, owing to the difficulty in obtaining immediate and definite results, it was found that the period of the Inquiry would have to be extended beyond the three years originally fixed. The result has been that the Committee found it necessary to exceed their original estimates. During the whole Inquiry the Committee has been greatly hampered in their labours by lack of funds. The total income has never amounted to £1,000 in anv one year, and the work would have been in danger of coming to an end were it not that many members of the Scientific Staff" have given their services gratuit- ously or for at most a nominal consideration. What success the Committee have met with is due to several causes. Firstlv, the work was, in the main, directed by small Sub-Committees who were unham- pered by official restrictions and untrammelled by traditional red tape. Secondly, the Chairman and the Secretary had the cordial support not only of the other members of the Committee but of all those directly or indirectly interested in the Grouse. Thirdly, the members of the Scientific Staff" took the keenest interest in the problems they sought to solve, and were willing to place their knowledge, their spare time, and their technical skill at the disposal of the Committee unremunerated, or at best remunerated at an entirely inadequate scale. Fourthly, the Inquiry aroused a certain public spirit, which not only found expression in the willingness of sportsmen, landlords, keepers, and others to do all in their power to assist the work of the Committee, but led the printers, the firm which supplied the paper upon which the book is printed, the publishers and many others connected with the preparation of the volume, to grant the Committee the most favourable terms. That this Inquiry did not cost more than the small sum of £4,366 in the six years over which the work extended (averaging £727 a year) is due to the causes set forth above, and to the constant vigilance and unselfish insistance on economy on the part of the Secretary. Compared with the cost of similar Royal Commissions and Departmental Committees this sum is a mere trifle, but it shows that satisfactory results can be attained at very small expense. Much money was of course saved liy not printing the evidence given at the numerous examinations of gamekeepers ^1 INTRODUCTION xvii and others held by the Committee. Such evidence is, as a rule, printed in full, and remains unheeded and unread in tons of neglected Blue-Books. Then again the money has been carefully and laboriously collected, for the Committee were precluded by the terms of their reference from drawing on the purse of the tax- payer. This also made for economy. Some criticisms have been heard at the delay which has occurred in the produc- tion of this volume. But it should be remembered that when the Inquiry started very little was accurately known about the Grouse either in health or in disease. As a member of the Scientific Staff said in a lecture before the Royal Institution : " In considering exceptions it is so immensely important to know the rule. In studying disease our starting-point should be the normal, the healthy ; yet until lately no one has closely studied the healthy Grouse, and indeed it is almost impossible to find a normal Grouse, i.e., one free from parasites. A Grouse cannot express to us its feelings ; the state of its tongue, the rate of its pulse, even its temperature tell us nothing because we have no norm and no means of estimating the extent to which a diseased Grouse has departed from the standards of a healthy bird. The nature of the numerous kinds of blood corpuscles, which alter in proportion so markedly in animals when they become parasitised, was but a few months ago quite unknown, the "blood count" uninvestigated; in fact the Inquiry started, as regards the cause and symptoms of the diseases which affect Grouse, practically behind scratch." Further, the Committee were not in a position to retain the whole time of any one of their Scientific Staff with the single exception of the Field Observer. What work this staft" have accomplished, and they have accomplished much, has been for the most part done in their spare time or during their brief holidays. Another factor that made for delay was that the Committee were not in a position to establish a central laboratory, and hence the actual investigations were carried on for a time in one place, and then after a break often of many weeks the threads were picked up in another. Much work was done at Cambridge, but at the London School of Tropical IMedicine, at the Royal Scottish Museum, Edinburgh, at Frimley, at King's School in the Isle of Man, in the offices of the Field in London, in the gun-room at Beaufort, valuable investigations were also carried on. Further, from the necessity of examining absolutely fresh material, an improvised travelling laboratory had to be set up perhaps in a private sitting-room of a country hotel, perhaps in an outhouse of a Highland inn, but always under conditions which vastly increased the difficulty of investigation, and made for delay. xviii INTRODUCTION Considering aJl these circumstances, the results now published do not seem unduly belated. The Committee specially desire to record their thanks to the following gentle- men who have formed the Scientific Staff of the Inquiry, and to wliose labours the results are due : — Edward A. Wilson, M.B., F.Z.B., M.B.O.U., was appointed, in November 1905, principal Field Observer, Anatomist and Physiologist to the Inquiry, and devoted his whole time to the work till the autumn of 1910, when he joined Captain Scott's Antarctic Expedition as Scientific Director on the Terra Nova. It is difficult to speak highly enough of Dr. Wilson's services, for not only was he an indefatigable worker in the field, but his ornithological knowledge, his scientific training, and his artistic skill, have been of the utmost value in every branch of the Inquiry. Practically every Grouse which was submitted to the Committee for examination was dissected and reported on by Dr Wilson, and the results of these dissections, as shown in Appendix D, not only form a record of long and patient labour, but also provide an enormous mass of carefully arranged material which has been of great use to the Committee. Dr Wilson has written or aided in writing ten out of the first fourteen (Chapters of the Book, and has not only fully illustrated his own contributions, but has placed his artistic skill at the disposal of nearly all the other writers. In addition to his services as Field Observer and Physiologist, Dr Wilson conducted a series of experiments on live Grouse at the Committee's Observation Area whereby the results obtained by Dr Leiper, Dr Shipley and others were put to the test ; these experiments entailed some years of hard and patient work, and required the closest co-operation with the other members of the Scientific Staff. Dr Wilson's personal qualities secured for him the willing assistance alike of Local Correspondents and Scientific Staff, and went far to ensure whatever success the Committee has achieved. A. E. Shipley, M.A., Hon. D.Sc, F.R.S., Master of Christ's College, Cam- bridge, and Reader in Zoology in the University of Cambridge, undertook in June 1905 to assist the Committee in the Scientific Depai'tments of tlieir research, especially in connection with the investigations of the ectoparasites and endoparasites of Grouse. Dr Shipley's services to the scientific side of the Inquiry have been as important as Dr Wilson's services to the natural history side. Dr INTRODUCTION xix Shipley has published the results of his labours in the Proceedings of the Zoological Society of London for 1909 in the following series of articles : (1) The Tapeworms (cestoda) of the Red Grouse; (2) The Threadworms (nematoda) of the Red Grouse; (3) The ectoparasites of the Red Grouse ; (4) The Internal Parasites of birds allied to the Grouse. The first thi-ee of these papers are, by the courtesy of the Zoological Society of London, reprinted with minor alterations in the present Report. Dr Shipley has also acted as one of the Publishing Sub-Committee of the Inquiry, and has given much assistance in the revisal of the proofs and the preparation of Interim and Final Reports for the press. R, F. Leiper, D.Sc, M.B., F.Z.S., Helminthologist to the London School of Tropical Medicine, was appointed in 1908 to help in the elucidation of certain diflBcult questions relating to the life history of the nematode worm Tricliostrongylus pergrcicilis, which in the opinion of the Committee is the main cause of mortality in adult Grouse. Dr Leiper devoted much time to the study of these questions, and to him is due the credit of having solved many of the problems connected with the development and bionomics of this important parasite. The result of his investiga- tions are given in the present Report. W. Bygrave and Percy H. Grimshaw assisted Dr Shipley by a prolonged and systematic search for the intermediate host of the Grouse tapeworms, and though the results were negative, the conscientious manner in which the search was conducted has enabled the Committee to claim that the question has been investigated as fully as was possible in the time at their disposal. H. B. Fantham, D.Sc. Lond, B.A. Cantab., A.R.C.S., F.Z.S., Christ's College, Cambridge, Parasitologist to the Liverpool School of Tropical Medicine, formerly Assistant to the Quick Professor of Biology in the University of Cambridge, was appointed Protozoologist to the Inquiry in 1907, and since that date has made a careful study of the protozoal parasites which are found in the blood and alimentary tract of the Grouse. His researches have resulted in a most interest- ing series of discoveries, of which by far the most important from the Committee's point of view is that the Eimeria {Coccidium) avium frequently found in the alimentary tract of the Grouse is a frequent cause of death of young birds. Dr Fantham has followed up and fully described the life history of this parasite, whose presence in the intestine of the young Grouse was first pointed out by Dr. Leiper, and has published the results of his researches in the Proceedings of the Zoological Society of London for October 1910 in the following series of articles: (1) The XX INTRODUCTION Morphology and Life Hiatovy of Eimeria (Coccidium) avium: a Sporozoon causing a fatal disease among young Grouse ; (2) Observations on the Parasitic Protozoa of the Red Grouse (Lar/ojyus scoticus) ; (3) Experimental studies on Avian Coccidiosis, especially in relation to young Grouse, Fowls and Pigeons ; (4) Observa- tions on the Blood of Grouse. By the courtesy of the Zoological Society of London tliese articles are reprinted in the present Report. C. G. Seligmann, M.B., then Pathologist to the Zoological Society of Loudon, was appointed in 1906 to investigate the bacteriology of "Grouse Disease." He worked for the Committee till the end of 1907, when he left for Ceylon on a scientific, expedition. The Committee is indebted to him for the discovery that the bacterial characters observed by Professor Klein as symptomatic of "Grouse Disease " were not in fact the pathological accompaniment of the mortality in Grouse as observed by the Committee. After Dr Seligmann went abroad his observations on this point were continued and confirmed Ijy Dr Cobbett and Dr Graham Smith. L. Cobbett, M.D., F.R.C.S., University Lecturer in Pathology, Cambridge, and G. S. Graham-Smith, M.D., University Lecturer in Hygiene, Cambridge, consented in 1909 to continue the work where Dr Seligmann had left off. They made an exhaustive investigation of the general pathology of "Grouse Disease" in all its forms, and the relation of the Bacillus coH of Professor Klein's " Grouse Disease " to the various pathological lesions which had come under the observation of the Committee. The results of their investigations were published in the Jo>iriial of Hygiene in June 1910, and, by the courtesy of Professor Nuttall, the Editor of that Journal, ai-e reprinted in the present Report. L. W. Sambon, ^I.D., gave considerable assistance to Dr Seligmann during the spring of 1907, and discovered a new leucocytozoon in the blood (X. Lovati). H. Hammoxd Smith, M.B., Pathologist to the Field newspaper, has assisted the Committee both in the field and in the laboratory since the Inquiry was commenced. He established and organised the Observation Area at Frimley iu Surrey, and gave great assistance to the Committee in connection with the conduct of experiments at this Observation Area. He also assisted in the study of the question of the grits found in the gizfcirds of the Grouse and other game birds, and gave great help to the Committee in connection with the conduct of experiments at tlie Observation Area. INTRODUCTION xxi R. H. Rastall, M.A., F.G.S., Fellow and Lecturer of Christ's College, Ciimbridge, drew up an interesting report on the mineral constituents of gizzard grits iu Grouse, and gave assistance in writing the article dealing with grits which appears in this Report. He also aided the work of publication by reading and correcting almost the whole of the proofs of this Report. Percy H. Grimshaw, F. R.S. li, F.E.S., Assistant Keeper of the Natural History Department, Royal Scottish jNIuseum, was appointed iu 19U9 to undertake the whole investigation of the insect life on the moors. He carried on and elaborated the work begun by ^Ir Fryer and Mr Hill, and not only prepared a complete list of the insects found on the moors, but also reported upon those eaten by the Grouse as shown by an examination of their crops and gizzards. The result of his work is published in the " Annals of Scottish Natural History" for July 1910, and in chapter iv. and Appendix E of the present Report. Mr Grimshaw also undertook the investigation of the habits and life histoiy of the heather Ijeetle {LochnuBa sutnralis), and his article on this subject is included in the Report. George C. Muirheau, B.Sc, acted as Field Observer from May to December 1905, and assisted in drawing up the pamphlet " Notes on the Grouse." J. C. Fryer, B.A., Gonville and Caius College, Cambridge, was appointed in 1907 to make a report on the Insect Life of Grouse Moors. This Report has already appeared in the Interim Report of the Committee. Alfred Hill was employed in 1908 to carry on the investigations already commenced by Mr Fryer. A. S. Leslie, B.A., W.S. As soon as the Committee was otKcially appointed in 1905, one of their first acts was to nominate Mr Leslie as Secretary. During the six years that the Committee have sat he has continued to act in that capacity, and his duties have been both varied and arduous. To him was entrusted the task of collecting the subscriptions, which formed the sole source of income for the Inquiry, and without which nothing could be done ; the control of this Fund further rested in him. He also got together and organised the three hundred and sixty local correspondents, he drew up all the various tables, forms, etc., with which these correspondents were supplied, received the answers to the questions asked, collated and tabulated not only these answers but the verbal xxii INTRODUCTION replies given at the several examinations of gamekeepers and other experts, which from time to time the Committee held. His correspondence amounted to many thousands of letters. Further, he assisted the Field Observer in many ways, especially in the preparation of statistics and the arrangement of tabular matter. Mr Leslie wrote the "Notes on the Grouse," and has been in the main responsible for the preparation and seeing through the press both the Interim and the present (Final) Report ; the compiling of the appendices and the index, and the revision of the proofs, were largely his work. To his knowledge of Scotland and of sport, and his professional training, the Committee owe many valuable suggestions as to the course the investigations have from time to time taken. They feel they cannot speak too highly of the self- sacrificing way he has thrown himself into the work, of his untiring energy, of his powers of organisation or of his adaptability and tact, which has done much to make the labours of not only the Committee but of all in any way associated with the Inquiry not only profitable but pleasurable. The salary that the Committee have been able to otter to Mr Leslie can only be described as derisory. He has, in fact, received but the scantiest payment for the work he has done, and no compensation of any kind for the time he has taken from his profession and given to the Inquiry. But not only has he, like others, given time, skill and knowledge to further the cause of the investigation, but l)y his skilful husbandry of the limited resources available he has enabled the Com- mittee to cover a wider area of research, and to prolong the time during which research was carried on to an extent whicli at first seemed impossible. R. B. Fraser was appointed Assistant Secretary in October 1907, when it was found that the work of organisation and correspondence could not be conducted single handed by the Secretary. Mr Fraser has given valuable assistance with the general secretarial work, and also with the additional work entailed in con- nection with the preparation of the Report for the press. In addition to those already mentioned the following have given the Committee much assistance in the revisal of proofs and in other ways : W. Berry, B.A., LL. B., M.B.O.U., who has been chiefly responsible for the Index ; W. R. Ogilvie Grant, M.B.O.U., of the British Museum of Natural History ; W. Eagle Clark, F.L.S., F.R.S.E., etc., Keeper of the Natural History Department of the Royal Scottish Museum; L. R. Sutherland, M.B., Professor of Pathology in the INTRODUCTION xxiii University of St Andrews ; Mrs E. A. AVilson, and the Hon. Gladys Graham Murray, F.Z.S. An Abstract of Accounts is annexed, from which it may be seen how the income has been expended.' The whole funds have now been exhausted in the work of investieation, and there is no balance available to meet the cost of publishing the results. This is to be regretted, as it will make it impossible to provide the supporters of the Inquiry with copies of the Report free of charge. The thanks of the Committee are due to those moor-owners, shooting tenants, gamekeepers, and others who have gratuitously given their services as corre- spondents. The Committee have to acknowledge with thanks the support it has received from its subscribers. A list of subscribers and the amount of their subscriptions is given in Appendix B." The Committee have also to acknowleds;e their indebtedness to the Zoological Society of London, which at the request of the Committee published in the Pro- ceedings of the Society the articles on Ectoparasites and Endoparasites of Grouse by Dr A. E. Shipley ; the articles on the Protozoa and Blood of Grouse, by Dr H. B. Fantham ; and the article on the Plumage of Grouse, by Dr E. A. Wilson, comprising an important part of the scientific matter contained in this volume, which is reproduced here by consent of the Society. They have also to acknowledge their indebtedness to the Society for revising and editing the manu- script of Dr Wilson's contributions on the Plumage of the Grouse, in the absence of the author on the Antarctic Expedition. The Committee also desire to acknowledge its indebtedness to the heads of the various Scientific Laboratories at Cambridge, where nmch of the research work was carried on ; to the London School of Tropical Medicine who permitted Dr Lei per to assist in the investigation ; and to the Directors and Staff of the Royal Scottish Museum, who assisted the Committee in A^arious ways during the whole period of the Inquiry. ' Vide vol. ii.. Appendix C. ^ Vide vol. ii.. Appendix B. August 191 L THE GROUSE IN HEALTH AND IN DISEASE PART I.— THE NORMAL GROUSE CHAPTER I THE SYSTEMATIC POSITION OF THE GROUSE By A. H. Evans The name Grouse, in the form " Grows," has been traced back by Salusbury Brereton to the reign of Henry VIH. (1531), and in its present form to 1603. But, since it first occurs in an ordinance for the regulation of the Royal Household at Eltham in Kent, it ought in all probability to be applied the name to the Black Grouse which may then have inhabited that county, though no actual record has yet been discovered. Further particulars are given by Professor Newton in his " Dictionary of Birds." ^ The appellation has, however, by universal consent been long transferred to the Red Grouse, the Moorfowl of our forefathers , and when standing alone would never now be understood otherwise. This species is the most characteristic bird of the Scottish moorlands, including the Hebrides and the Orkneys, and is plentiful thence to the northern counties of England ; in few places is it more numerous than on the Digt,.iiuu. moors of South Yorkshire and Derbyshire in the vicinity of Sheffield ; *'°"- while to the west it not only occurs in decreasing numbers to Shropshire, but is found in Wales as far south as Glamorganshire, and in Ireland in most suitable localities. Attempts have been made to acclimatise it to the north and south of its proper range ; but the few pairs turned down in Acciimati- Shetland between 1858 and 1883, with a greater number in 1901, ^^"°°- have never thriven, while their descendants are apparently extinct, and the same may be said of those introduced into Surrey, Norfolk, and elsewhere, with ' A. Newton, "Dictionary of Birds," p. 388. London : A. and C. Black, 1893-1896. VOL. L 1 A 2 THE GROUSE IN HEALTH AND IN DISEASE three exceptions. The first instance is that noticed by Professor Newton in his "Dictionary of Birds," ^ when Baron Dickson succeeded in acclimatising the species near Gottenburg in Sweden ; the second is that of its introduction in 1893-1894 to the Hohe Venn, a high tract of moorland on the borders of Belgium and Germany, south of Spa, where Red Grouse are still thriving ; and the third the successful experiment on Lord Iveagh's property at Icklingham iu Suffolk in 1903, where the birds, despite the necessity of an artificial water supply on the dry, sandy heaths, had increased in 1909, and apjjeared likely in 1910 to form a permanent colony. In the Hohe Venn district after two failures fifty pairs or more were liberated in August 1894, and by 1901 had increased to about a thousand head in spite of regular shooting. Professor Somerville of Oxford, who has kindly furnished particulars, saw the birds there in September 1910. During the last twenty years it has been strongly borne in upon the general public, as well as sportsmen, that the welfare of the Grouse is an affair of national interest ; for game of every description is becoming less and less a Economic ,• ^ ■ i ^ ^ ip importance luxury of the Hch, and more and more a regular factor of our food supply, facts which cannot be ignored by the modern economist, and are now considered to be well within the province of the Government, which has at last consented to bestir itself in the matter. Here I propose to give a brief account of the position of the Red Grouse in the class of birds. In nearly all linear systems of classification put forward ciassifica- ^Y Mo^lern systematists, whether they start from the highest or from *'°"- the lowest forms of creation, the large order Galliformes — or its equivalent — stands about midway in the carinate or keel-breasted birds, being connected most closely on the one hand with the Falconiformes and Anseriformes, on the other with the Gruiformes and Charadriiformes. Its position is thus well ascertained, and no serious doubts have been raised as to its constituent members, except that the Tinamidse (Tinamous) of South America, which have been sometimes included in it, are now by pretty general consent placed next to the Ratite birds, with keelless breastbone. Under the order Galliformes may be placed in suborders the curious JSIesites of Madagascar, the no less peculiar Oinsthocomus or Hoatzin of northern South America, and the Old World Turnices (Button Quails) with their close ally Pedionomus ; but the only suborder with which we are here concerned is that known by the name of Galli. Under the Galli, again, we need only make ' " Dictionary of Birds," p. 389. THE SYSTEMATIC POSITION OF THE GROUSE 3 passing reference to the group called by Huxley, Peristeropodes, where the toes are all in one plane ; this includes the families Megapodiidee or Mound-Builders of the eastern tropics, and the Cracidse or Curassows of the neotropical countries. Huxley's second group, the Alectoropodes, with an elevated hind toe, is equivalent to the family Phasianidas, which may be subdivided into the subfamilies Numidinse, or Guinea-fowls, of Africa, the Meleagrinas, or Turkeys, of America, the Odontophorina3, or " American Partridges," the Phasianinae, or Pheasant, Partridge, and Fowl alliance of the Old World, and the Tetraoninae. or Grouse. The last-named might well be classed as a separate family Tetraonidse, were it not for the great difficulty of placing correctly such forms as Caccabis (Red-legged Partridge), Francolinus (Fraucolin), and Coturnix (Quail), which are so nearly allied to both Partridges and Grouse that we may even doubt the advisability of allowing a separate subfamily Tetraoninse at all. Grouse, as thus limited, are entirely confined to the Holarctic region, the great majority of the species being inhabitants of the New World, though a fair number, including the fine Capercailzie, the Black Grouse and oistribu- the Hazel Grouse, are to be found in various parts of the Old World. *'°"- The Red Grouse of Britain belongs to Lagopus, the only genus of Grouse common to both hemispheres, in which even the digits are feathered. This contains six well-defined species : the Spitsbergen Ptarmigan (L. hemileucurus) and the Rocky Mountain Ptarmigan {L. leucurus) — only found in the regions after which they are named — the Ptarmigan -of Scotland and the mountains of the Palsearctic area {L. mutus), the " Iceland " Ptarmigan of that island, Greenland and the lower grounds of Northern Siberia and Arctic America {L. rupestris), the Willow Grouse of the north of Europe, Asia, and America (L. albics), and the British bird {L. scoticus) — with which alone we are concerned ■ — -indigenous in no other country. All the forms of the genus Lagopus are anatomically identical, but the Red Grouse differs from the remaining members in that it does not turn white in winter. It has been thought to be merely the local representative of the ° •' ^ . . Variation. Willow Grouse in Britain, though it difi'ers from that species even in its summer plumage, and never possesses white wing-quills. It varies con- siderably in coloration, as will be seen from the following quotation from " The Cambridge Natural History.' "The male in both summer and winter is more or less chestnut-brown above, with black markings and a reddish head ; the lower parts are similar, but are usually spotted with white. In autumn the brown of 4 THE GROUSE IN HEALTH AND IN DISEASE the upper parts becomes buff, and the lower surface is barred with buff and black. Mr Ogilvie-(Trant recognises three types of plumage in the male, a red form with no white spots, from Ireland and Western Scotland ; a blackish variety comparatively rarely found ; and another largely spotted with white below or even above. Intermediate specimens constitute the bulk of our birds. The female exhibits, moreover, a buff-spotted and a buff- barred form ; but in summer she is typically black above with concentric bufi' markings, and buff below with black bars. Her autumn plumage, which continues throughout the winter, is black, spotted with bufi" and barred with rufous." ^ As we write, Mr Ogilvie - Grant has published in the "Bulletin of the British Ornithologists' Club " ^ an elaborate account of the changes of plumage undergone by the Red Grouse, and of the points wherein he differs from Mr Millais and Dr Wilson ; but this is not the place to enter into controversial matters, and our readers must form their own opinions on the subject.' Various reasons have been suggested for the absence of a white winter plumage in the British bird, for which reference may be made to the late Professor Newton's " Dictionary of Birds." * The Red Grouse is not polygamous ; the birds pair very early in the year, and consequently breed at a time when the eggs are apt to be seriously damaged by late frosts, while the young often suffer from similar causes. The Habits Jo usual haunts are moors clothed with heather (Erica) and ling (Calluna), but in some parts at least of the north-west of England they are to be found on hills covered with crowberry {Empetrum), rush (Juncus), and other vegetation, where little if any heather or ling grows. As a rule, the nest is a slight structure of bents and so forth, placed in thick heather or grass, or even on almost bare ground ; the eggs, ranging from five or six ta more than a dozen in number, have a yellowish or huffish white ground-colour, normally blotched and spotted with reddish or blackish brown. The colour of the markings, however, varies considerably ; in some specimens they are purplish or very rich red, in others orange-red. The eggs measure nearly 2 inches by rather more than 1. The cock utters his well-known crow at all seasons ; the hen has a somewhat different note in the mating season, and when in charge of the young. The cock has also a clear ringing cry. The general habits will be dealt with in the later chapters. ' " Caiiibridge Niitviral History," vol. ix.. Birds, p. 338. Cambridge, 1899. 2 "British Ornithologist's Club," vol. xxii. p. 122. London, 1910. " Vide also chap. iii. ■* " Dictionary of Birds," p. 391. CHAPTER 11 THE LIFE HISTORY OF THE GROUSE By A. S. Leslie No precise date can be given at which Grouse begin to pair, for this depends more upon the climatic conditions than upon anything else. In a mild winter Grouse will pair as early as December or January ; but if, after they are paired, the weather becomes rough and stormy they will again congregate in packs, even after the usual date of nesting has arrived. The time at which they select their nesting ground (March and April) is also, to a limited extent, influenced by climatic conditions. On high moors, where the snow lies in late seasons till far into the spring, it some- pairing times happens that during the whole winter, and even up to the po™po™d^ month of April, there is hardly a bird upon the hill, the whole by snow, stock being congregated on the lower -lying moors where there is "black ground" on which food can be obtained. In such seasons it is interesting to observe the return of the stock to the higher parts as soon as the snow begins to melt. As a rule the birds do not pair upon the low ground, but congregate in packs upon the edge of the snow, waiting for an opportunity of returning to breed on their native hill. A good example of this was furnished in the spring of 1908 on a high-lying moor in Inverness-shire. During the preceding winter there had been a heavy fall of snow which lay for many months on the higher ranges, and drove the Grouse down in vast numbers to the lower levels. On the moor referred to there was not a Grouse to be seen until the snow began to melt about the end of April. But at the first sign of thaw the stock began to return, and as each patch of bare ground came into sight a pair of birds arrived as if guided by instinct and commenced to nest. This year the shooting season turned out to be a record one, for upwards of 6 THE GROUSE IN HEALTH AND IN DISEASE five thousand brace were killed upon an area of 20.000 acres, and many more might have been shot without unduly reducing the stock. While heavy snow during the winter may do little harm though it lies till far into the spring, a loss of stock may result where the fall occurs after the birds have returned to their nesting ground on the higher ranges. This snow on occurred on a moor in Ross-shire in the year 1909, when a corre- stock. spondent of the Committee reports as follows : " A heavy snowfall on April 24th put all the birds down to ' black ground.' They never went back to nest, and consequently the high ground, i.e., over 500 ft., was a failure, and the low ground better than usual." Again, a correspondent in AVest Perthshire writes : — " In spring, when the breeding season is approaching a heavy snowstorm of some duration has on several occasions caused a most serious loss of stock, amounting to as much as half or more of the whole number of birds. After such a spring snowstorm and migration, large numbers of Grouse undoubtedly remain to breed on low and favourable moors wdthin, say, ten or fifteen miles. These low moors are very heavily shot every year, but there is a constant migration of Grouse to them, both from overstocked moors, and from the high moors aftected by snow." This is corroborated bj- a corre- spondent in the south of Scotland, who says : "I have an idea that if birds are forced to leave their usual ground (in spring), through deep untrodden snow, a good number may remain away and not return to their former ground." The subject of migration is more fully dealt with in another chapter.^ During the mating season the pugnacity of the cock Grouse is well known, and in captivity the cocks have to be kept separate at this period, or disaster Pufnacitv ^'^^^ Certainly occur. Under natural conditions the fights seldom of cocks. gjj^ fatally; but it is certain that the presence of a quarrelsome cock-bird in search of a mate seriously interferes with the pairing of the other birds in the vicinity. Observation in the field goes to prove that old cocks are more pugnacious than young ones, and as they are less valuable for breed- ing purposes tlie object of every moor-owner is to reduce the number of old cocks by every means in his power. The nest, a slight hollow scratched in the ground and lined with a scanty layer of grass, heather, etc., is usually placed on the sunny side of a tuft of heather, and preference as regards its site seems to be given to an area on which the heather is moderately well grown rather thau where it is ' See chap. xxiv. THE LIFE HISTORY OF THE GROUSE 7 rank. Birds will always nest in a place where they can see all round, if possible, hence their avoidance of long heather.^ -^ ,. ° Nesting. Dry ground is always preferred ; birds will not nest on boggy or damp ground, and are more likely to leave their nests on account of wet than for any other reason. On some moors where the heather has been very closely burnt or the stock is unusually large, the Grouse appear to be unable to find nesting ground exactly suited to their requirements, and on these occasions they will boldly depart from their usual habits and will nest in short heather, flat dead bracken, or even on a bare unsheltered piece of burnt ground, leaving the nest as open as that of the Lapwing. It is important to note that in all cases open sites devoid of all covering are preferred to really long overgrown heather. The time of nesting varies according; to the season and the latitude. As a rule, most of the eggs are laid by the latter end of April and the beginning of jMay ; but a case has been reported of eggs being found as early as -rj^^g ^^ March 28th, and the Rev. W. B. Daniel records that " on the 5th of i^^t'^i^^s- March, 1794, the Gamekeeper of Mr Lister (now Lord Ribblesdale), of Gisburne Park, discovered on the Manor of Tivitten, near Pendle Hill, a brood of Red Grouse seemingly about ten days old, which could fly about as many yards at a time. This was an occurrence never known to have happened before so early in the year." ^ Macdonald states that the hen begins to lay at the end of March, ^ while Macpherson, writing in the Fur and Feather Series, says that "In the Island of Skye April 24th is a decidedly early date for a full clutch of Grouse eofes." * It is an interesting fact that, from the evidence obtained from many moors, of varying altitudes ranging from the south of Wales to the north of Sutherland, there is a difference of only two or three days in the dates when the earliest eggs are found ; March 30th in Yorkshire and Perthshire, and April 1st on high moors in Inverness and Sutherland are dates frequently recorded for the first nest. The date at which the first clutch is completed varies by a full fortnight on high and low ground and on north ' Macdonald in "Grouse Disease" makes the following statement : " Tlie happiest condition in which a nest can be found is in growing heather of about a foot in length, and in the immediate proximity of short young heather." (Macdonald, " Grouse Disease," p. 23. London : W. H. Allen & Co., Ltd., 1883.) And in another place he writes : "Grouse never nest amongst old, rough heather, always in a little tuft at the side or among the bent." (Ibid., p 26). Macpherson in the Fur and Feather Series, states that " It is a fallacy to suppose that Grouse like to nest in very old heather." (Fur and Feather Series, "The Grouse," ji. 22. London : Longmans, Green & Co., 1894.) a Daniel, " Rural Sports," vol. iii. p. 108. London : Longmans, 1812. » "Grouse Disease," p. 99. ' Fur and Feather Series, "The Grouse," p. 21. 8 THE GROUSE IN HEALTH AND IN DISEASE country and south country moors. In Yorkshire by the end of April many birds have begun to sit, while in central Scotland from April 25th to May 20th would probably cover the dates by which the full clutches are complete on most moors. The intervals between the laying of each egg vary enormously in captivity, probably also in nature, depending upon the weather ; for Intervals example, at the Committee's observation area in Surrey it w'as noted of laying, ^j^^^ ^^^^ j^gj^ took twenty -nine days to lay ten eggs — an average of one egg every three days ; another laid only four eggs in twenty-six days, or an average of one egg every six and a half days. The clutch averages from seven to ten, and rarely reaches twelve. Macdonald states that the hen lays eight to fourteen or sixteen eggs,^ while Macpherson gives seven and eight as the most usual number of eggs, and states that Number " Diorc than ten is quite exceptional." - Seebohm, who speaks with "f eggs. authority on all questions of British oology, states that the number of eggs laid would seem " to vary with the propitiousness or otherwise of the season. In very wet and cold springs the smallest clutches contain four or five, and the largest eight or nine ; whilst in very favourable seasons the small clutches are six or seven, and the larger ones from ten to twelve, or even fifteen and seventeen ; but in the latter cases it is probable that the eggs may not all be the produce of one bird. In an average year most nests will contain seven or eight eggs. Birds which breed late on the high grounds do not seem to lay fewer eggs than those which breed early in the more sheltered situations." ^ A correspondent of the Committee in Forfarshire has repoi'ted a case of two Grouse hens sitting side by side — each on six eggs in a double nest ; and the field observer has seen two hens sitting on one nest with twelve eggs. For the following descriptive notes on the eggs of the Red Grouse in his " Birds of Europe," Dresser states that he is indebted to Seebohm : " The ground colour of the eggs of the Grouse is usually a pale olive, spotted and blotched all over with dark red-brown. The spots are frequently so confluent as almost entirely to conceal the ground colour. In fresh-laid eggs the brown is often very red, in some instances almost approaching crimson. It appears to darken as it thoroughly dries, and sometimes almost ajDproaches black. When fresh laid the colour is not very fast, and before the eggs are hatched the beauty of the original colouring is generally very much lessened by large spots ' Macdonald, "Orouse Disease," p. 99. 2 Fur and Feather Series, "Tlie Grouse," p. 22. 3 Seebohm, "British Birds," vol. ii. p. 430. London ; R. 11. Porter, 188.5. THE LIFE HISTORY OF THE GROUSE 9 comuio: oflf altoo-ether, no doubt from the friction of the feathers of the bird when sitting. If the weather is wet when the bird begins to sit this is much more the case. When the colour has once become thoroughly dry it will bear washing in water without injur3^" ^ In his most recent work Mr Dresser adds : " When blown and kept for some time, the ground colour fades to buffy white, and the spots and blotches darken in some cases to blackest brown. Those in (Mr Dresser's) collection measure from TGO by 1'14 to r82 by 1"32 inches. Mr Jourdain gives the average measurement of thirty-six eggs as 45 '56 by 31'8 mm., and the average weight of eight eggs as 1'845 g."^ There is no truth in the belief that disease will follow if the eggs are not well coloured. Very often the uncoloured part of the egg whitens at the same time as the coloured part fades or is washed off, thus making an egg of "bad colour." It is interesting to note that a bird of five years old lays fewer eggs and of a smaller size than a bird of one or two years old. The net yield of the nesting season greatly depends upon the weather in spring ; frost before sitting, snow after hatching, heavy rain following a drouoht when the birds have nested in low-lyins; ground liable to o _ _ J o o Effect submersion, are some of the principal dano-ers to which early broods are of bad ^ ^ ° •' weather on exposed. The eggs also may he lost by a long spell of wet weather, eggs and even up to the jjoint of hatching. This is probably not a matter of common occurrence, but in the spring of 1906 the Committee's field observer saw nest after nest deserted owing to rain. The nests on the low ground fared worst ; in some the eggs did not hatch at all, in others only one half, or even fewer, were productive. The parent birds seem to defy the elements at all times, and during the period of incubation the hen will continue to sit upon her eggs apparently oblivious of the fact that a snowstorm is raging which has j^g^.^ driven every other living creature ofi^ the moor. During such a storm * hens are completely covered with snow as they sit upon the nest, for in hard weather instinct teaches them not to desert the post of duty. Observation of the bird at these times is difficult, for even the most enthusiastic naturalist is not often tempted to explore the higher ranges of the ground in the face of a blinding blizzard. AVe must to some extent form our conclusions by observation ' Dresser, " Birds of Europe," vol. vii. p. 170. London : published by the author 1871-1881. - Dresser's "Eggs of the Birds of Europe," p. 623, PI. lxvii.. Fig. 1. London : published for the author at the Office of the Royal Society for the Protection of Birds, 3 Hanover Square, 1906-1910. mg m mow. 10 THE GROUSE IN HEALTH AND IN DISEASE of after-results, and certainly there is little doubt that the effect of a heavy snowfall, while the birds are sitting, does not appear to produce the number of unhatched clutches of weather-bleached eggs which might be expected. Some- times, no doubt, matters reach the limit of endurance when, urged by the pangs of hunger, the hen is forced to wander away in search of food and grit, and on her return finds all trace of her nest buried beneath a smooth, white drift. Even in this case, all is not lost ; the snow fortunately does not lie long in the months of April and May, and in due time she recovers her nest and resumes her domestic duties. It is recorded that in 1908, on a Midlothian moor, a heavy snowfall during laying-time covered the nests to a depth of 9 inches for a period of ten days ; many eggs were lost, some even being laid on the top of the snow ; in many cases the hen bird returned to her nest after the snow had gone and laid more eggs beside those which had been covered — some of these birds hatched out every egg. Other cases have been reported where the eass were covered with snow for so lona; that their colourinor matter had disappeared, and yet they produced a healthy brood. From observations made upon Grouse in captivity it appears that during the period of incubation the hen will often leave her nest for several days at a time, for no apparent reason, and will return again and hatch out the whole clutch — this power of absenting herself without disaster to her eggs must undor natural conditions stand her in good stead when the severity of the weather Effects of makes the task of incubation unendurable ; but it is only in the earlier "'*'*■ part of the sitting season that her absence is unattended with risk, for once circulation has commenced in the embryo chick the eggs must not be allowed to become cold. Only when the hen is forced to leave the nest on account of heavy rain is there a danger of her deserting the nest permanently — three days of incessant wet will sufKce for tliis. Another danger to which the eggs of Grouse are liable is that of being destroyed by frost while the hen bird is off the nest. This danger is greatest Effects of during the period before the full clutch has been laid, for after incuba- '''°'*'" tion has commenced the hen will not readily leave her nest during frosty weather for any length of time. Before the hen commences to sit she will often cover up the eggs in the nest with twigs of heather, grass and bracken, and this must save many of them from the effects of frost. The Committee has had an exceptionally good opportunity of studying the effects of frost upon the eggs in the spring of 1908, when an extremely severe THE LIFE HISTORY OF THE GROUSE 11 frost was reported from every district of England, Scotland and AVales. For three days in the third week of April the thermometer registered from 10 to 27 degrees Fahrenheit. The Committee requested its local correspondents to make careful observations on the resulting damage, and the replies received are given in the form of an appendix/ Several interesting facts were brought to light — in general it was stated that the eifects of the frost had been disastrous : but when the evidence came to be analysed the proof seemed strangely incomplete, for very few reporters were able to state from personal observations that eggs laid before the frost had failed to hatch. On the other hand, several accurate observers reported that they had marked down eggs so frozen into the materials of the nest that it was not possible to lift them out or to separate them from each other, yet it was afterwards found that these eggs hatched out healthy chicks. On April 13th six Grouse eggs were found in a nest amongst heather when the temperature was 25 degrees of frost — and all six hatched out. On another occasion, when it happened that some Pheasant's eggs had been laid in a Grouse's nest, the Pheasant's eggs were the eggs which failed, while the Grouse's eggs were successfully hatched. Many correspondents went so far as to say that unless the frost was sufficiently severe to split the egg there was no danger of their fertility l)eing afl'ected, and of very many gamekeepers to whom the question was put very few could state that they had actually seen a Grouse's egg split by frost. Actual splitting of the eggs by frost does occur, but is exceedingly rare when the nest is in its customary position in heather. When placed in the open probably the eggs are liable to suffer just as Plover's eggs did in 1908, and an extra hard frost will sometimes split them. Even very scanty heather-growth retains the warmer air, and so shelters the nest and eggs from frost and winds. Moreover, if sitting has not begun the eggs are generally more or less buried in the material of the nest, so much so that it is impossible to count them unless they are disturbed. Enough has been said to emphasise the statement that the eggs of the Grouse are wonderfully tolerant of adverse weather conditions ; the fact is not sufficiently well recognised, and because occasional losses occur there is a tendency among gamekeepers to put down every failure of stock to some sharp frost or heavy snowfall in the month of April or May. They often do not inquire whether as a matter of fact any eggs were laid at the date when the frost occurred, they 1 J'idf vol. ii. Appendix I. 12 THE GROUSE IN HEALTH AND IN DISEASE seldom support their statement by pointing out nests deserted by the hen after being buried in the snow, they keep the plausible explanation ready for use if required, and if the stock after all proves to be up to the average, they feel secretly rather surprised, but say nothing about the adverse conditions in the breeding season, for the excuse may be required the following spring. Thus much valuable evidence is lost owing to the very natural desire of the game- keeper to prove himself the innocent victim of circumstances. Obviously, if the occasional snowstorms and moderate frosts of a normal April were really responsible for the damage so often attributed to them, it would follow that in a really inclement nesting season, such as occurred in 1908, the effects would have been disastrous throughout the length and breadth of the country. As a matter of fact, the bags in the autumn of that year, though unequal, were well up to, and in some places far above the average ; and even where a shortage of birds was reported the failure could often be traced to other causes than the unfavourable weather-conditions in the spring. While the evidence collected does not confirm the view that snow and frost in the nesting season are extensively destructive to the eggs of Grouse, there is some reason to believe that unfavourable weather, occurring immedi- tiouof ately before the date of laying, has an injurious effect upon the breeding by bad" powcTS of the parent birds. In the spring of 1908, for example, it was observed that on many moors birds which had paired, and were about to nest, became packed again on the arrival of frost and snow, and postponed their breeding operations until some time after the return of favourable conditions. The result was that they nested several weeks later than they would otherwise have done, and not only were their broods late, but the number of eggs laid was smaller than usual — sometimes averaging only four and five in a nest. The resulting smallness of the coveys was often accounted for by the hypothesis that several eggs in each nest had been destroyed by the frost in April ; but there was little direct evidence of this, and it seems equally reasonable to suppose that the power of egg production had been impaired by the enforced postpone- ment of nesting. The data are insufficient to establish this theory, but the point is worthy of a passing mention. It is certain that some of the eggs were lost owing to their having been dropped on the snow and not in a nest at all. After a certain stage of develop- ment the egg is laid wherever the bird happens to be. It is not uncommon to find eggs dropped in this accidental manner lying on the ground or on snow. THE LIFE HISTORY OF THE GROUSE 13 During the nesting season the hen leaves her nest for a short time in the morning and evening to feed and drink, and her presence in any particular part of a moor maybe known by the large "docker" droppings peculiar to a sitting bird. During the period of sitting the Grouse seems to be able to intermit its natural odour, and thus escape the notice of dogs and vermin. This point is noted by St John in "Wild Sports of the Highlands" when he states: -r . . . Loss of " It is a curious fact, but one which I have often observed, that dogs scent while frequently pass close to the nests of Grouse, Partridges and other game without scenting the hen bird as she sits on her eggs."^ Probably the cause of the loss of scent is that when the bird is sitting still the air does not get amongst the feathers and so the scent is retained. The same remark probably accounts for the fact that at midday, when the birds are resting, they are very difficult to find with dogs. The young Grouse are hatched after an incubation of twenty - three to twenty-four days, and leave the nest soon after they are freed from the shell. They are anxiously guarded by the parents, the hen being more attached to them than the cock, who, when they are disturbed, is the first to fly from danger, though it may be only for a short distance. The hen, on the other hand, will risk any danger rather than leave her brood — • be it only a single chicken or two. Often, too, like the Partridge and many other birds, she will feign a broken wing and flutter over the heather, apparently in a terribly damaged condition, until she has lured the intruder away from her brood. This fluttering action of the old bird should always be taken as a warning that the brood is young, that the squatting chicks are probably invisible, and that the danger of treading on them is great. It is most inadvisable to allow people who have flushed a cock or hen to walk about to see the size of a brood. It is at this stage that the weather conditions become important, for the young chicks are liable to many dangers. It is true that they do not suff"er from the cold, drizzly, sunless weather which destroys so many coveys of young Partridges, they are too hardy for that ; but heavy snow, hail, conditions or rain often takes its toll and leaves little trace behind beyond the young Grouse. fact that the coveys are found to be reduced in numbers when they come to the gun. Probably the half-grown chick runs more risk from weather 1 St John, "Wild Sports and Natural History of the Highlands," p. 29. London : John Murray, 1878. 14 THE GROUSE IN HEALTH AND IN DISEASE than when it is newly hatched, for its size prevents it from being completely covered by the hen when cold weather or heavy rain sets in. The period immediately following hatching, though so critical, is the period regarding which least is known. Few keepers like to disturb the ground at this time, and so the young bird's battle for life is fought unobserved, and only the closest and most patient observation would reveal the true conditions under which the chick's existence is passed. The young Grouse, even although they may be squatting within a few feet of the observer, are very difficult to find ; they seem to have the power of making themselves invisible at will, as they cunningly crouch by the side of a tuft of grass or heather, which often matches in colour the yellow, brown, and chestnut mottled down that covers their little bodies for the first few weeks. When at last a chick is discovered and lifted up in the hand its first " cheep " is the sio-nal for the others to scuttle away out of their places of concealment, or, if they are upwards of a month old, to make their effort at escape by a short flight, after which they are apparently incapable of a second attempt. It is astonishing how little accurate knowledge we have of the d'^ift'trTto principal dangers to which the young Grouse is exposed. yoiiSg 'Yhe practical gamekeeper admits that many dangers exist, and without weighing them too closely in the balance he does all he can to mitigate each of them. He knows, however, that in spite of his care there must be a certain percentage of losses from one cause or another, and it is with some anxiety that he proceeds to the moor towards the end of July to inspect the condition of the stock. The result is sometimes unexpected, often he finds the birds have safely survived the perils of youth, and that the moor is well stocked with unbroken coveys ; at other times he is perplexed to discover that the well-filled nests and successful hatchings are represented by a few abie°(S"" ragged broods of two or three birds, and a large number of barren SFyo^T'^^ pairs. He endeavours to account for the disappearance of the young I'Tds- birds, and in his search for a reason he eventually hits upon some- thincr which has some appearance of plausibility, and frequent repetition soon places theory in the realm of established fact. Mio'ration is one of the commonest theories, and is supported by the fact that few, if any, dead bodies are found on the ground. The migration Migration. ^Qp^j.jjjg presents some difiiculties, for the Grouse in its earlier stages is not bv nature a wanderer, and a brood is usually found, at all events THE LIFE HISTORY OF THE GROUSE 15 up to the end of July, not very far from where it was hatched out. Then, again, it is difficult to explain how on a large moor the young birds have departed before they are capable of sustained flight, especially if none of the neighbouring moors have received any noticeable addition to their stock. Lastly, it is per- missible to ask how is it that when the young birds emigrated to more congenial surroundings they omitted to take their parents with them ? Each of these points presents a difficulty, and the combination of them renders the migration theory untenable as an explanation for the absence of birds at any time up to the beginning of August.-' Another favourite theory is that all the young birds have been drowned, and if it so happens that there has been a severe thunderstorm in June the theory becomes a certainty — though not a single drowned '"' chick may have been found on the moor. There is no doubt that many young Grouse are destroyed by drowning, either as a result of being caught in a drain by a heavy shower, or by the flooding of low-lying ground. It is difficult to estimate the loss gi^eep occasioned by drowning in sheep drains, owing to the extreme '^^>"^- difficulty of detecting the small corpses in the swollen stream. One of the Committee's correspondents, a gamekeeper, who makes it a rule to inspect all the drains upon his ground several times during the nesting season, states that on one occasion only has he found a drowned chick in a drain. This evidence is, of course, only negative, and against it has to be reckoned the fact that many observers have spoken definitely as to the damage arising from this cause. On many moors the sheep drains have been scoured by floods into deep chasms, from which it would be difficult for the chick to emerge on the approach of danger, and any one who has seen a hill drain immediately after heavy rain, when it is running bank high in a miniature torrent, can picture the risk which might attend any attempt on the part of the mother bird to lead her brood over the obstacle. Much may be done to minimise this risk by forming little backwaters in the drains with shelving banks, by which the young Grouse may escape in time of danger. With regard to flooding, it is necessary to speak with more reserve. Flooding is a gradual process, and the instinct of self-preservation, which teaches the young Grouse to hide from his foes, will doubtless also teach him to retreat before the rising waters. In one case, however, flooding is a real menace, for if the ^ Vide vol. ii. Appendix G. 16 THE GROUSE IN HEALTH AND IN DISEASE nesting season is a dry one Grouse have been known to nest in very unsuitable places, such as the beds of burns and dried-up pools and water-courses — often with most disastrous results when the weather breaks. But, if there has been no rain, the drowning theory must be discarded, and its place is taken by the drought theory ; in other words, the fine, Drought. ^ ■' & J' ' ' ' dry, warm, sunny weather which is credited with producing a healthy stock in a good year is the cause of their wholesale destruction in a bad year. Nor do we know exactly what proportion of Grouse meet their fate from Vermin. Vermin ; that a certain number are killed by foxes, ravens, hoodie crows, stoats, weasels, and even gulls, may be admitted ; but when we come to apportion the blame we again find ourselves without sufficient evidence to amount to proof. The subject of vermin is dealt with more fully in another part of the Report.^ Occasionally it is found that old birds as well as young have disappeared, and when this happens it is customary to ascribe the cause to " Grouse Disease. . i i i • n c ■ • Disease amongst the adult birds, for it is well known that if a parent bird dies from disease or any other cause there is little chance of her brood surviving. At a very early stage of the Inquiry it became evident that the loss of young stock on a large scale had never hitherto been properly accounted for, and required further investigation by the Committee. The Committee believe they can oflfer a solution of this problem. During their Inquiry into the causes of mortality in Grouse they discovered a certain unicellular intestinal parasite, one of the Protozoa, a Coccidium, known as Eimeria avium, which in certain cases is most destructive to the young chick, but is rarely fatal to the adult bird ; this Coccidium is fully described in another chapter of this Report." The discovery of the disease caused by this pathogenic organism and known as Coccidiosis justifies the view that when there has been extensive mortality amongst the young stock which cannot be accounted for in any other way, it is almost certain that the chicks have met their fate by this infantile complaint.^ Coccidiosis as a disease of game birds and poultry is now being rapidly recognised in this country, and the disease is also being investigated in America. Still there remains the difiiculty that tbe dead bodies are not found in ' Vide chap. xx. pp. 443 et seq. ° Vide, cliaji. xi. pp. 235 et seq. ^ Vide also vol. ii. Appendix O. THE LIFE HISTORY OF THE GROUSE 17 any quantity ; it must be remembered, however, that the infant Grouse is a small object, and any one who has searched in vain in the heather for a full-grown bird which has fallen to his gun can realise the difficulty of finding a tiny chick upon a moor where the whole stock does not average more than a bird to several acres. Coccidiosis chiefly attacks the birds when they are very small ; the chicks die in the heather, the little carcasses are rarely found, and in a short time they disappear altogether for, even if they have not been devoured by vermin or removed by heat, wet, flies, maggots, or burying beetles, the small bones do not make lasting skeletons, and would not be discovered even if the moors were searched. In spite of difficulties the field observer and other members of the Com- mittee's scientific staff" have by diligent search been able to find a certain number of small dead chicks on the moors ; in almost every case the cause of death has been found to be Coccidiosis. Many other cases of Coccidiosis have been received for examination from various parts of Scotland and Yorkshire, and others have been obtained from the Committee's observation area in Surrey. Fortunately it is only in exceptional cases that we have to consider the question of a wholesale disappearance of the young stock from pathogenic causes. Under normal circumstances the Providence that watches over all Care of young things brings to maturity a large percentage of the birds in the that are hatched ; but Providence may be assisted, and the methods ofyoung by which it may be assisted are fully discussed in another part of this Report.' Suffice to say that in the earlier stages of the life of the Grouse the state of the moor is of great importance to the welfare of the birds. If the heather has been well burnt in a systematic manner the chicks have access to shelter in time of danger, yet are not lost in a wilderness of rank growth should a shepherd's dog scatter the brood in all directions ; vermin is kept down, and, most important of all, there is easy access to a plentiful supply of suitable food in the strips or patches of heather which are available in various stages of growth. The place above all others where we may be sure of finding a brood of young chicks, if there are any on the ground, is amongst rushes and long grass in the more swampy parts of the moor ; this is specially noticeable in very dry seasons. Whether the chicks seek these damp spots for the sake of shelter from the heat or in quest of insect life is not known. ' Vide chaps, xvii., xviii., xx. VOL. I. B 18 THE CxROUSE IN HEALTH AND IN DISEASE Flies, spiders, beetles, and greenish caterpillars about |-incli long, as well as slugs and chrysalides, have all been found in the crops of chicks. Fresh Calluna heather shoots, moss capsules, and tender blaeberry leaves young just Opened, if they are to be had, are also generally present ; and as the young birds grow older heather becomes more and more their staple food.' In a chick of a few days old, where the food consisted of small caterpillars, there was no grit to be seen in the gizzard ; and, in another, the muscles of that organ, with its toughened lining, seemed sufficient to crush the Grit found riii i -r>--i i r- ^ • ^ in young soit blaeberry shoots, riut it is the rule to nnd even m the youngest chick's gizzard a certain small quantity of fine quartz - grit and sand.^ When half-grown the crops of those examined contained a large percentage of heather, and the gizzards contained about half the amount of grit that is usually found in old birds, but in smaller fragments. Water, as supplied by streams and pools, does not appear to be necessary in the earlier stages where there is plenty of young heather ; insects, the succulent juices of the young heather shoots, and dew seem to provide all the moisture necessary. Broods are often hatched out far from any stream or pool, and they can generally be found within a few yards of the same spot till they are able to fly. On this point, as it affects the hand- rearing of Grouse, a well-known moor-owner writes : " I have never noticed that the young Grouse, when half-grown or older, require more water than what they pick up in the grass in wet weather, and what is sprinkled on the grass or heather at meal times, in dry weather. Old Grouse go to drink two or three times a day at most ; they seem to know how much is good for them ; whilst young Grouse, if allowed access to water, are apt, or almost certain, to drink too much, and scour. This, of course, refers to tame birds." Another of the Committee's correspondents (a gamekeeper on a large moor in central Perthshire) says : " Regarding water, I have known several broods fetched out 600 yards from the nearest water of any kind, in a dry season ; and they continued to thrive without water for at least three weeks after hatching." As the Grouse grows older, the parent birds relax their anxiety for the brood when disturbed, and, although they lie very close, the hen bird no longer flutters along the ground endeavouring to distract attention. Vide chap. iv. p. 73. - Ibid., p. 95. THE LIFE HISTORY OF THE GROUSE 1& Every keeper knows too well the danger that attends the needless disturbance of his beat at this time, especially in a high wind, which may carry the flushed birds hundreds of yards from their home. Instinct and the call of Dj^turb- the parents may guide them back ; but it is better that they should ^^^^°l^^ be kept quiet. It has been noticed that when a young brood are desirable, once upon the wing, in anything like a strong breeze, they appear to be unable to alight with safety ; at the end of the flight they dash headlong into the heather, or on to the ground, and frequently come to an untimely end. With the arrival of August 12th the Grouse comes into the glare of publicity, and there is little relating to his life history between this date and the end of the shooting season that is not known to the average sports- ^ . ... Grouse m man ; but even so there are variations in their habits in difl'erent the shoot- ing season, localities which still remain a mystery, and it may be worth while to mention some of these. While in the majority of cases the birds appear to be wild in proportion to their growth, this does not seem to be the only factor in the case, for in some districts on the west coast, notably in Skye, Grouse will sit close through- out the shooting season. It has been said that the reason for this is that in the districts in question birds of prey survive in larger numbers than elsewhere, and that the Grouse has not lost its instincts of self-preservation against the attack of its natural enemies. This may be true, but is not altogether convincing, for it is well known that to sit close is no protection against the Eagle, though it may be against the Falcon. The Grouse instinctively knows this, and the appearance of an Eagle, or even a Heron, is the signal for all those on the alert to fly in terror to some distant place of safety. Grouse feed oS" and on throughout the day ; but it is only in the evening that the crop retains the food which is then required for use during F^e^^i^g^ the night. Grouse. It is often stated that Grouse feed only in the evening, but the observations of the Committee make it quite clear that this is not the case. It may be observed in passing that at midday the Grouse appear to feed less, and towards evening far more than at any other time. Midday is given up to rest, and, in summer, to shelter from the heat of the sun, and the evening devoted to the complete filling of the crop with food for digestion during the night. Colquhoun in "The Moor and the Loch" refers to this habit as follows : " In sultry weather they lie quite still except at feeding time, and not 20 THE GROUSE IN HEALTH AND IN DISEASE having stirred perhaps for hours the dogs may come within a yard or two before winding them." ^ In the early part of the day and at dusk Grouse are found looking for grit, on the rough moor roads and tracks, or along the burn - sides, where every fresh spate washes down a new supply. The attraction presented to the Grouse by a suitable supply of grit is most marked. Good grit is to the Grouse what raisins are to Pheasants, and salt to Deer. They often fly long distances to obtain it, and in districts where it is scarce they will congregate in numbers along the railways and roads that traverse the moor, in order to avail themselves of the supply thus artificially introduced. Towards midday Grouse are generally found on the "tops" and higher grounds, and especially amongst broken moss-hags ; or, if the weather is very hot, they may be flushed from the burn-sides and shaded places ; in very rough weather they do not scorn the shelter afforded by a ledge of rock or bank of peat, and may then be best approached down wind. The best shooting is often got late in the afternoon on the low ground, to which the Grouse have descended to feed before "jugging," with crops crammed with heather shoots. When moving from one part of a moor to another Grouse usually fly low, and as their principal time for shifting their ground is in the early morning or at dusk they run a serious risk of death by collision with the wire sheep fences so common on many moors. This danger can be to a great extent averted by having all wire fences ■carefully " bushed" with bits of brushwood. Small branches of larch are best for this purpose, as they can be easily turned into the wires, and do not readily blow out — a fair-sized branch every 5 yards is suflicient. Spruce branches are also used. Telegraph wires are not so common on a moor as fences, and not nearly so dangerous, while the cost of protecting the birds from them by game-guards makes it hardly worth while to consider them. The Grouse, like the Domestic Fowl, the Pheasant, and the Partridge, is a "dusting" bird, and wherever a peaty or sandy bank has a sunny exposure a "' scrape," with a feather or two half embedded in the soil, is to ba seen. The fine particles of impalpable dust, by getting into the breathing apertures of the troublesome insects which are found on the birds, afi"ord the latter temporary 1 Colquhouu, "Tlie Moor and the Loch," p. 184. 6th Edition. Edinburgh: William Blackwood & Sons, 1884. THE LIFE HISTORY OF THE GROUSE 21 relief. Grouse also like to sun themselves on a warm bank or slab of rock — often resting with one wing extended. The practice of "becking" has been thus described in a note by Mr Alston in Dresser's "Birds of Europe" ' : "Early on frosty mornings the cocks are fond of perching on a knowe or hillock and uttering their clear-ringing e?--ecA-, <>Beck- kek-kek ! wuk, tmik, wuk. At such times they may often be seen to '°^"" rise perpendicularly in the air to a height of several feet, and then drop again on the same spot." "Becking" is fully described by the Rev. H. A. Macpherson in the Fur and Feather Series, where it is pointed out that the practice is in the nature of an amorous demonstration by the cock Grouse with the object of attracting his mate," and it may be compared to the peculiar antics adopted by the Blackcock and Capercailzie from a similar motive. " Becking," however, is not confined to the breeding season, indeed it is more usual during the autumn and winter months than in the spring. Mr Macpherson describes in a most interesting chapter the manner in which Grouse may be shot by taking advantage of this peculiar habit. Grouse, when fully grown, do not pass the night huddled together like Partridges, but "jug" singly amongst the heather, taking care not to be far apart. From the traces left in time of snow^ it is found that they Jugging. usually lie about a foot or two apart, so that a pack of a hundred may be contained within an area of a dozen square yards. In the words of a Highland gamekeeper : " Grouse glory in their ' hardiness,' " and it is almost incredible how little they are affected by wet, cold, and snow. It may indeed be said that so far as the adult Grouse is concerned it Hardiness matters not what the weather is so long as his food supply is not of Grouse, affected. They will never desert high ground for low ground merely on account of a heavy fall of snow, provided that there is sufficient wind to keep the exposed ridges clear, and thus give access to the heather ; and even if the whole qj,^ moor should be covered they will burrow in the soft snow to reach the heather underneath. It is quite common to come upon birds in holes a foot or two under the loose snow. It is only when the snow has become covered with a hard, icy crust that the Grouse begin to feel the pinch of hunger. On these occasions they may be seen in large packs following in the track of a herd of deer or a flock of sheep in order to take advantage of the broken surface. They ' " Birds of Europe," vol. vii. p. 168. Fur and Feather Series, " The Grouse," pp. 65-72. rouse ui snow. 22 THE GROUSE IN HEALTH AND IN DISEASE have even been known to eat the old unburnt stick heather which on all other occasions they reject as unfit for food ; but this is probably the last resource of the famine-stricken stock, and hardly justifies the practice of leaving a large amount of this unwholesome old heather as a food reserve in time of snow, for such a practice must greatly reduce the available supply of food at the critical period of early spring. A better practice is undoubtedly to burn all the more exposed ridges and knolls with careful discrimination, so that in whichever •direction the snow may drift there is a good chance that some good feeding heather will be left bare. It might be thought that where a heavy snowstorm occurs during the night there would be a risk of whole packs of Grouse being covered up and smothered by the drifts as the birds were jugging in a sheltered hollow. Sheep are often lost in large numbers by such misadventure, but Grouse never, for as they jug in the lee of a peat-hag or a moorland dyke they tread the snow under them as it falls, and are found next morning safely collected on the surface, though their fresh droppings several feet below show the level at which they began their night's repose. It has been said that Grouse often avail themselves of the shelter of woods and plantations in time of snow; but the evidence on the subject is most •contradictory. In some districts it has been found beneficial to plant trees as a shelter for Grouse ; in other districts, especially in the north of Scotland, they never use woods for shelter. It is generally believed that a hard winter with much snow is beneficial to the health of the stock in the following spring, and the reason commonly given is that the hard weather kills oti" the weaklings. There is no evidence to support this theory. Grouse are seldom found dead during the winter months, and when they are the cause can never be ascribed directly to the efiects of weather. If the belief that snow is beneficial is well founded, some other reason must be sought ; perhaps the fact that the weather has caused the stock to shift, and so introduced new blood where required, may have something to do with the improvement : more likely, however, the solution is found to be connected with the question of food supply. Ground which has been covered by snow for a period of several months provides better and more wholesome food than ground which has been heavily stocked, for when birds return in the spring they find the food supply still untouched by Grouse or Sheep, and the fact that it has been out of reach for so long has prevented it from being so heavily infected by the larvaj THE LIFE HISTORY OF THE GROUSE 23 of TricJiostrongylus as the lower moors which were crowded with Grouse throughout the winter. The melting of the snow may also have the effect of washing the Strongyle larvae out of the heather. If the birds are well matured by August 12th they often begin to "pack" after the first few days' shooting, and will not then readily lie to dogs. Packing may at times take place so early as to make shooting over dogs an „ , . •' \. J !^ D Packing. impossibility. On this account the poor results formerly obtained on most English moors led to the introduction of "driving." In Caithness and some other districts the Grouse, being more backward, do not pack except under exceptional conditions. This custom of packing is worthy of study, for it may be found to have a direct bearing upon the questions of disease, migration, interbreeding, and the preservation of the stock. In the first place, it may be stated that it is the young birds rather than the old birds that tend to form into packs in the earlier months of autumn, though the older birds will follow suit as the winter advances. Consequently, when packing first begins, it is the older birds that sufler the greatest loss in a day's Grouse driving, for they come up to the line of butts in twos and threes, and are " mopped up " to a bird, whereas the larger packs of younger birds merely yield a percentage of their numbers to swell the bag. To this cause may perhaps be ascribed some of the beneficial results which attend the intro- duction of driving on many moors. Another important fact connected with packing is the tendency of the stock to separate into sexes — there are hen packs and cock packs, or at least each pack contains a large majority of one sex. It has been noted that certain hills in a range of moorland are frequented by hen packs, others by cock packs. The normal time for packing is the autumn and winter months, and the more severe the weather the more marked is the tendency of the birds to form into lai'ge companies and flocks. Hens pack more readily than cocks ; the old cock does not appear to be of a sociable disposition, and often throughout the winter he will remain in solitary state, and only join the pack temporarily during a period of unusual storm. This tendency is often taken advantage of by those moor-owners who regard the old cocks as a menace to the health of their stock, and on many well-managed moors a rigorous crusade is carried on against the old single birds that frequent the bare tops, while their younger relatives occupy the lower ridges. 24 THE GROUSE IN HEALTH AND IN DISEASE During the winter months the advent of mild weather will often break up the packs for a while, and many cases have been reported of birds being scattered over the moor in pairs even in the months of November, December and January ; but with the return of wintry conditions their gregarious habits assert themselves even up to the commencement of the nesting season. The reason why Grouse should pack in winter has often been discussed. The most favourite explanation is that they combine with a view to obtaining Reason for ^'^'^^ ^^ ^i°^® ^^ Scarcity. Another theory is that, like manj^ other packing. ]3i].(Js and animals, the natural instinct of the Grouse is to congregate in flocks, and that this instinct is only departed from to meet the requirements of the breeding season. It is probable that various motives induce the birds to congregate in packs. Some of these motives may be briefly mentioned, (a) To get on to the high bare tops out of the wet — it is observed that Grouse are always more packed after wet weather. (6) To go down to feed on the cornfields ; Grouse are seldom found feeding singly on the stooks ; this may be due to the natural timidity of the wild bird, which makes it fear to resort to the unwonted feeding- ground unless supported by numbers. The same rule applies with even greater force to the case of birds leaving their own ground and wandering far afield in search of food ; such migrations never take place except in large packs, (c) Owing probably to the same cause. Grouse invarialily tend to pack after they have been much disturbed, especially by driving, on moors which for some reason have not been shot over for a season ; the birds do not pack until late in the year. (d) In dry weather small packs of two or three coveys are found at or near the springs even on August 12th. Undoubtedly, the most common cause of packing is scarcity of food. It has already been remarked that during the winter months the feeding area on every moor is restricted to those parts where the heather is of such a character as to resist the effects of frost and cold ; hence the birds tend to concentrate upon these food centres. The habit of packing is probably indirectly connected with the question of disease. If we admit that the congestion of a large number of birds upon small areas of moor is conducive to the deposit in dangerous numbers of the larval worms which cause disease on the favourite feeding - grounds of the birds, then it follows that the pack foi'mation is in itself a danger to the health of the stock. This view is supported by the fact that where packing is the exception rather than the rule, as in the west coast of Scotland, disease THE LIFE HISTORY OF THE GROUSE 25 is of rare occurrence. It is obviously impracticable to induce the Grouse to change this dangerous practice of congregating in packs ; but in another part of the Report suggestions are offered for minimising the risk of disease by distributing and increasing the areas to which the packs may resort for food.^ In autumn, where a moor is near arable land, the birds will often come to feed on the stubbles and corn stooks ; they sometimes come in hundreds, and from long distances. This is not, however, the universal rule, for in some districts Grouse feed ver}^ little upon the corn, and in some seasons they appear to frequent the arable land more than in others. It has often been observed that by improving the heather on a moor Grouse may be induced to feed less upon the stooks. The change is often accompanied by an improvement in the health of the stock, and this has given rise to the view that corn is an unwholesome diet for Grouse.' In very severe weather the Grouse leave the high grounds entirely, and remove in packs many miles to the lower moors where they can find "black ground," or to a hill plantation where they can pick up a bare sustenance seasonal in the shape of various seeds. When they are very hard pressed, as '"'S'-'^ wn- in the winter of 1894, they even flock to the turnip fields, and instances of their alighting on thorn hedges to pick the haws are recorded in the Field of that year. In Argyllshire they have been known to feed on birch twigs during the winter — settling on the trees to reach the woody buds. The subject of the migration of Grouse is one which has engaged the attention of many naturalists ; but there has been a tendency among observers to note only the abnormal cases, and from them to deduce a general rule. One great obstacle in the way of accurate observation is the difficulty of identifying the original point of departure of the wandering packs. In spite of the confident statements of gamekeepers that they can tell by the size and plumage of a bird that he has come from a certain district many miles away, it is more than probable that the newcomer has always had his habitation within a few miles of the neighbouring march, or even that he has never left his home, but has disguised himself by a sudden moult. In some districts undoubtedly the birds shift annually in vast packs from the high ground to the lower moors, and return again in the spring to breed. On rare occasions migration takes place upon a much more serious scale, ' Vide cliap. xvii. p. 392. ^ Vide cliap. viii. pp. 178-180. 26 THE GROUSE IN HEALTH AND IN DISEASE when the whole Grouse population of a district, driven by hunger, rises in huge packs and works its way southward in search of food ; this never happens Wholesale ^^^sss a heavy undrifted snowfall has been followed by a hard frost, migration, -^yhereby a whole district is covered with an impenetrable sheet of frozen snow, thus cutting off all access to the heather. Such wholesale migrations often result in a complete loss of the stock, for the birds appear to lose their bearings, and though they may sometimes find a haven on some distant moor, where weather conditions are more propitious, several cases have been recorded of the packs being seen on the low ground 20 or 30 miles from the nearest hill, or even flying out to sea, whence presumably they never return. In the case of normal annual migrations many opportunities have fl^^ht'of"^ occurred for observing the power of flight of the Grouse. The foUow- Grouse. ^jjg passage may be quoted from Macpherson in the Fur and Feather Series : ^ " When snow and sleet have driven them down from the hills they will then fly long distances. It is not at all unusual for Red Grouse to cross the Solway Firth at a point where the estuary measures two miles in breadth, and I have known them fly longer distances. They often cross the valley of the Tees, flying about a mile from one hillside to another." .\nd he quotes Millais, who says : " I have twice seen Grouse on the wing when they were crossing the ' Bring,' a wide channel which separates the islands of Hoy and Pomona, Orkneys. The fishermen told me this distance . . . was quite four miles across, and the birds must have come at least another mile on the Pomona side from the point where they left the moor."" In Millais' "Game Birds" it is stated that Grouse have been observed flying from Thurso to Hoy. a distance of over 11 miles.^ The following instances are vouched for by the Committee's own correspondents. A gentleman in Banflshire, writing in January 1907, says: "Packs of Grouse are continually flying across the valley during stormy weather, some 5 or 6 miles between moors " : while in Cumnock, in Ayrshire, there are "two ranges of hills divided by a valley about 2 miles wide, with a moss lying in between. In the pairing season Grouse often fly at a considerable height over the valley between the hills." Even during a Grouse drive a pack has been observed to leave the hill where it had been flushed, and not to rest until it had reached another moor 6 miles ' Fur and Feather Series, "The Grouse,'' p. 36. • MiHais, "Game Birds and Shooting Sketches," p. 5.3. London : iienry Sotheran & Co., 1892. ^ .Millais, "Natural History of British Game Birds," p. ")4. London : Longmans, Green & Co., 1909. THE LIFE HISTORY OF THE C4R0USE 27 distant. Longer flights are more difiicult to authenticate ; Harvie Brown states that "in the severe winter of 1878-1879, a pack of Grouse was seen crossing the Moray Firth in December, making for the Banfi" coast, as we were informed at the time by Sherift" Mackenzie of Tain. Much snow was lying at the time in East Sutherland and Caithness";^ and Macpherson (loc. cit.) says also that " The Rev. M. A. Mathew records that a solitary Red Grouse was shot by Mr C. Edwards on the Mendips near Wrington, Somerset, in September 1885, and this he suggests must have crossed over the Bristol Channel, migrating from Breconshire." ' Other records in " Birds of Essex," are quoted in Macpherson. ^ We are indebted to the same writer for the following information upon the general habits of migration among Grouse. "Their principal time for shifting about is in the evening after feeding, and again after ' becking ' in the morning. But they are particularly restless on many moors about the end of September and in October, especially the female birds, and the first strong gale brings many of them oif the hilltops, looking for more sheltered and genial situations. " Birds of both sexes will fly a long distance to a patch of black heather during a prevalence of severe frost and heavy snow, but the hens shift about in packs more irregularly than their male companions, and they are less partial to the high grounds, but seek the lower portions of the moor, and such as are most screened from the east winds. Grouse netters say that in fine open weather the birds fly very long distances when shifting about the hills."'' Observations upon the wandering habits of individual Grouse have also been made where some peculiarity in the bird has made identification possible. An Ayrshire gamekeeper has told the Committee's field observer of a pure white Grouse which was seen and freely shot at on Glencairn and Upper Cree. It then disappeared, and was seen and shot at many times on a shooting 12 miles away. It was eventually killed by a gamekeeper 9 miles away from either of these moors, and now forms a stuff'ed specimen in a case in his cottage. All this happened in one season. The question of the annual movements and migrations of Grouse are important as a guide to the best methods to be adopted for the regulation of ' Harvie Brown & Buckley's "Vertebrate Fauna of the Moray Basin" vol. ii. p. 152. Edinburgh : David Douglas, 1895. " Fur aud Feather Series, "The Grouse," p. 37. = Ibid., p. 39. * Ibid., p. 77. 28 THE GROUSE IN HEALTH AND IN DISEASE stock. The fact that Grouse annually shift from place to place over a wide area forces one to the conclusion that co-operation is necessary rather than individual effort. For the same reason it is doubtful whether the benefit of introducing fresh blood (either in the form of eggs or of living birds) is confined to the moor on which the fresh blood is introduced. This remark would not, of course, apply to an isolated moor, or one in which for any reason the shifting habits of the birds are not fully developed. Various opinions have been expressed as to the age which a Grouse can attain, and a few observations on the subject may be quoted. On a York- Age of shire moor a cock Grouse, which was recognisable owing to its having Grouse. ^ broken leg which stuck out permanently at right angles, was known to have lived for nine years in a wild state. An Ayrshire gamekeeper, one of the Committee's correspondents, can vouch for a Blackcock living twelve years, and is of opinion that Grouse live as long. Another correspondent, a Forfarshire gamekeeper, is sure that many of the old cocks on the tops are ten years old, and if appearance goes for anything the black old cocks so often killed on the high tops of many moors must have reached a not less patriarchal age. In view of the many dangers to which they are exposed the wild Grouse seldom gets the chance of dying of old age, and the duration of its life depends more on the severity of the shooting and the numbers of vermin than upon the bird's own longevity. Observations on Grouse in captivity tend to support the view that they can live to a considerable age. Unfortunately, in every case reported to the Committee where a tame Grouse has reached the age of ten or twelve years the bird has died an accidental death. CHAPTER Iir THE CHANGES OF PLUMAGE IN THE RED GROUSE IN HEALTH AND IN DISEASE By Edtvard A. Wilson Part I. — Plumage Changes of the Cock Grouse When a large number of skins of the cock Grouse are arranged together, side by side, according to the month in which the birds were killed, it will be found that, even taking into account the diflerences of well-marked local variations in plumage, the series can readily be divided into two very distinct sets. There is first a very marked uniformity in the plumage of the cock birds killed from the middle of November to the end of June ; and likewise amongst those killed from the end of June to the middle changes of of November. These two periods, November to June and June to November, mark the two seasonal changes of plumage in the cock Grouse. The first is a plumage ^vorn throughout the ivinter, as well as during the courting and breeding season of the sjmng. The second is a plumage ivorn throughout the late summer and early autumn. It is necessary to lay stress upon this general broad division of the cock Grouse's plumage, and if a large number of skins can be arranged as suggested the time at which the Grouse has definitely changed from the one plumage to the other cannot possibly be overlooked. The birds obtained at the end of May are definitely in the darker and redder winter plumage, and those procured at the end of June are definitely in the paler and more bufi'-coloured summer plumage ; those killed at the beginning of October are still partly in the paler summer plumage, and by the end of November all are in the darker winter plumage. ^ Reprinted from tlie Proceedings of the Zoological Society of London, 1910, 29 30 THE GROUSE IN HEALTH AND IN DISEASE It must, however, be added, that there is hardly a month in the whole year, or a Grouse skin in a collection of many hundreds covering every month of the year, in which one plumage only can be found unmixed with the other. This fact accounts largely for the misunderstanding which at one time existed, but which has now, we hope, been satisfactorily settled, in respect of the whole vexed question of moult and plumage changes in the Eed Grouse, and their proper interpretation. Without referring in detail to the points upon which differences of opinion have before now arisen, it may be shown that much misunderstanding upon Keasons for t^is difficult subject is based upon a different rendering of facts into mSinder- '^'ords, facts which were recognised and perfectly well explained by standing, jyjj. Qgilvic-Grant in 1893.' Both he and Mr Millais have made the subject of plumage changes in the game-birds, and especially in the Grouse, a special study, and it must be admitted that there are very few points upon which they have touched which seem to require further explanation and still fewer points, if any, which can be brought to light for the first time in connection with the plumage changes of the Red Grouse. A monograph on the Red Grouse, such as the Report of the Grouse Disease Inquiry, would, however, be obviously incomplete without an account of the plumage changes of the bird itself ; and it so happens that during the six years of the Grouse Disease Inquiry's existence the collection of some six hundred Red Grouse skins, representing every age, phase, and change of plumage in that bird, has given a unique opportunity for an independent revision of the work already done— an oppor- tunity such as has never occurred before in the study of any single species of Effect of British bird for observing the effect of disease upon moult and feather piuml'a-e" growth. So it happens that although the work as it stands has been changes. g^ nearly completed by the labours of the two ornithologists already mentioned, there are still points of interest to which attention may be drawn, especially in connection with the marked effect which parasitism and other wasting diseases have upon the moult and growth of feathers, and it is to this influence of disease that attention will be particularly drawn in the present paper. It is important to note the extraordinary irregularities which so commonly occur in the plumage of the Red Grouse owing to disease, whereby the ' (1) "Annals and Magazine of Natural History" (G), xii., July 1893, pp. 62-G5 ; (2) "Catalogue of the Birds in the British Museum," vol. xxii. November 1893, pp. 36-38; (3) "Annals of Scottish Natural History," July 1894, pp. 129-140, PI. v. and vi. PLUMAGE CHANGES OF THE COCK GROUSE 31 deferred moult becomes in some years almost the rule, and the rule of health becomes almost the exception. It is a very difficult matter, Effects of indeed, for any one who has not had the opportunity of examining 'i'^^'^^^- an extensive series of Grouse skins, in disease as well as in health, and cover- ing every month of the year, to come to any true conclusion about the moult. Diseased conditions often entirely mask the normal plumage changes from time to time, and it is far more important to realise this than to examine thousands of more or less healthy birds shot in the ordinary course of events in the shooting season. A study of abnormal plumage changes in diseased Grouse is essential if the discrepancies which arise in the moult of what are often wrongly considered normal birds, are ever to be explained. Once this point is grasped the question becomes much simpler, and it is because the Grouse Disease Committee has had such ample opportunity for studying both sides of the question that it has been deemed necessary to enter into these plumage changes at such length. It is almost incredible that a moult should be deferred from one season to another, or even to a third, and that the right plumage should eventually be produced if the bird, by means of good food and good weather, is at 1 i- 1 11 Effect on last enabled to recover its health and grow any new feathers at all. feet and I • • • 1 1 legs. it IS interesting, and to some people, such as sportsmen and game- keepers, even useful to know that bare featherless legs and feet, which have so long been considered a sure sign of disease in the Red Grouse, may, in certain months of the year, be a natural accompaniment of really good health, while thickly feathered legs in the same month are a sure sign of deferred moult and of sickness. It is only when the proper season for the moult of the leg and foot - feathering is completely understood that we begin to understand the reason for attaching an unfavourable prognosis to heavy leg-feathering when the legs should have been featherless, and an equally favourable prognosis to bare legs when the legs should certainly have been bare (PI. xiii., Figs. 1-2). To return, however, to the two plumages of the healthy cock Grouse. They are distinguished by Mr Ogilvie-Grant as the autumn plumage and the winter- siimmer plumage, and he says further that the cock "has no distinct summer plumage."^ It is perfectly easy to see what is meant by this, and also b}^ the statement which follows, that the cock "retains the winter plumage throughout the breeding season." ^ " Handbook to the Game Birds," p. 28. (Allen's Naturalists' Library). London : W. H. Allen & Co., Ltd., 1895. 32 THE GROUSE IN HEALTH AND IN DISEASE Mr Millais also, in speaking of the cock Grouse, makes use of the expression autumn plumage which, he saj's, appears late in June ; and he adds that the autumn plumage, together with the " spring feathers" (or what Mr Ogilvie- Grant considers the first beginning of the autumn jilumage on the Grouse's neck), remain till the main moult in August and September. Mr Millais also makes the following statement, which appears to be based on a misinterpretation. He says : " as a matter of fact the male Grouse sheds in September and August a plumage which is a mixture of its winter, spring, and eclipse feathers." ' These so-called " spring " and " eclipse " feathers are no doubt, as Mr Ogilvie- Grant holds, the commencement of the plumage which is completed gradually during the summer months, and which he has described as the autumn plumage. It is naturally a little misleading to find the autumn plumage beginning to appear in early summer, but so long as the term is understood to mean the paler, more buff-coloured plumage with bolder bars of black, which begins to appear first on the neck of the cock at the end of May or early in June, and is eventually cast for the winter plumage in October, there need be no real misunderstanding. That feathers of the previous winter plumage should be mentioned in speaking of the moult of this autumn plumage is also quite intelligible, since the old winter plumage of the breast and abdomen is being quickly shed and replaced by a similar new winter plumage at the time when the autumn plumage on the rest of the body is being cast. There are in addition very frequently a few feathers of the copper-red j^lumage on the chin really belonging to and remain- ing over from the previous winter plumage. Instead of going into further details, however, with regard to the two moults and plumages of the cock Grouse, it will l)e simpler at this point to take its plumage changes in detail, successively month by month, explaining as nearly as possible what can be gathered from the examination of a series of skins such as has been brought together by the Committee, including as it does a great number of specimens in all stages of disease as well as in health. These illustrate every month of the year and most of the local variations to be found in England, Scotland, and Ireland ; and there are a suflicient number of sick as well as healthy birds to show the very great influence that disease has in altering the individual capacity for feather growth. Unless this effect, which results as a rule in the Red Grouse from excessive parasitism, is ' In lit., "British Birds," for Ajiril 1910, vol. iii. p. 382. London : Witlierley & Co. PLUMAGE CHANGES OF THE COCK GROUSE 35 fully recognised, there will always be misunderstandings upon the moult of this bird, for almost every Grouse in the country is to some extent infested with parasitic worms, and there are years when irregularity of moult is the rule rather than the exception. Moreover, it so hap^aens that in autumn, when birds are being shot in large numbers, the survivors of the two worst months of the year for "Grouse Disease" mortality, that is, the survivors of Ma)^ and June, are all convalescing ; but they are convalescing with their plumage changes all retarded and put completely out of order and routine. In this way it is possible in September to kill two birds on the same day, both of which have the chestnut- coloured feathers of the winter plumage on the chin and throat ; but upon examination it may be seen that in one bird the edges of these feathers are frayed and worn and the colour faded, showing that they have survived from the p?'ei;iOM5 winter plumage ; whereas in the other bird they are hardly free of the scaly sheaths in which they grew, and are really precocious feathers of the coming winter plumage. This is only one of the many traps which result from the deleterious influence which disease exerts upon a bird's capacity for feather growth and replacement, and so upon the regularity of its moult. There is another point to which attention must be drawn before entering upon a systematic description of the monthly changes of feather in the cock Grouse. It is as to whether the autumn plumage of the cock can ..Eclipse" be correctly described as an "eclipse" plumage, comparable as it pi"™^ge. obviously is in character with the spring breeding plumage in the hen, but appearing just two months later and after the breeding season. In each sex the general change from winter to summer may be described as a change from a more richly pigmented, darker, black and chestnut, or rufous-chestnut plumage with rather fine transverse black markings, sometimes almost vermi- culate in character, to a less richly pigmented, paler, buff or rufous-bufi" or tawny- buff" plumage with characteristically broad black bars and transverse markings. In each sex, moreover, the characteristic buff" and black broad-banded summer plumage is given its special appearance on the dorsal aspect by the growth of feathers with large black centres and a few buff" or tawny- buff" subterminal bars of considerable width, and a terminal border or spot of the palest buff", which is a very conspicuous feature on the back of most hens, and often only less conspicuous in the cock. In the cock, however, this plumage appears just two months later, and is less beautifully developed than in the hen. VOL. I. c 34 THE GROUSE IN HEALTH AND IN DISEASE There is without doubt a general broad resemblance, firstly between the cock and the hen Grouse when the former is in its "winter plumage" and the latter in its " autumn plumage " ; and, secondly, between the cock and the hen Grouse when the former is in its "autumn plumage" and the latter in its "spring plumage." The perplexing fact is that these general resemblances are not synchronous Cock and ^^ ^hc two scxes, a peculiarity first observed by Mr Ogilvie-Grant, atdifferent ^°^' ^^ already pointed out, there is an interval of two months seasons. between the moult of the cock and hen. Again, it might reasonably be expected that, as the Ptarmigan and the Scandinavian Willow Grouse have not two plumages in the year, but three, some suggestion of the third plumage might be forthcoming in the Red Grouse. But the Red Grouse has only two moults. Mr Ogilvie-Grant, how- ever, explains the position by saying that the bufi" and black plumage of the hen Grouse answers to the spring plumage of the hen Ptarmigan, while the buff and black plumage of the cock Grouse answers to the autumn plumage of the cock Ptarmigan. The grounds for this opinion will be considered later in the light of the possible effect which continued disease may have in permanently altering the season of the moult. Beginning now with the cock Red Grouse in January, and taking its appearance from the ventral aspect first, the uniformity of the series Grouse in is a Very conspicuous feature. Every healthy bird is chestnut or rufous-chestnut and black, with fine, almost vermiculate black cross- lines over it. Even in the blackest birds the throat and fore - neck are always of a rich copper-red colour, with very little or no black edging at the borders •of the feathers, which are usually barred with black only on the actual chin. Here there may be also more or less of white tippiugs, even to the formation -of two white moustachios leading downwards from the gape, sometimes an inch in length. This may be a feature either of the black type or of the red '(PI. n. and ill.). In some very red and black Red Grouse the abdominal feathers are also freely and broadly tipped with white ; and this may sometimes he seen even on the feathers of the upper parts (PI. iv.) The legs and feet are thickly feathered, and are white, or white with brownish barring. The 1 The whole chapter deals with the Red Grouse (Lufiopus scoticus Lath.). The terms "black Red Giouse" and "buff-spotted or white-spotted Red Grouse" must not be confused with similar terms for other species of Grouse. PI. //. (P.Z.S. 1910. P/. Z.V.V/.V. ) Andre & Sleiuh. Ltd MALE GROUSE, BLACK TYPE, IN FULL WINTER-PLUMAGE. PL III. (P.Z.S. 1910. PI. LXXX^ Andre & Sleigh, Ltd. MALE GROUSE, RED TYPE, IN FULL WINTER-PLUMAGE, PI. IV. (P.Z.S. 1910. PI. /.\A'.V/.) Aadri: & tilei^b, Ltd. MALE GROUSE. WHITE-SPOTTED BIRD OF THE RED TYPE. PL V. (P.Z.S. 1910. PL Z.V.VA7/,) Andre A Slcij^h. L:d. MALE GROUSE REO TYPE, IN FULL WINTER-PLUMAGE WITH A FEW BLACK CENTERED FEATHERS OF THE PREVIOUS AUTUMN-PLUMAGE. PLUMAGE CHANGES OF THE COCK GROUSE 35 claws are often in this month very long and strong. Occasionally a pale bleached feather of the preceding "autumn plumage" is to be found on the Hanks, middle of the breast or neck, and may be recognised by its frayed edges; and occasionally (e.g., No. 539), in a very backward bird, there may be many such worn and faded feathers on the chest and flanks, but such a case is invariably the result of sickness. On the dorsal side there is again, broadly speaking, a general uniformity of chestnut, bright or dark, or of blackish feathers, with fine black transverse markings ; but in almost every bird there may be found a considerable number of the old black - centred "autumn plumage" feathers remaining, with their frayed and faded edges of whitish-buff (PI. v.). On the lower back and rump the more worn and faded feathers predominate. The primary and secondary quills are all complete, and are but a few months old, having been renewed between June and August ; and the same may be said of the rectrices. The following points in the cock Grouse of January are characteristic. (1.) The rich copper-red, generally unbarred feathers of the throat and fore-neck (PI. xvi., Figs. 3 and 4). (2.) The fine barring of the chestnut, dark rufous-chestnut, or blackish- brown of the back, with the scattered black-centred feathers of the last " autumn plumage." (3.) The thick, white feathering of the feet and legs, which .soon becomes blackened and worn by the "burrens" or "colons," the charred stalks of old burned heather. (4.) The perfect flight-feathers of the wings and tail. (5.) The very large claws. In February the cock Grouse is still in the darker winter plumage. Young, sheathed and growing broad - barred feathers, the remains of the "winter plumage," may still occasionally be found on the hind- ^ "^^^^' neck, nape, and head in backward birds. In March the cock Grouse normally shows no change ; but towards the end of the month in exceptional instances individual birds may be found with a few precocious feathers of the autumn plumage making their appearance on the back of the head and neck. These are very probably feathers irregularly developed to take the place of those which have been lost during encounters with other males. In April the cock Grouse still shows no change. In this month there are ae THE GROUSE IN HEALTH AND IN DISEASE often greatly increased opportunities for the addition of skins to a collection, because it happens to be a month of very high mortality from " disease." The birds are found and can be collected not only l)y the keepers who are out early in the month in search of fox-earths, and who are generally also burning heather about this time, but also later by the shepherds who are constantly ranging the moor in the lambing time. During the last five years there has been a great accession of Grouse skins to the Inquiry's collection in March with a very large proportion of males badly diseased, and comparatively few birds in perfect health. Therefore, in the series of skins of cock birds representing the month of April, the great majority are very backward. Healthy birds have still the old, rich, red, copper - coloured throat of the winter plumage, and fresh - looking "autumn" feathers round the neck, upper back, and mantle, while the winter and old autumn plumage of the rump and back is bleached and faded. The backward birds are easily picked out, as they have not yet assumed their " winter " plumage, and are still mostly clad in old, worn autumn plumage of the previous year. If an April bird has newly and thickly feathered legs and feet, it means, almost certainly, that the "winter" plumage has been put on very late. The healthy Grouse should now be moulting the feathers of the feet and legs, so that bareness or lack of feathers becomes in them a sign of health in April, and thickly feathered legs a sign of sickness ; this is the precise contrary of what has almost become proverbial on the moor, that bare legs indicate disease ; though for the later autumn months the saying is quite true. In May the preponderance of cock birds found dead, and therefore of skins of cock birds in the May collection showing belated moult, is again a large one. The healthy cock is still in his much-worn winter plumage, but on the head and neck some feathers of the new autumn plumage are beginning to make their appearance (PI. vi. and vii.). In June as a rule, the mortality amongst adult birds, due to Strongy- losis, is coming to an end ; but for the young chicks June and July are often fatal months owing to Coccidiosis. Late in June the healthv June. ° . . . - cock Grouse can at last be said to have changed into his com- plete "autumn plumage." The winter plumage persists only on the abdomen and lower breast, on the actual chin which is blackish with a few white spots, and on the throat, where a few red feathers still remain. The moulting of the quills and tail feathers commences towards the end PI. VI. (P.Z.S. 1910. PI. LAXX///.') AnUre A: Slt^it^h, Ltd. MALE GROUSE SHOWING MARKED BEGINNING OF THE AUTUMN-PLUMAGE ON HEAD AND NECK. PI. VII. (P.Z.S. 1910. PI. Z.V.V.V/K. ) Andre \- Sleiyh. Ltd. MALE GROUSE CHANGING FROM WINTER- TO AUTUMN-PLUMAGE. PLUMAGE CHANGES OF THE COCK GROUSE 37 of the month. The rump and back are now completely covered with new black - centred feathers carrying broad - barred buft" and black bands, and a few have a whitish terminal spot, similar to that found in the female The head and neck, breast and throat, are now clothed in broad - barred buff and black feathers, quite distinct from the more chestnut and more finely black-marked plumage of the winter. It is impossible on seeing a series of the birds showing this distinctive change to avoid noticing how closely this autumn plumage of the cock approximates to the nesting plumage of the hen, and yet it is wrong to think and to speak of this "autumn" plumage as an "eclipse" plumage, for it has arrived in the cock just two months later than it is normally due in the hen — far too late to be a breeding plumage. It appears almost as though the pathological postponement of the moult, a postponement which is, after all, nothing but a sign and a symptom of disease, has gradually developed into a normal habit in the life of Possible the bird, and one is led to think that this habitual disability in the "josHone- cock Grouse, which results from Strongylosis during the nesting, '"*^°*- courting, and breeding season (a disability which causes the death of about eight cocks to every hen in April and in May), may have caused the altera- tion in the season of the moult, simply because the vis vitce of the cock bird, insuflicient as we now know it to be at the close of winter for the ordinary calls of reproduction, would be still more disastrously insufficient if preceded by an early moult. At the present time the cock undoubtedly breeds in the winter plumage, without any further acquisition of new feathers, and, as has recently been pointed out by Mr Ogilvie-Grant, what have been regarded by Mr Millais as new "spring feathers" on the neck are in fact the old autumn feathers, which on that part of the body do not become worn and faded. That any feather of the Grouse, either in the cock or in the hen, was ever altered as to its pigment either in pattern, or in tone, or in chano-ein any other character, when once it had completed growth and had j™'"ob-*^ been cut off from the circulation, is at present an assumption which '^^'''' is not well supported by the physiology of feather growth. Metchnikoff's observation upon the migration of leucocytes into hair and their action in removing pigment cannot for one moment be adduced as conclusive proof that the same thing may happen in the case of a full-grown feather. While the circulation is active in the feather shaft, and for as long 38 THE GROUSE IN HEALTH AND IN DISEASE and ia so far as it continues, pigmentation may be altered, but once the circulation has ceased beyond the entrance to the base of the shaft, and once that the feather, although still attached to the epidermis, is cut oft' from the circulation in the deeper living layer of the skin, then the feather is no more likely or able to change the pigment which is responsible for its pattern or its colour than would be the same feather had it been plucked out and kept entirely separate from the bird. Once the feather is full grown, and the circulation in it stopped, there is no reason to believe that any thing can alter it save sunlight and water, and oil supplied as an external unguent from the oil gland. That appearances are most deceptive in this respect must be allowed. Feathers may be collected from the flanks of hen Grouse which show every possible graduation Pi menta- between the almost vermiculate flank feather indicating the perfect tion. winter plumage, and the broad-barred breeding-season flank feather of the summer hen. But it is very much more probable that the growing period of these ambiguous or intermediate feathers is one of great susceptibility to outside conditions, as we know to be the case in respect of the metal lolic processes which are taking place within the hen bird at the time. Pigment is indis- putably a product of tissue metabolism. It is often probably a mere waste product, but it appears at times to serve a special function notwithstanding. It is also certain that pigment is a production whose appearance, or failure to appear, is open to considerable vicissitudes in consequence of small recognised changes in physiological condition, and of some less easily recognised changes in the general metabolism of the body. In the hen Grouse during the breeding season we know that pigment production is very actively at work, for we know that a very large amount is being produced for excretion in the pigment glands of the lower part of the oviduct. This pigment, moreover, is precisely of the shade and colour which is characteristic, not of the breeding plumage, but of the winter dress of the hen and the cock Red Grouse. It is normally deposited in al)undance on every egg, but on the other hand it may abnormally fail to be deposited or even produced at all, not only in the eggs in the oviduct, but in the circulating blood of the bird's whole system. Thus the feathers, instead of becoming bufl' or brown, reddish or even Ijlack as they proceed in growth, may be any intermediate paler shade of bufl', or even white, a character which is due generally to the complete absence of all pigment granules. The place of PLUMAGE CHANGES OF THE COCK GROUSE 39 the pigment in sucli feathers is probably taken by shining air globules, as it is in the hair and feathers of the majority of white animals and birds. It is thus easier to believe that a sudden check, either by a change of temperature, or by wet and cold, or by want of sunshine, or by change ia food, has for the time so far affected the tissue metabolism of the bird that a feather which began to grow upon a circulation lacking pigment particles, and which was therefore originally planned for the paler plumage, may, by a sudden increase in the metabolism of the bird, and so in the output of waste products to the blood, be completed as a feather of the more deeply pigmented plumage, thus producing a feather with the characters- of both. This is a plausible explanation, but is still open to some doubt, for the difierence between the broad - banded bufl' and black flaukfeather of the nesting hen, and the dark red-brown finely cross-lined feather of the same bird in winter, is obviously greater as regards pigment distribution than as regards the actual quantity of pigment deposited in the feathers. If there are, as has been held, distinct pigments, such, for example, as buft', black, and orange-red, in the various colour-tones of the Red Grouse, it becomes easier to see that the loss of the red pigment, which is utilised for the eggs, leaves the buff and the black in greater quantity for the nesting season plumage. In the winter all three would once more be available. The fat of the nesting hen is distinctly rich in colour, but in no case that we have seen has it amounted to the orange-coloured fat which is often seen in overfed Pheasants, and quite commonly in Gulls and Terns- which have been feeding on red crustaceans. In these birds the orange-red fat or oil, tints not merely the fat beneath the skin, but even the white feathers of the breast and body often present a very beautiful rosy flush. The whole question of pigment production and pigment distribution, intimately connected as it is with the question of the excretion of waste products and the deposition of fat, both in health and in disease, has not reached a stage which admits of dogmatic statement upon the subject of pattern change in feathers without moult. One recognised method of changing a colour-pattern in feathers without moult is to be seen in the male of the familiar House Sparrow, which produces a handsome jet-black cravat in the breeding season, where before was a nondescript greyish throat ; and this it does by the simple process of 40 THE GROUSE IN HEALTH AND IN DISEASE shedding the grey ends of the feathers, leaving the blacker parts exposed. This method is common among birds, but the Red Grouse has been credited with changing in situ the colour and pattern of the flank feathers. Now, with still less reason as it seems, the cock bird has been credited by Mr Millais with achieving his summer or breeding plumage "for the most part by repig- mentation and pattern change of most of the winter feathers below the neck." ^ This view cannot be upheld physiologically, and there is much to support the contention that the feathers which are believed to effect this change of pattern without moult are actually new growing feathers. This can readily be shown by the demonstration of their unshed sheaths. The misleading birds are asfain in this case the cocks which have been too sick to shed the previous "autumn plumage," and so are still struggling, with increasing success as the food improves, to produce a " winter plumage," which they should, and would in health, liave achieved in October. That the cock bird should moult the feathers of the legs and feet between March 30th and June 17th is no loncrer difficult to understand when the prevalence of Strongylosis is fully grasped. No bird is safe from the nematode infestment, and we are led to think that the majority of cock birds are so badly infested that they are forced to defer the autumn moult which should precede that of the previous winter. It is therefore obvious that between March and June there will be every stage of good or bad leg and foot-feathering between the newly acquired thick, white winter stocking of the sick cock, and the naked featherless clean moulted leg and foot of the really healthy male bird in June. In July, again, the healthy cock bird will be found beginning to produce white feather tips over the legs and feet. In July the general appearance of the healthy cock is much lighter in colour-tone, and much more broken and mottled in pattern - character than that of the same bird in the winter. The claws are in many cases now ready to be shed, and the primaries, secondaries, and tail feathers are in moult. Some six or eight new clean- grown primaries are often to be found in July, and the long tail coverts are broad-barred buff" and black. In August the cock Grouse has, of course, the appearance of full summer or autumn plumage, but it requires very little examination to see that he has already begun to put on feathers of the winter plumage. ' " Natural History of British Game Birds," p. 40. PLUMAGE CHANGES OF THE COCK GROUSE 41 He now rapidly sheds the old feathers of the last winter's plumage which remained throughout the summer upon his breast and abdomen, and replaces them with the exceedingly handsome narrow cross-barred red or brown or blackish feathers of the coming winter plumage. There is no second moult or replacement of these feathers of the breast and abdomen in the cock. Once in the year is enough for this special area, and the feathers that " carry through " are wholly of the winter plumage. Thej^ are often broadly tipped with white. The chin feathers which survived with those of the breast and abdomen are now also replaced by new ones. It is noticeable that in the Ptarmigan it is also the white feathering of the chin and of the breast and belly, as well as of the wings and tail, which is changed once only in the year, exactly as with the winter plumage of the Grouse. It suggests that these two plumages are analogous in each species. The plumage changes in the Ptarmigan are, strange to say, quite different to the chancres in the Grouse. The Ptarmigan has three distinct moults and plumages in the year. The Red Grouse has but two. In August, as has been said, the cock Red Grouse has begun to put on his winter plumage. The feathers of the breast and abdomen are full of sheaths and sheath-scurf, the growth of these feathers being very rapid and often scarcely noticeable. On the rump, back, and to a less extent on the shoulders, new rich red-brown feathers finely marked with black lines are showing here and there. Primaries, secondaries, tail feathers, and coverts are now replaced by new and blackish feathers with perfect and unbroken outlines. Even a few new rich copper-coloured feathers are appearing as isolated touches of bright colour amongst the faded broad - barred autumn feathers of the upper breast. The feet and legs are bare, save where new white feather tips are just appearing through the skin, and the claws of all the healthy birds are being shed (PI. xiii., Figs. 3, 4, 5, 6). In September the chin and throat of the cock Grouse are a mixture of many pale autumn feathers much worn and faded, and a few new g copper-red ones. Most of the frayed "autumn plumage" feathers t'^'^^®'"- are now falling out. The breast and abdomen, wings and tails, are clothed with altogether new feathers, while the head and neck, back, shoulders, rump, and coverts of the tail are in a transition state, the " autumn " feathers frayed and bleached at the tips, contrasting with the new rich chestnut and darker brownish winter feathers with their fine black transverse markings. 42 THE GROUSE IN HEALTH AND IN DISEASE The feathers of the legs and feet of healthy birds are rapidly growing to form thick, white stockings for the winter. Bare legs in September are a sign of belated moult or, in other words, a sign of sickness. In October, for the first time since the preceding winter, the red and black varieties of Red Grouse become once more conspicuously distinct. This result is due to the new growth of fully pigmented feathers, either October. j i. o red or black, upon the under surface of the body. The upper neck is rapidly becoming copper-red. The chin and throat still show a proportion of the faded buff "autumn" feathers among the red, the former looking spotty and pale. On the back the new chestnut and black feathers are rapidly replacing the faded autumn feathers. Some perfectly healthy cocks still look as if in " autumn plumage," while others, on the contrary, have nearly com- pleted their winter dress. The legs and feet are thickly covered with white feathers, and the nails are uniformly small, as the old claws have all been shed. Their growth, however, is extremely rapid. In November and December the cock Grouse drops most of the remaining "autumn plumage." By the end of the latter month his moult is com- Noveinber x a j and plete, but on the neck and back a greater or lesser number of these December. ... autumn feathers are retained till the following summer. The most striking characteristics of the winter plumage are the rich copper - coloured neck and throat, and, in the darker varieties which are common in the Scottish Highlands, the contrasting blackness of the upper breast and abdomen often broadly flecked with pure white tips. Amongst the cocks there are several well-defined and easily recognised varieties, which seem to have a certain regularity of distribution geographically. These will be considered below. It must not be forgotten that, owing to innumerable efibrts, which have been more or less successfully made from time to time, to transfer Red Grouse from one part of the country to another, the distinction of local variations has become a thing of the past, and is now impossible except upon a very limited scale. The attempt, however, can be made, and the number of specimens in the Committee's collection of Red Grouse skins makes it possible to arrive at some conclusions. PLUMAGE CHANGES OF THE HEN GROUSE 4-3 Part U. — Plumage Changes of the Hen Grouse. The two changes of plumage in the hen Grouse are completed, as has already been explained, in the one case by the end of April or the begin- ning of May, and in the other case by July and August. *= -^ . Seasonal The actual feather changes in both cock and hen are really very changes of plumage. comparable in character, notwithstanding the difference as to season ; and allowing for the difference of two months which makes the moult in the two sexes asynchronous, they may be described and explained in very much the same terms. Mr Ogilvie-Grant was the first to draw attention to the exceptional want of agreement in the seasons chosen by the two sexes of the Red Grouse for their moult, and as in the cock's plumage he makes use of the ,, . ,, . ,, - Explaua- terms "autumn and winter - summer or "winter plumages, tionof tGrms which have therefore been used here, so in speaking of the hen's plumages it will be well to adhere similarly to the expressions used by him, and to call them "summer" and " autumn - winter " or "autumn" plumages. Exception may be taken, and indeed has been taken, to these names, as being inappropriate and inexact, but they are sufficiently exact for all practical purposes, and so long as moults and plumage changes are not completed in a week, but are spread over a period of several months, so long will there be some inexactitude in the terminology of these moults and plumages if they are named according to the months or seasons. It is immaterial so long as the term is sufficiently defined, for it is obviously impossible to use a term so exact as to require no definition. The hen Grouse moults twice in the year, and wears her "summer plumage" as the breeding dress from April to July, and her "autumn" or " autumn to winter " plumage from August to March. These changes may be expressed in terms of comparison with the cock, as a case of plumage change in which the hen has two annual moults, exactly as has the cock, but both moults occur two months earlier in the hen than in the cock. The hen's "summer" or breeding plumage is a very beautiful dress, 44 THE GROUSE IN HEALTH AND IN DISEASE variable to a considerable extent it is true, but yet having a general uniformity which becomes the more obvious as a greater series of skins in any particular phase of plumage is examined. Opportunities for even seeing the hen Grouse, to say nothing of obtain- ing her skin, in the full breeding plumage are rare ; and thus it happens that, even in the large series of Grouse skins at South Kensington obtarninK° and at Cambridge, this jDhase is only poorly represented, of nesting The Committee has been to some extent more fortunate, and pumage. j^^^ obtained a great many skins of hens in the summer plumage (see p. 54 and Appendix D), so that points of resemblance can ])e noted at sight, and individual variations perforce take their proper places. It has been a marked feature in the whole collection of six hundred skins that as the series grew, and the general uniformity became more marked, the individual variations of which we were inclined to make much at first, became gradually relegated to their subordinate position. Uniformity, albeit with endless minor variations, is the rule in the Grouse as it is in every other creature that leads an unprotected existence under natural conditions. How long it will continue in the protected, often over-protected. Grouse remains to be seen. It is possible that such variation as already occurs is to some extent a modern development ; but on this point there is at present insufficient evidence to amount to certainty. Beginning once more with January, it may be said that in this month some hens, when examined on the under side, are hardly distinguishable by their plumage from some cocks (PI. viii.). On the dorsum it is difterent, and a healthy hen in January is unmistakable owing to the terminal spots of buft' which appear almost invariably, though occasionally in limited numbers, on the feathers of the back. In some healthy hens the chin is sometimes still pale buft" in colour, owing to the persistence of summer-plumage feathers of the preceding year. The throat and fore-neck, on the other hand, are copper-red, but rarely so uniformly red as in the cock (PI. XVI., Fig. 1). The copper - red feathers seem to begin on the fore-neck and proceed towards the chin, so that the chin often remains buff and black when the throat is already red. Except in very backward birds, which have been sick, the old and faded broad-barred feathers of the flanks are never found in January. The legs and feet are white and thickly feathered, and the claws are long and strong. PL VIII. (p.z.s. 1910. PI. z.v.v.vr.) £^i|s»!? Andre & Sleigh, Ltd. FEMALE GROUSE, BLACK TYPE, IN AUTUMN-PLUMAGE. .' ,!l^ PI. IX. (p.z.s. 1910. p/. /.v.v.vr//.) Andre & Sleigh. Ltd. FEMALE GROUSE, RED TYPE, CHANGING FROM WINTER- TO SUMMER-PLUMAGE. PL X. (p.zs. 1910. /■/, /.v.v.vr/.) *»*r:-'' ; 1^ Y V • -^--*-^ m Andre & Sleigh. I.tJ. FEMALE GROUSE IN FULL BREEDING-PLUMAGE. PLUMAGE CHANGES OF THE HEN GROUSE 45 In February the bird is still in the same plumage as in January. In a few forward birds the feathers of the summer dress are beginning to make their appearance on the back of the neck about the middle of the month. In March the change from autumn plumage to spring breeding plumage is, in healthy birds, now quite unmistakable, though many birds are very backward owing to disease. All doubt as to the sex of healthy birds, whether from above or below, is now removed. The broad- barred buff and black feathers of the flanks are now appearing, and are most conspicuous and characteristic, while the whole of the lower breast and abdomen covered by the red-brown or red-black finely barred feather of September growth are still in excellent condition and remain unchanged (PL IX.). The feathers of the chin, throat, neck, and upper breast are now mixed with broad-barred black and yellow feathers in forward birds ; while in backward birds the throat and fore-neck may still be clad in copper-red feathers. The legs and feet are already looking worn and less well feathered, but the claws are long. In April and in May, for the simple reason that many hen Grouse died of "Grouse Disease" in these months during the six years of the Inquiry, the proportion of skins of l^ackward hens is large. The birds thus Aimiand picked up dead carry one immediately back again to winter, for -"^^^y- although they ought by this time to be putting the finishing touches to their spring plumage, they are, in fact, but just succeeding in the belated effort to put on the autumn dress. They are thus a clear six months late, and afibrd the most misleading seasonal characters imaginable. Their legs and feet, instead of being worn and almost moulted clean, are at last, after a winter spent with almost naked legs, well-clothed with thick white feathers. The appearance of the legs therefore in the hens, as in the cocks, is totally misleading to the keeper or to the sportsman who considers bare unfeathered legs to be a sign of " Grouse Disease." This holds good for autumn only, and in spring precisely the opposite is the case, for in April, May, and June none but healthy birds have naked legs and feet. The general character of advanced and healthy birds towards the end of April and in May is that of a complete spring plumage. The whole of the upper parts are broadly barred with buff and black, and marked with con- spicuous terminal whitish buff spots or bars (PI. x.). The under parts, again, are 46 THE GROUSE IN HEALTH AND IN DISEASE broadly barred with buff and black, from the chin to the throat and neck, over the breast and down the flanks, while the central lower breast and abdomen are still in the autumn plumage of the previous September (PI. XI. and XII.). White terminal spots may, of course, be present on the breast and abdomen. These are a local or an individual character which will be mentioned later in dealing with varieties of feather pattern and coloration. The flank feathers of the hen in the full spring plumage show much diversity of pattern. This diversity even in the same individual bird Change of ^^^ ^^^ ^^ ^^'^ belief that the pattern may be changed in an unmoulted tion'im-*^ feather from the autumn plumage arrangement of red -brown and probable, j-eddish - black finely barred with lines of black to a much bolder barring of bufl' and black. It has been surmised, from the examination of sinorle feathers, that the change commences in the centre of the feather on either side of the shaft, and gradually produces another pattern of a totally different colour. But can this be possible in a feather which has long been fully grown, and which has presumably been long cut off from any blood or lymph supply, and which is as dead as if it had been shed? (PI. xii.). It is almost certain that re-arrangement of the pigment or of the pattern in this way is out of the question, and the reasons for this view have already been di.scussed.' The legs and feet of the hen Grouse in April and in May are very poorl}' feathered, and the claws are very long (PL xiii., Figs. 3, 5). In June the legs and feet are almost bare, and the claws begin to drop off (PI. XIII., Figs. 3, 4, 5). The precise date of this shedding of the claws is again really a part of the moult, and is, in consequence, equally dependent upon the health of the bird. Sick birds which have sur- vived the spring mortality are always late in the shedding of their claws, and Shedding equally late in the changing of their feathers. The claws are shed, of claws. Ijoth in health and in disease, but once a year, and the castiner is synchronous as a rule with the disappearance of the autumn dress. The figures (PI. XIII.) by which this process is illustrated require but little explanation. The whole of the year's growth of horny black nail becomes loose on the soft and growing vascular matrix, and when quite ready to be cast can be easily jjulled off like a little cap. The young nail beneath is at first soft, pink and vascular and very short, but soon hardens and deepens in colour, and in a month or two has grown to be a useful nail of horn. The transverse or circular groove which is ' Vide pp. 37-40. PI. XI. (P.Z.S. 1910. /7. Z.V.V.VI7//.) Andre & Sleigh. Ltd. FEMALE GROUSE IN FULL SUMMER-PLUMAGE. PL XII. (P.Z.S. 1910. PL -vr.) Andre Si Sleigh. Ltd FEMALE GROUSE, RED TYPE ; FEATHERS FROM FLANKS. Female sniuse, led type, feathers from Ranks. Natural size. Fig. a and t (from No. 1864*. fi and h (from No. 226). and k (from No. 632). are varieties of the spring Hank-feathers. Fig. b (from No. 575) is a Hank-feather from a very black hen. Fig. d from No. 1864) is an example of what is termed fine-barred, dark-red winter-plumage, with narrow black bars or lines on rather dark rufous chestnut, the latter being slightly bleached towards the tip. Figs, <■ and/ (from No. 1864 > and / and m (from No. 664 > illustrate interme- diate stages of colouration, the feathers probably having broken through the skin w-hen winter-conditions prevailed, and having completed .their growth under summer-conditions. Figs, i and n (from No. 664) illustrate the reasoning upon which is based the view just mentioned : of these two feathers there is no doubt that n was being grown much later than (. and therefore more in summer-condi- tions, producing summer breeding-plumage. PL XIII. (P.Z.S. 1910. PL XCIII^ C / ^ / 5a 5b 6c 5b 5c Andre & sleigh. Ltd. FEET OF RED GROUSE: (1) NEW WINTER-FEATHERS AND NAILS; (2) FULL WINTER-PLUMAGE (3) (4) (5) and (6) SHOWING STAGES IN MOULTING OF NAILS. XIII. Grouse, red type, feet showing winter-plumage. Fig. 1, Right foot showing new winter-feathers and new nails ( Xo. 1177). ., 2. Left ft>ot showing full-feathered winter-plumage. Feet of grouse, showing replacement of nails. Fig. 3. Right foot (No. 1148) with old nails ready to be shed. .. 4 in median vertical section. .. 5, Left .. (Xo. 1167). 5rt. old nails : 56. new nails : 5c. shed nails. .. 0. Right .. (\o. 1185) with new feathers and new nails. PL XIV. (P.Z.S. 1910. PL ZA'.V.V/.V.) Andre & Sleigh. Ltd. FEMALE GROUSE SHOWING BARE PATCH OF SKIN AND DOUBLE LINE OF BARRED FEATHERS ON ABDOMEN. PI. XV. (P.Z.S. 1910. PI. .VC/.) Anilie S SleiKh. LtJ. FEMALE GKOUSE, RED TYPE ; WORN UPPER TAIL-COVERTS. PLUMAGE CHANGES OF THE HEN GROUSE 47 left at the point of detachment of the old nail is quite a useful indication of age in cases where there is a doubt as to a bird being over twelve months old or of the year. The presence of the groove showing that the claws have once at least been shed is conclusive proof that the bird is more than twelve months old. In Ju7ie there is another characteristic appearance in the hens, namely the bare patch of abdominal skin which results from the shedding of the abdominal feathers, grown in the previous September. The loss of these feathers leaves a naked patch of skin on the abdomen of a hen that has been on abdo- men. sitting, and this patch remains naked for the next few months (PL XIV.). The general character of a June hen in health is that of the completed summer-nesting plumage, broad-barred buff and black over all the upper and under parts, excepting the abdominal area, the lower breast, wings, and tail. But it looks already somewhat faded and worn ; and it is quite probable that in acquiring so perfect a plumage for sitting unnoticed on a nest built amongst the heather, the economic absence of the redder pigment in the feathers is in part a result of the acknowledged fact that for longer and more trying use, and for wear and tear in feathers, darker pigments are required, whereas for the short- lived and less exacting requirements of the summer plumage in the hen Grouse from April to June the buff and black feathers, with very much poorer wearing qualities, are found to be sufficient. The accompanying figures of a few worn- out and moulting feathers taken from a hen in summer plumage, show how distinctly better the black pigmented parts of the feather stand wear and tear than the yellow parts (PI. xv.). Certain pigments have a value, therefore, of a very practical nature apart altogether from the sesthetic point of view of attractiveness, or the rather hypothetical view of assimilation to surround- ings for purposes of safety or to assist in obtaining food. He would be unwise, however, who denied that all three factors play a part in the very beautiful nesting plumage of the hen Grouse. It very occasionally happens that the hen Grouse, instead of retaining the redder plumage of the previous autumn's growth on the abdomen until it drops off during incubation, grows an almost universal spring plumage of buff and black broad-barred feathers covering the lower breast sometimes absent. and abdomen as well as the remainder of the body from head to tail. A skin showing this condition is preserved in the National Collection, and there is an almost equally perfect specimen in the Committee's Collection, No. 919. 18 THE GROUSE IN HEALTH AND IN DISEASE The more usual procedure is that the abdominal patch of autumnal plumage is lost during incubation, and is then quickly replaced by a renewal of the autumnal feathers when the spring plumage is also beino- shed. Peculiar . .... . growth on There remains, however, in the majority of birds, a very quaint abdomen. growth of belated spring plumage, consisting of buff and black- barred feathers in two lines down each side of the centre of the naked patch, as though, for some occult reason, the intention to grow "spring- plumage" feathers upon this area had never been altogether lost. This peculiar persistence of belated intention shows itself as a patch of yellow feathers made up of the two lines of feather growth in the midst of a much broader area of the autumn red pigmented feather which one would expect to find all over the abdomen (PL xiv,). It is conceivable that a small persistent remnant such as this, having no obvious connection with the surrounding plumage at the time, or with the habits of the bird, or with the seasons, may yet have something to do with the third or lost " eclipse " plumage which is still to be found in the grey plumage of the Ptarmigan, but is almost completely lost in the case of the Red Grouse. In July the summer plumage of healthy hens is much worn out, frayed at the edges, and very definitely faded, and the feathers are already dropping out. On the chin, throat, and fore-neck, new red feathers of the autumn plumage, looking rich and dark, are already making their appearance. The back is as it was, but faded, and the flanks are still con- spicuously broad-barred with buft' and black ; but the abdominal l)are patch is now growing new autumn plumage feathers with great rapidity from the centre outwards. The primaries and secondaries have now commenced to moult. There may be in July, in the hen, as many as six or eight old primaries in each wing with frayed tips, still to be renewed. Precocious young birds of the year can still at once be distinguished from hens in moult, because in the former the dark red-brown black-lined autumn Distinction plumagc is ou the flanks, while the broad-barred bufi" and black, and between rather worn-out chicken feathers are in the centre of the abdomen. In young and old birds, ^^j^g adult the distribution is reversed. The broad-barred buff and black feathers of the spring plumage are on the flanks, and the redder fine-barred autumn plumage is appearing in the centre (compare PI. xii.. Figs, a, c, g, h, k, and n, with Fig. d.). In skin No. 284 there seems to be an unusual compromise in a very backward hen, owing to disease. The compromise is between the i: 2 N PQ S o o >-) o p :-?±i-.;>'*;-.i ; Jl^'v -.( PI. XVII. (P.Z.S. 1910. >"/. .Vtl/.) AiiJi-c .3; ^l(;i^lh, Ltd. HEAD OF BLACKCOCK. SHOWING SUPRA-ORBITAL COMB. PLUMAGE CHANGES OF THE HEN GROUSE A9 broad - barred and the winter plumage with its very fine black cross - lines (PI. XII., Figs, e, f, I, and ni). The legs and feet in July are naked, and the claws are very small ; but the feathers are already showing through as small white points, not to be confused with broken shafts, which occasionally result from wear and tear in woody heather. The plumage of the hen Grouse in August is well known. It has already been pointed out how, owing to the sudden increase of observation, and owing to the sudden arrival of opportunities for examining an enormous number of birds over the whole country during this month, there has sprung up an idea that disease amongst Grouse has a recrudescence in the autumn. But this is not the case. There are probably fewer diseased -^^ birds on the moor in August than there are in July. In July, o"tb™°]j however, they are never shot, and therefore not investigated, but in of disease. August they are carefully picked out of every bag, and, owing to the general interest in the question of disease, are almost always noticed, and in a large proportion of cases publicly notified. Hence the idea that disease makes a new start in August and September. As a matter of fact, however, these wasted birds are almost certainly convalescent. They have been diseased, and they are still suffering from disease, but thanks, in the majority of cases to their sex (for the bulk of the sickly autumn birds are hens), they have avoided actual death in the two highest mortality months, April and May. Once tided over these fatal months, the food and general conditions of life improve, the weight of the cock goes up, and the balance is again in favour of recovery for him ; and although with the hen the exigencies of incubation and the cares of the family continue to handicap her until June and even July, she then rapidly begins to put on weight, and in August and September is once more on the way towards complete recovery. Many sick-looking "jjiners" are shot upon the moors in August, but it should be remembered that in that month they are recovering from disease, and not growing worse ; while in September many that were not up to the average weight the month before will be practically normal and probably indistinguishable from healthy birds, were it not that their serious indisposition of the preceding months has put them behind their fellows in the matter of feather change. In August, therefore, the Committee's collection of skins contains a large number of examples of hen birds showing deferred moult and belated growth VOL. I. D 50 THE GROUSE IN HEALTH AND IN DISEASE of feather. The normal healthy hen Grouse in August has already put off most of the broad-barred spring plumage feathers of her nesting dress, and is very much like the cock bird in appearance, with the same dark, red- brown vermiculate or fine - barred plumage underneath, white - flecked or not as the case may be, and with a mixture of old and new feathers above. The legs and feet of a forward hen are already showing quite a fair growth of white feathers, and the nails have all been shed. The claws are therefore short and rather soft, and the transverse sulcus or groove at the point of detachment is clearly marked. In the wings there may still be a number of primaries to be changed. In the convalescent " piner," on the other hand, the case is often very •different. She has still a most deplorably bleached and weathered breeding plumage on her, with worn-out feathers, frayed or ragged, often with saw- toothed edges, showing the unequal effect of wear and tear on the pale bufi" pigmented and black pigmented parts. The bird in this belated plumage has quite naked legs and feet and long unshed nails, or may at the most be just showing the points of a new growth of feathers through the skin ; and in this state she is conspicuously shabby and ill to look upon in comparison with the splendid plumage recently acquired b)^ her healthy sisters, and by the now almost universally healthy cocks. But the point above all others to be remembered in this connection is that this hen is convalescent, and still has a couple of months of good food and good weather, as a rule, in which to complete her convalescence before the winter comes. If the spring outbreak of disease has been severe — that is, if the general ■conditions of the preceding winter and early spring months have been such ^.„ as to conduce to a heavy and widespread infection of the Grouse Different -' "^ effect of with the larval Trichostronqylus — then both cocks and hens will disease . in cocks be equally infested. But the breeding season and the concomitant and hens. s. j o needs of the two sexes are, from April onwards, quite distinct from ■one another. The result of this is that there is often a large mortality of cocks in April and in May, and a much less marked mortality of hens, probably in the proportion of seven or eight cocks to one hen, but definitely occurring in the same two months. There is no great mortality from Strongylosis in any other months of the year and after May, the cocks are suddenly relieved and rapidly recover, PLUMAGE CHANGES OF THE HEN GROUSE 51 so that by August there are almost no sick cocks ; the hens, on the other hand, have still two very trying months to face, and although, thanks to the abundance of food, probably most of them succeed in struggling through, yet by August they have only just been freed of their more pressing cares and disabilities, and so a very great number are still found to be in very poor condition. The moment the disabilities are removed, however, they begin to recover, and it is this point which has so constantly been overlooked. Sick birds in August are convalescent, and however many there may be, it is not a sign of a new outbreak of disease, but a sign that the past spring infection was a heavy one, though less fatal than it might have been. At the end of their own specially critical periods, the cocks have at any rate June, July, August, and September in which to pull themselves together by means of good food assisted by good weather ; whereas the hens, at the end of their own specially critical period, have August and September. Hence the preponderance of sick-looking hens when the shooting begins, and the widespread, but erroneous, belief in a recrudescence of disease in autumn. To return to the further consideration of the hen's change of plumage in September, her finest feature is now undoubtedly the clean new growth of bright red, or dark red or even black and white-flecked feathers of the breast and abdomen, with their narrow but even blacker markings. The whole of the feathers of this tract have now been shed, but they grow again so quickly that no bare skin is visible save in the middle area of the abdomen quite low down, where, as has been already pointed out, the new growth is of belated feathers coloured as in the spring plumage, and therefore quite difi"erent from those around them. There is still, as a rule, no accession of new red feathers on the chin or throat of the healthy September hen, or at the most but a feather or two. But in the sick hen there is still often a sprinkling of the old red feathers of the preceding autumn plumage, very faded, amongst the faded buff and black feathers of the belated spring plumage. On the back of even forward hens there is still a mixture of old and new plumage, and the scapulars are often faded to something like black and white, and are badly frayed at the ends. The wings have now almost completed their moult, but there may still be a primary or two to change, even in very forward birds. The legs and feet are rapidly becoming feathered for the winter, though in backward birds which have been sick they are 52 THE GROUSE IN HEALTH AND IN DISEASE still quite bare, and now, of course, this feature may truly be taken to be a sign of sickness and disease, though in a convalescing bird. In October one may find a very backward bird with as many as three worn-out primaries in either wing to change ; but, as a rule, the wing is perfect, the primaries and secondaries and their coverts all completely new, and in the tail the rectrices are full grown. The legs and feet are now also fully feathered, though the thickness of the growth increases as the winter cold comes on. On the back the bird now looks fresh and richly coloured, from head to tail, but a close search will always disclose a number of spring-plumage feathers which have still to be thrown oti'. Underneath, the rich red-copper colour is gradually replacing all the previous buif on the chin and throat. The change "hangs fire" a little on the neck and upper breast, but it is still progressing, whereas on the lower breast and belly the rich red or darker winter plumage with its beautiful fine black cross- lines and pure white flecks is a very striking feature. There are, in the Committee's collection of skins, a number of examples showing the result of disease in deferring the moult ; many of these birds, even in October and November, have made no efiort to get rid of the old, faded and completely worn-out spring plumage. The majority of these birds have been so diseased m spring that they have not bred at all. The ovaries have throughout the season shown no development, and there are no signs, even in the earlier months, of the shedding or development of ova or of any increase in size of the oviduct. They have been true barren hens. In some cases {e.g., in No. 1247) there appear, in November, feathers of three separate plumages. There are the faded spring-plumage feathers of the current year, but mixed up with them here and there are new feathers of the autumn plumage coming, and here and there exceedingly old worn feathers of the autumn plumage of the year before. No. 1225, an October hen, shows exceedingly well how the bare, broody patch of the abdomen grows delayed broad - barred bufl:' and black feathers instead of the fine- barred darker autumn - plumage feathers which surround the patch. These broad-barred feathers appear in two parallel rows, breaking through the skin of the broody patch on either side of the medial line ; this growth is also well shown in a specimen at the British Museum of Natural History (PI. XIV.). In November the chief alteration is the completion of the autumn moult LOCAL VAEIATION IN PLUMAGE OF GROUSE 53. and the assumption of the autumn plumage. The feathers of the upper parts have black middles, and are barred with rufous - chestnut and ^^ Is oveiu ber. ornamented with the characteristic white or butf-coloured terminal spots. In December the hen is in full autumn- winter plumage. On the legs and feet she is well and thickly feathered ; and on the under side the chin and throat are dark red, as well as the fore - neck, marked with December. broader black bars than upon the lower breast and abdomen, where the marking is "of the finer type, and the colour distinctly of the redder and darker autumn plumage. Part III.-^Local Variation in the Plumage of the Grouse. The following notes are the outcome of an attempt to find some broad differences between Grouse from the Highlands, the Lowlands, the east coast and the west coast of Scotland, and from English, Welsh, and Irish moors. It seemed possible that, with a large series of skins of a species peculiar to the British Isles and at the same time so variable, one might discover points in the coloration of the plumage or in the size of the birds which could be attributed to the varying physical conditions under which they live. The artificial transportation of Grouse from one county to another, generally from the southern moors to the northern, often far removed from one another, with different food and climate, has no doubt to some extent Effect of confused the issue. But this is a difficulty which will increase ing fresh rather than decrease, and it is possible that the purity of the British breed (at present the only species of bird peculiar to our islands), may before long be entirely lost by the introduction of a foreign species, the Willow Grouse, on the mistaken supposition that the latter is freer from the parasite of " Grouse Disease." The foreign species has already been introduced here and there, and there has been some interbreeding with our own Red Grouse. Hence there was some reason for thinking that, unless the opportunity for collecting a series of pure bred British Red Grouse skins had been taken by the Committee, the same wide opportunity might not have occurred again before the introduction of foreign species had become popular. The Committee's collection contains five hundred and eighty skins of the Red 54 THE flPvOUSE IN HEALTH AND IN DISEASE Grouse, including five hundred and forty adult birds of both sexes and forty chicks and pullets. These, however, cannot l)e taken all together in one series. It is essential, for purposes of comparison, that the male Method of . . i i • studying birds in their two plumages should be taken separately m two lots, and the females in a similar manner. Therefore the skins have to be divided as follows : — Male birds in winter plumage Male birds in autumn plumage . Female birds in autumn plumage Female birds in summer plumage Immature birds of the first six months No. of skins. 241 120 108 71 40 oom- parison The largest series of skins is therefore that of the male birds in winter plumage, and it so happens that this set, both as regards sex and plumage, is best adapted by its general uniformity to give some result when arranged map-wise over a large outline of Scotland and England. An analysis of the greater part of the collection of skins is given in the Table on p. 55. Having thus arranged the skins into lots which are sufficiently uniform R suits of ^^ allow of comparison, and having arranged one of these lots, the cocks in their winter plumage, for instance, according to the localities from which they were obtained, it becomes possible to make the following deductions : — (1.) That the general uniformity is very much more marked than might have been expected considering the character for variability which has always been attributed to the bird ; the variability is lost in the mass, though it is visible in individuals. (2.) That, allowing for a good many exceptions, there is certainly a greater tendency to blackness in the birds of the northern Highlands than in those of the south. Or, one may say that in passing from the north of Scotland southward and westward, there is an increasing tendency to the bright red and dark red types of Grouse, which culminate in the very characteristically bright red bird of Wales and of the Midlands of England, in which the predominating colour of the feathers of the breast and under parts generally is red with LOCAL VARIATION IN PLUMAGE OF GROUSE 55 fine broken black cross-lines, while these cross-lines are sometimes almost absent. (3.) This gradual change from north to south of black, or red and black tO' dark red cocks, and farther south to bright red cocks is accom- panied (speaking very broadly, for there are many exceptions) by a loss of the white terminal borders which characterise the feathers of the abdomen. ■ r ^ r ci- ■ -i ^ /• summer. irom a comparison oi the aiternoon crops oi the winter with those of the summer, this appears to be the case. Thus the average weight of food found in a Grouse crop from December to March, between 3 p.m. and 6 p.m., is 250 grains, whereas the average weight of food found in a Grouse crop from April to November, between 3 p.m. and 6 p.m., is only 50 grains. The fact that more food is required in winter to maintain the body temperature would, of course, partly account for this increase, even Reasons if the heather had the same food - value. But as heather certainly ^°'' *^'^' has an inferior food - value in winter, the amount taken must be increased ' Vide p. 80. 80 THE GROUSE IN HEALTH AND IN DISEASE CHART SHEWING PERCENTAGE CONSUMPTION OF VARIOUS FOODS EATEN EACH MONTH BY THE RED GROUSE /oo 95 SO 86 80 75 70 65 60 55 50 f5 35 JO 25 20 15 10 5 0 >- < < —> >- «*: cc CO UJ X < a. < UJ Z ID -3 o < CD i: LU »— Q. U-l DC UJ OQ o o CO UJ > o ex. u_) CO U_l a HEflrHER TOPS. fCa//c//>a yu/garisj HEATHER FLOW£/f AND SEEDHEflOS (Calluna vu/gans) BLflEBERRYSTEM AND BUD (ITaccinium myrlillus) VARIOUS. 90^. -il/ 89 A / \ > r \/ \ V 7$!^ / 7d'/e \ r 73% TV? \ 1 \ \ I /\ / \, A / v 1 V ^ SfJ'o- ^^^* ,T,f 26" .^, Vr^f < « • • • ^222 \ \ 17 • '■I8?a • t ^//^ \ \ ^ •'10 / ^hh > \ \ > 6^8 \ W ../ / 5^4 7^, / / * • '"!•/,••' .•3yz.. ^ / '" -^ '^2^4' ,^-' * J... ••2^J. OBSERVATIONS ON THE FOOD OF GROUSE 81 in a far greater proportion. No doubt the necessity for provision during the longer hours of night-time has some efi'ect in the overfilling of the crop in winter, but this would not account for crops being heavier in March, when the days are comparatively long, than in November when they are short. The interesting fact remains, and is amply proved by the figures, that more food is required by the Grouse in winter than in other seasons of the year ; and as in winter the proportion of Calhina to all other foods is as seven to one, it is obvious that a very great advantage accrues to a Grouse on a moor in which young and comparatively nourishing heather is abundant during the winter months, i.e., on a well-burned moor, well covered with young heather of a varying number of seasons' growth. To put this conclusion in other words ; whereas in summer a certain area of heather will support a bird comfortably, many times this area will be required for the same bird in the winter, so that the capacity of a moor, as regards the question of stock, must Ije gauged mainly by its Grouse-feeding value during the winter months. If we consider this generalisation with reference to moor management we shall see that a moor carrying its full tale of birds in the summer becomes automatically and unavoidably overstocked in the winter unless the stock is heavily reduced by shooting, for not only is there less food available, but the birds require a much larger quantity of food to keep them in health. Migration of birds in winter obviously complicates the question. In the case of a moor on high ground, which often loses all its birds in winter, probably natural conditions regulate the stock of birds automatically Effect of during spring and summer. But on the adjacent low-lying moors '"'g^'^tioii. the case is more serious ; for the ground has to supply not only more food than is needed for its own stock in summer, but in addition an increased seasonal demand made upon it during the winter months by hundreds of undesirable immigrants from the higher ground. Such low-lying moors must always run the risk of being dangerously overstocked in the winter. In certain parts of the country oats form a regular seasonal change in the dietary of Grouse, and this form of food must now be considered.^ Very few birds with corn in any part of the alimentary canal were submitted for examination ; but so far as these specimens show, oats are an unsuitable form of food for Grouse. As is well known. Grouse often visit the ' Vide also chap i. p. 25, and chap. viii. pp. 178-180. VOL. I. . - P 82 THE GEOUSE IN HEALTH AND IN DISEASE stubbles and corn-stooks in very large packs in the autumn — in September, October, or November, according to the season and locality. They seem to know that they are out of place, and finding themselves with a wealth of food all round, away from their normal surroundings, are eager to fill themselves as full as possible in a very short space of time, aware, by instinct or experience, that they may be disturbed at any moment. One consequence is, as the examination of birds has shown, that they eat as much husk as grain, instead of picking and choosing as Partridges do, in a quiet and leisurely manner. This difference in the crops of Grouse and Partridges that have been feeding on the same ground is very noticeable. The one is filled to repletion with indigestible and exceedingly irritating husks and a compara- tively small amount of grain, while the other (the Partridge's crop) contains grain only. The result in the Grouse is that the whole alimentary canal, from one end to the other, is soon in an irritable and inflamed condition. The gizzard does what it can to work up the husks and grain into a milky paste, but the microscope shows that this paste is to a large extent composed of siliceous spicules and small spines of an almost glassy hardness. This damages the delicate mucous lining of the intestine. The result of the passage of this irritating food is, first, an extra flow of digestive juices, secondly, an increased activity on the part of the walls of the intestine, both as to movement (peristalsis) and secretion from the stimulation produced by this form of food. Thirdly, comes a point at which mucus is thrown out in large quantities to protect the gut, and this continues and increases until the actual cells them- selves are shed, and the protection breaks down. Finally, the intestine becomes inflamed to the extent of ulceration, and this state will continue and increase so long as the cause continues to act. Such irritation to the intestine of even a healthy Grouse, which already has to deal with worms of at least two kinds, is bound to have an evil effect if continued for any length of time ; moreover, in places where the corn is left out owing to bad weather, or for other reasons, there is the additional aggravation that the birds may be filling themselves with wet and sour grain, not one whit the less irritating as regards the husk, which cannot be softened by wet ; and no doubt the consequence of this is in some seasons noticeably bad. Corn in moderation is probably not unwholesome as a food, and were it OBSERVATIONS ON THE FOOD OF GROUSE 83 possible to feed one set of Grouse with clean grain, and another with such stuff as the birds pick up for themselves on the stubbles, there is no doubt that the former would rapidly improve in condition, and the latter go steadily downhill. Such an experiment is not practicable. To recapitulate, the following may be given as a fairly accurate account of the monthly dietary of the Red Grouse for the year : — January, Calluna shoots (64 per cent.) and Calluna seed - heads (27 i^er cent.). February, Calluna shoots (75 per cent.) and the stalks and buds of blaeberry and leaves of cowberry. March, Calluna shoots (97 per cent.) and blaeberry stalks and buds. April, Calluna shoots (93 per cent.) and very little besides. May, Calluna shoots (82 per cent.) and rather more "various." June, Calluna shoots (82 per cent.) and "various." July, Calluna shoots (53 per cent.) and an increasing amount of " various." August, Calluna shoots (60 per cent.) and some Calluna flowers and "various." September, Calluna shoots (63 per cent.) and 16 per cent, of Calluna flowers and " various." October, much less (42 per cent.) of Calluna shoots, and nearly 30 per cent, of Calluna flowers, and some " various." November, still less (39 per cent.) of Calluna shoots, and 33 per cent, of Calluna flowers and seed-heads, and the rest " various." December, a rise in Calluna shoots to 60 per cent., but still 27 per cent, of Calluna seed-heads. List of Vegetable Food eaten from Time to Time by the Red Grouse Calluna vulgaris, the staple food of Grouse, is known generally as Heather. Grouse eat the shoots, flowers, and seed - heads. See PI. xxiii., p. 71. Vaccinium myrtillus, Blaeberry, Blueberry, or Blue Whortleberry. Grouse eat the stem, buds, flowers, and berries. See PI. xxiv., p. 86, Fig. 1. 84 THE GROUSE IN HEALTH AND IN DISEASE Vaccinium oxi/coccus, Bog Crauberry. The leaf and the berry are sometimes eaten. See PL xxiv., p. 86, Fig. 2. Vaccinium vitis-idmi, Red Whortleberry, Clusterberry, and (in Scotland) Cranberry. Leaf and berry are eaten. See PI. xxiv., p. 86, Fig. 3. ArctostaphyJos uva-ursi, Red Bear Berry. See PL xxiv., p. 86, Fig. 4. Ruhus chamcemorus, Cloudberry, or (in Cumberland) Noops. The leaf is eaten, and so are the berries. See PL xxv., p. 87, Fig. 1. Empetrum nigrum, Crowberry, Crakeberry or Lingberry. The top shoots, tight leaf buds, and berries are eaten. See PL xxv., p. 87, Fig. 2. Erica cinerea, Purple Bell Heather. The flower alone is eaten, but while it is out it is eaten in fair quantities. See PL xxv., p. 87, Fig. 3. Erica tetralix, Cross-leaved Heath. Flower-heads are eaten in quantities, but leaf-.shoots are avoided. See PL xxv., p. 87, Fig. 4. Salix repeiis, Dwarf or Creeping Willow, a low, straggling shrub from 2 inches to 1 foot in height. Foliage and young shoots more or less silky white. The plant has small oblong leaves, and bears small catkins in spring, followed by silky seed vessels. Found on sandy ground. Where it occurs the leaves and young shoots are grecdilv eaten. Myrica gale, Bog Myrtle, or Sweet Gale, an erect shrub, 2 or 3 feet high, fragrant when rubbed. It has long, narrowish pointed leaves, slightly toothed near the tip, and often downy beneath. It bears small catkins before the leaves are out. Always found in boggy places. The buds are eaten in winter and early spring, but sparely. Eriophorum, Cottonsedge or " Cotton Grass," two or three species of similar habit. A rush-like plant, bearing in summer, after the flowering period, conspicuous, white, cottony tufts, either solitary or in clusters of two or three or more. Grouse are very greedy for the flower of this plant in spring, and the tender shoots are also said to be useful when they first appear. The plant is then known by gamekeepers as "Blackhead" or "Mosscrop." It is found in marshy ground. Rumex acetosella, Common Red or "Sheep" Sorrel. A slender plant, from 3 or 4 inches to 1 foot high, often turning red. It has long, more or less arrow-shaped leaves, very acid to the taste. The OBSERVATIONS ON THE FOOD OF GROUSE 85 red-tinged green flowers are in terminal clusters on an erect stem, and are seen from spring to autumn. The plant grows in dry- pastures, and on open heaths. The seeds are greedily eaten. Juncus squarrosus, Heath Rush, a small rush about a foot high, growing in drier situations than most rushes. The flower- and seed-heads are very freely eaten. Luzula cahipestris, Field Wood Rush, a small rush with soft, flat, grass-like leaves, fringed with silky hairs. It grows in dry places. The flower- and seed-heads are eaten. The following additional list of plants, upon which Grouse are said to feed, is given in a pamphlet on " The Improvement of Grouse Moors," by the Rev. E. A. Woodruffe Peacock, who has examined the contents of many crops and gizzards of the Grouse. PotentiUa tormentilla, Tormentil. Trifolium minus, Suckling Clover. Galium saxatile, Heath Bed -straw. Pedicularis palustris. Marsh Lousewort. Pedicularis sylvatica, Heath Lousewort. The seeds of the following plants are greedily eaten, and are most useful as late autumn and winter food : — Alojiecurus myosuriodes. Mouse-tail Grass. Molinea coerxdea, Purple Melio Grass. Atriplex 2^c(,tula, Common Orache. Cerastium triviale, Chickweeds and other moor cerastia. Polygonum avicidare, and P. persicaria, Persicaria, and Knot Grasses of all species. The flower-heads are also eaten. Viola lutea, Yellow Violet. Pteris aquilina, Bracken Fern. In their season, too. Grouse are very fond of capsules of the moor mosses, such as the Great Golden Maidenhair Moss {Polytrichum commune), and the smaller fungi. For the purpose of reference the following plates and detailed descriptions are given of some of the moor plants most commonly confused on account of the variety of names by which they are known. 86 THE GROUSE IN HEALTH AND IN DISEASE PLATE XXIV Fig. 1 Fig. 2 The Blaeberry {Vatcinium myrtillus), known also as the Whortleberry, Bilberry, Whinberry, Blueberry, or "Whorts" in various districts, a low branched shrub 6 to 18 in. high, growing often in large green patches. The flowers, which appear in April, May, or June, are flesh - coloured, and the berries, which are black with a purple bloom, ripen in July and August ; they are agreeable to the taste. The Cranberry (Vaccinium oxycoccos), known also as the Bog Cranberry, Mossberry, Moorberry, or Fenberry, a very low plant with a prostrate, straggling, slender stem and small leaves. It is found creeping on the surface of the moss in boggy places. The flowers, which appear in June, July, or August, are solitary and bright red, and the dark red fruit is pleasant to the taste. This berry is common in many parts of England, but is little known in Scotland though the plant without the berry is sometimes seen. Tlie berry ripens in August. Fig. 3 Fig. 4 The Red Whortleberry or Cranberry (Scotland) {Vaccinium vitis - idcea), also called Clusterberry, Cowberry, Nutberry or Nubberry, Craneberry and Crawberry, a low straggling shrub with leaves resembling those of the box. The pink flowers are in terminal drooping clusters, and the berries are red. It flowers between June and August, and the berries ripen in September. Its leaves are to be distinguished from those of A rctostaphylos uva-ursi by the dots on the under surface and the rolled-back margins. The Red Bear Berry (Arctostaphyhs uva-ursi), also called Grassack or Graashacks, a small trailing evergreen shrub which grows in dry heathy and rocky places. The leaves are finely reticulated, and the berries are red and mealy, with hard angular seeds. The rose-coloured flowers appear from June to August in terminal clusters PLATE XXIV. r. G. M. Fig. 1. Fnxiiiiani iii>jrLdliM-i (BUeborry — Whortleberry — Bilbcrry- Wliorts — Whinberry). C. G. M. Fig. 2. VwxiiiiiiM oxycoccos (Cranberry — Mossberry). C. G. M. c. G. ill. Fig. 3. Fcuxinium vitis — Idosa (Red Whortleberry — Clusterberry). Cranberry {Scot.) Fig. I. ArctosUiphylos uva-iirsi (Red Bear Beiry- Gruashacks), Opposite ji. 86.] PLATE XXV. r. G. .1/. Fig. 5. Jlabus chaiiuemonis (Cloudberry — Averine). r. a. M. Fig. 6. Einpctrum nvjrum (Crowberry — Crakeberry). Fig, 7. Z^cica cjuccot (Bell Heather— Finc-leavcd Heath). Fn:. 8. AViVfj/rfraitj; (Cross-leaved Heath}. Opposite p. 87. ] OBSERVATIONS ON THE FOOD OF C4R0USE 87 PLATE XXV Fig. 1 Fig. 2 The Cloudberry or Averine (Rubus chamm- morns), a small herbaceous plant belonging to the Raspberry family with large green leaves growing among the heather on the mountain tops. It has large white or rose-coloured flowers, which appear in June and July, and the bramble-like fruit is orange yellow. The Crowberry (iiJii/jefrinn nigrum), Crakeberry, Lingberry or Blackberried Heath, a small prostrate plant with the habits of a heath. The purplish flowers, which appear in May and June, are very small, and are placed in the axils of the upper leaves. The ripened berries are black. Fig. .3 Fig. 4 Bell Heather or Fine-leaved Heath {Erica dnerea) has leaves three in a whorl. It grows on dry places and similar situations to common heather. The flower-bells are purple. The taste of the leaves is more bitter than that of common heather. It flowers in July and August, appearing before the common heather. Cross-leaved Heath {Erica tetralij:) has leaves four in a whorl and placed crosswise. It has rose- coloured flowers, and grows in similar situations to common heather. Flowers in July and August. Grouse do not seem to care much for the two last-named heaths. THE GROUSE IN HEALTH AND IN DISEASE Part II. — The Insect Food of Young Grouse based on AN Examination of Crops and Gizzards By Percy H. Grimshav; The Committee have devoted special attention to the question of the food of the Grouse in the earlier stages of its existence, and have examined the crop Variety of Contents of many chicks with a view to ascertaining the nature of their chicks diet, ^jg^ Their dietary is extraordinarily varied, and probably we have as yet by no means exhausted the list of what they eat. It was observed from Insect food *^^ commencement of these investigations that young Grouse were common, much more addicted to insect food than were the adult birds, and in order to complete the Committee's knowledge on the subject it was found advisable to obtain the services of an entomologist. In the months of June and July 1908 the moors in Inverness-shire, Morayshire, and Banffshire and at a later period also in Yorkshire, were visited with the object of investigating the food of the young Grouse. (1) In the first place it was desirable that a number of young Grouse chicks should be obtained, and the contents of their crops and gizzards examined, with a view of ascertaining both the nature of their food, and also, if possible, the intermediate host (supposed to be some insect or mollusc) of the Cestode parasites which infest these birds. (2) To exactly determine the various fragments found in the crop, pro- ventriculus, and gizzard of Grouse by the careful collecting of insects on the feeding grounds of the young birds. In many cases the remains in the crop or intestine were so broken up and crushed that it was only possible to determine and name them by careful comparison with whole specimens obtained on the same spot.' (3) To collect and put into spirit large numbers of insects and spiders for the purpose of dissection and microscopic examination for possible cysts of tajieworms. The list of insects collected was most interesting, and included many rare ' a complete list of the insects obtained on the moors during the course of this Inquiry has been published in the "Annals of Scottish Natural History," pp. 150-162, July 1910. THE INSECT FOOD OF YOUNG GROUSE 89 species. Unfortunately, owing to broken weather, working with the net was only possible on six days, otherwise the list would have been even Ljstsof more representative. Most of the specimens were collected on the '°''<^^*'^- actual feeding grounds of the young Grouse, and the list is therefore useful as showing the variety of diet possible during the first fortnight or so of the chick's life. On a typical Grouse moor by far the greatest variety of insect-life is found in the marshy ground around the sources of the streams. In every such place the entomologist, by using the sweeping net, finds an abundance of specimens and a fair variety of s^Decies. Diptera largely preponderate, but small Tineid Moths, May-flies, Stone-flies, and Spiders are also plentiful. On the higher and drier ground many other insects occur, including Crane-flies, Bees, and the larger Leindoi^tcTa, as well as a few others which must be regarded as of mere casual occurrence, such as Syrphidce or Hover-Hies, the Bomhus or Humble- bee, etc. In Appendix E will be found a detailed list of the contents of the crops and gizzards of forty - five chicks examined. The birds were captured by hand and immediately killed by chloroform, dissected the same day, and their crops and gizzards transferred to methylated spirit. The contents of both crops and gizzards were afterwards examined, and the fragments carefully compared with whole pinned insects obtained on the same ground as the chicks. In many cases the remains were so crushed and fragmentary that it was impossible to ascertain their nature, beyond the fact that they were Coleopterous, Dipterous, etc. Where the generic and specific names are both given, it may be assumed that the identification is certain. The commonest insects in the crops are undoubtedly Diptera of the family Limnohiidrt. Seventeen crops contained specimens that could be referred to this family, and of these no fewer than fourteen contained the curious insects little species known as Molophilus ater. In one case (that ticketed J^ioniy""' Moor, No. 2-22) there were over one hundred specimens of this Hy. <"**®"- According to Dr Wilson's estimate this bird would be from eighteen to twenty days old, and its crop was gorged with the remains of Molophilus ater, and contained also two other Limnohiids, besides a few tips of heather. Other crops from the same moor, belonging to chicks a week old or less, contained fifty-six, fifty, thirty-four, and eleven examples respectively of the same fly. 90 THE GROUSE IN HEALTH AND IN DISEASE We may therefore conclude that the species is attractive to the eye and taste of the young chick. It was found plentifully in certain marshy spots where the chicks were known to feed. Although the results have been tabulated in various ways, it has been found difficult to trace any outstanding feature regarding the insect food of Grouse chicks. With such a small number of birds it would be manifestly unwise to work out averages and curves. It is sufficient for the present purpose to show that the food of young Grouse is largely made up of insects, that these insects present a great variety of species, and that the species most commonly found in the crop is probably that which is most numerous in the area where the chicks are accustomed to feed. But it is also evident Insect food that the number of insects eaten shows a considerable falling off after'third towards the third week of the chick's life. We should not expect week. ^jjg chicks to show much discrimination in the catching of their prey, and as Diptera undoubtedly are the most numerous in individuals of all the insects on the moors, it naturally follows that they head the list in the table of crop contents. In the Table (p. 91) an attempt has been made to indicate, in somewhat more graphic form, the results of the examination of the crop contents. The crops are arranged, so far as possible, in order of age, beginning with the youngest. The ages of the birds are estimated by the length of the keel of the sternum or breast-bone. Relatively the ages are believed to be sub- stantially correct, though individually there may be a discrepancy of three or four days. The sign x in the Table indicates the presence of remains in the crop belonging to the order of insects named at the top of the column. In the third column the solid black o shows that no insect remains of any kind were found. This Table is of special importance as showing the extent to which the insect food falls off after the second week of life. This is also borne out by the great drop in the number of orders of insects represented by the crosses. The crops of young chicks in the first week or two have been found to contain, in addition to insects, the following vegetable food-stuffs in Vegetable . ' . ' 6 6 food of varying proportions : — chicks. Calluna shoots ; only the very fresh j^oung green shoots are eaten. Calluna flowers, in full bloom, and flower-buds. THE INSECT FOOD OF YOUNG C4R0USE 91 Table showing Proportions of Animal and Vegetable Food eaten by Young Grouse. o 6 £ ll ¥ O U K a ** INSECT FOOD. VEGETABLE FOOD AND GRIT. • ■q X X X X X X X X X t o 1 1 o » s H 1 s 15 'S -g g ■< i a a i §• 3 1 B i! CO B a .5 S a g i a V 11 m ■i 5 D. 10 D.21 1 D. 12 D. 23 » T. 1/ D. 16 T. 21 D.26 D.15 T. 3 D. 181 D.2a I D.isj D.20 9-75 10-50 10-75 11-00 11-25 12-00 12-25 13-00 13-25 0 {I (X \o X [1 X 0 {I X 1st week — 1 to 7 days old X X X X X X X X X X X D. 9\ D. 5/ D. 4 D.141 D.19/ D. 21 D. 3/ D. 71 D. 1 D.25 J T. 41 D.17/ 13-50 14-50 15-00 15-25 15-50 15-75 1^ Ix X fx \x fx \x u fx lo X X X X X X X X X X X - X X 7 to 18 days old X X X X X X X X X X K X T. 12 D. 2 B. 31 T. 5/ 16-00 16-50 17-25 0 X fo \o X 18 to 20 days old X X X X • X T. 9 T. 101 T. 8 / D. 8\ T. 7/ T. 6 20-75 22-75 24-75 26-75 0 ll /x Ix X X X X X X X X X X 20 to 28 days old X X X X X X X X X B. 6 T. 11 E. 1 27-75 28-25 3000 X 0 X X X 28 to 30 days old X X X X B. 2 B. 5 34-00 35-50 X X X X • 35 to 40 days old X X J B. 4 36-50 X 1 X • 6 weeks X B. 1 44-00 X X X 6 to 7 weeks X X ■ 92 THE GROUSE IN HEALTH AND IN DISEASE Moss fruit-capsules, or spore cases. Blaeberry flower - buds, and ripe blaeberries occasionally ( Vac- cinnim myrtillus). Blaeberry leaves and young stalks. Fern leaves {Blechmcm and Pteris). Rush heads, in flower and seed {Juncus sq.). Tormentilla seed-heads. Shoots of Empetrum nigrum. Of these the most constant are the fresh young shoots of Calluna ; then the fresh blossoms of Calluna, and then the spore capsules of moss. While insects are commonly eaten, many crops of the youngest chickens contained no trace of them. It is practically certain that by eating some such animal food the cystic stages of the intestinal worms which infest young birds even in the first weeks of their existence are introduced. Until this matter has been further investigated, it is needless to say more here. Part III.— Water By A. S. Leslie There are various opinions regarding the Grouse's requirements in the way of water. The majority of moor-owners and naturalists are firmly convinced that Grouse do drink, and quote in support of their view the undoubted believed fact that when springs and drains are periodically cleared the stock is that Grouse , „ , , ^ i ^ i ■ ^ drink more healthy and numerous. Others state tliat water is not necessary, and that the fact that drains and springs are not allowed to become choked may have beneficial results apart altogether from the maintenance of the water supply. The evidence on the subject is somewhat conflicting. As already stated. Grouse do not appear to require water from springs or burns in the earlier stages of their life ; ' this fact is established from observations on both wild and hand-reared birds. On this subject, a well-known moor- owner in Banftshire writes : " Grouse never seem to want water except in a very dry season ; a shower is sufficient to last them for a long time. The less water they have in hand rearing, T find, the better they do." And, again, " I have never noticed that the young Grouse, when half-grown or older, ' Vide chap. ii. j). 18. WATER 93 require more water than what they pick up in the grass in wet weather, and what is sprinkled on the grass or heather at meal times in dry weather. Old Grouse seem to know how much is good for them ; while young Grouse, if allowed access to water, are almost certain to drink too much, and scour. This, of course, refers to tame birds." Another correspondent of the Committee, a gamekeeper near Pitlochry in Perthshire, writes: "Regarding water, I have known several broods fetched out 600 yards from the nearest water of any kind, in a dry season, and they continued to thrive without water for at least three weeks after hatching, when rain would no doubt relieve the old bird, which I am of opinion had nothing to drink but dew all that time ; at least I never found youug chicks without the parent bird along with them." On the other hand, a gentleman in Yorkshire, who successfully reared twenty-four Grouse out of twenty-eight eggs set, says: "They were watered three times a day." And a gamekeeper, whose experience of some of the largest moors in Perthshire has lasted for a lifetime, says: "There must be water, and, where a moor is blest with good springs, there will the Grouse be also. One cannot have too many springs on a moor in dry weather." When full-grown there is little doubt that Grouse do drink ; hand-reared birds are seen to drink frequently on a hot day from the supply of fresh water provided for them, and the droppings of nesting birds are always found Evidence near water. Wild birds, in the hot weather of July and August, and in o'f G^oTse the dr}', frosty days of winter, often congregate near running water and "'"'"S- open streams when other drinking-places are dried up or frozen hard. It is well known that in the summer Grouse often shift entirely from the drier beats of a moor to the well-watered ones, and, on a certain dry, sandy moor near the sea, the young birds die if the artificial drinking-pools are allowed to run dry. The almost unanimous opinion expressed by correspondents favours the view that under natural conditions the adult Grouse go to drink two or three times a day. In support of the view that Grouse either never drink, or at least are not dependent upon a supply of drinking water, several arguments are brought forward. It is said that no Grouse has ever been seen to drink, but Arguments when we consider how wild the bird is in its natural state this is not Arouse do surprising; indeed, only very few observers have succeeded in seeing "otdnnk. the bird in the act of feeding. Another argument used is that from an examina- tion of the alimentary canal no trace of water can be found, and the contents 94 THE GROUSE IN HEALTH AND IN DISEASE of the crop are always found to be dry. This may be sufficient to prove that the bird does not drink wlien the crop is full, but does not dispose of the possibility of its drinking during the long periods of the day when the crop is empty. Then, again, cases are quoted of moors which carry a large and flourishing stock of Grouse where the ground is by no means well watered. On one of the best stocked Grouse moors in Britain, the only water comes from about a dozen springs and one deep burn which runs through the middle of the ground. Grouse are seldom observed to resort to the burn, and it is difficult to see how several thousand birds can all water at the springs. While it cannot be said that this entirely disposes of the water drinking theory, it seems to justify the view that Grouse are not dependent upon a large water supply. How far dew forms a substitute for water is a matter which the Committee consider of great importance, and one to which they have given considerable attention without arriving at any results sufficiently definite to be worth reporting. There is a curious lack of information available regarding the fall of dew, the districts in which dew is most prevalent, etc. There is probably a close connection between dew and the infection of Grouse by the nematode worm Trichostrongylus pergracilis. In view of the fact that the larva^ of this worm can only climb the heather shoots, or indeed exist on them, when they are slightly damp, the Committee believe that this is one of the questions which might be further investigated with advantage.^ Part IV. — Gkit By Dr H. Hammond Smith and R. H. Rastall The health of Grouse and of other game-birds is greatly dependent on the nature of the grit they take to assist in the assimilation of their food. Necessity During the autumn of 1906 the Committee made a collection of the of grit. grits from the gizzards of Grouse and other game - birds. This collection formed the subject of a paper read by Dr Hammond Smith at Collection '^ meeting of the Zoological Society in May 1907. These grits were Coni*? ^^ obtained from the gizzards of Ptarmigan from Ben Mohr in Sutherland- mittee. shire ; Grouse from Ross-shire, Inverness-shire, Aberdeenshire, and ' Vide chap. x. pp. -228, 233. GRIT 95 North Wales ; Blackgame from Eoss-shire and Exmoor ; and Partridges and Pheasants from various counties in England and Scotland. The gizzards of Grouse naturally received most attention ; but for purposes of comparison those of other game-birds were also examined. The quantity of grit found in a single gizzard varies very slightly. Samples taken g^jj^ ^^ from adult cocks were each found to be equal in bulk to an ounce of ^'e/X'^'^ shot, although, of course, much lighter, and the number of grains in g'^^a^d. each ranged from three hundred and fifty to five hundred and fifty. It was also noticed that, especially in the case of Pheasants, the cock birds have a larger quantity of gritty material, while the individual grains also appear to be larger. This is doubtless correlated with the larger size of the gj^g ^f „J.■^^^ bird, for in the smaller varieties of game - birds and in immature P'^'t'cies. individuals it is invariably found that the grains of grit are fewer and smaller than in the larger and full-grown specimens. The gizzard of a chick of fourteen to twenty days old was examined, and the grit was found weio-htof to weigh 3 grains. It consisted of fragments of quartz, smooth ^''''^*^' and water-worn, and evidently picked up in the bed of a stream. 2\vo only were minute but perfect prisms of quartz, quite unworn. All the grains were decidedly smaller than in an adult. In a half-grown chick the grit weighed 58 grains, while in adults the average weight is 118 to 120 grains. Grits are present even in very young birds ; in one case they were found in a chick only forty -eight hours old. The grit of an old bird can be at once recognised by the large size of the grains, and by the excessive polish and smoothness of the well-worn surfaces, suggesting that the larger grains are in use for a considerable period of time. Between extreme youth and old age all stages of wear and polish may be found as well as every gradation in point of size. A full analysis of the petrological character of the specimens is contained in the Interim Report of the Committee ; it is unnecessary to repeat all the details here, but a short summary of the general conclusions may co^gtitu- be given. As would naturally be expected the constituents of these *^"tsofgnt. samples are nearly always hard rocks and minerals. Minerals or rocks softer than quartz, flint, or felspar are hardly ever found ; this may be due partly to selection by the bird, but it must also be borne in mind that soft substances would soon be ground up by the action of the gizzard, and disappear. To this also is probably due the almost complete absence of any calcareous matter, 96 THE GROUSE IN HEALTH AND IN DISEASE which is both soft and comparatively soluble. The only really abundant constituents in the gizzards of Grouse are quartz and felspar, and small fratrments of various rocks composed of one or both of these minerals, such as granite, gneiss, quartzite, etc., with occasionally grains of shot and crystals of garnet, and other minerals. Felspar is chiefly found in specimens from Scotland and North Wales, where rocks consisting largely of this mineral are specially abundant. The specimens from Ross-shire are of interest from the o-eolowical point of view, since in some cases they contain a representative collection of the gneissose and schistose rocks of the north-west Highlands. A comparison of results shows that in the gizzards of Grouse quartz is nearly always present, although no quartz may be found on the moor where the bird was shot. Two cases of this may be mentioned. On one part of an exten- sive shooting in North Wales there is excellent feeding and sheltering ground for Grouse, but no quartz grit, yet the gizzards of the birds always contain quartz ; in order to obtain it they have to fly across a wide valley Quartz j.q another hill, and then return again to their feeding - ground. present in ^ a a gizzards Ao-ain, on a Ross-shire moor no quartz could be seen on the moor, thouf^li not o ' found on yg^ ^11 the gizzards of these birds contained quartz; it was found that moor. -^ ° 1 c 1 1 r • • this quartz was probably obtained from the burns, for on examining them small pockets of water-worn quartz were found in many of the pools and eddies. The quartz is not always angular and sharp, but is frequently water-worn ; in these cases it is probably picked up out of burns — in fact, in low-lying moors the water-courses are almost sure to be the source of this quartz. The writs found in the gizzards of Yorkshire Grouse are very similar to those of the Scotch birds except in one case, where the grit is chiefly composed of small black pebbles. In one gizzard out of every three of the Grouse examined shot were found ; but shot were rarely found in the gizzards of Pheasants. The mineral contents of the gizzards are very fairly representative of the harder rocks and minerals of the district from which each is derived, but it may be noted that whereas Ptarmigan and Grouse seem and " ^^^ unable to exist without quartz, Partridges, and still more Pheasants, are more adaptable ; they prefer quartz if they can get it, but failing quartz. Pheasants will content themselves with flint, sandstone, and even coal. Doubtless the tough and fibrous nature of the food eaten by Grouse GRIT 97 makes it necessary for him to confine himself to the hardest and most angular descriptions of rock, and even when quartz grits are found in the gizzard the angles are often rounded and smooth from the nature of the work which they have been called on to perform. Flint grit may serve for Pheasants, but it does not fracture into serviceable shapes for Grouse. Sharp points and cutting edges are not wanted, but sub-angular and roughly rounded pebbles of small size for the breaking up and pulping of the comparatively hard foliage of Calluna. In another part of this Report it is suggested that when quartz is scarce it might be artificially introduced with a view to the welfare of the stock. This expedient has met with some success, but has not been very Artificial extensively adopted. The artificial introduction of quartz grit has tion°of'^ frequently been tried with Pheasants, and always with success. In the ^"'" Committee's collection there are several specimens of gizzards from Pheasants shot on estates both before and after the introduction of quartz, and in every instance it can be seen that the quartz is preferred to the natural grit found on the estate. Observations have been made with a view to finding out how long quartz or other hard grits normally remain in the gizzard of a Grouse, and it has now been proved by experiment that if none are supplied to make . good the normal and presumably accidental loss, the bird whose during . •- ■' which gizzard may on the first day have allowed about a hundred grits to g"ts , ,. „ . remain pass, becomes exceedingly careful on the second and third day, and i" the gizzard. allows no such loss to occur again. In a case in which no grits were supplied to a Grouse at all, and in which the grits passed in the droppings were carefully washed out and collected every day for twenty-one days, the greatest daily loss after the second day never exceeded thirteen small pieces, even though a hundred and sixty pieces had been passed on the first day, and twenty-seven pieces on the second. This bird died unexpectedly on the twenty-first day, and upon dissection the gizzard was found to contain still no less than half of the original contents, all of which over waste of grits. had been in the gizzard for at least three weeks. That this apparent control of the gizzard over the loss of grits was not merely accidental was proved by the occurrence of a precisely similar series of losses day by day in another bird ; but when its companion died, apparently as the result of losing half its grits, the second bird was not pressed to a similar finish.' It is therefore probable that in the ordinary course of a Grouse's life the 1 For detailed description of experiments in Grit Starvation, see vol. ii. Appendix F., part (1). VOL. I. G 98 THE GROUSE IN HEALTH AND IN DISEASE daily loss of small grits is considerable, and that this loss is replaced by an equally regular supply picked up day by day upon the sides of moor roads, or in " scrapes," or along the channel of a burn. But, in the event of a heavy snowfall it appears very probable that the Control Grouse soou recognise that the loss is exceeding the amount which Sme'of" ^^^ ^^ made good day by day, and that in such a case they can, snow. jjj some unexplained way, place a check upon further loss. It cannot for a moment be imagined that the bird has any sort of voluntary control over the passage of grits from the gizzard. But it is quite conceivable that the gizzard itself will allow a certain careless loss of any surplus number, especially of the smaller pieces, so long as there is still a sufficiency of larger grits in the gizzard. When the supply, however, is straitened, and the bird fails to find more grits to swallow, it may be that less food is eaten as well, and thus the loss of grits is automatically reduced. This is probably the explanation which comes nearest to the truth, and it is a significant fact that a bird not only loses weight, but may actually die when only half of its normal supply of gizzard grits has been lost, and when the dejecta show that this amount of grit is still capable of grinding up the food given to it. Under normal conditions the character of the grit required difi"ers with the nature of the food that is being eaten. With hard grain or seed, or with berries containing seeds, it is badly needed, and must be obtained if the food is to be digested. Oats and oat husks are all efficiently dealt with by the quartz grit normally found in a Grouse's gizzard, but large hard seeds are not, and are passed undigested. These seeds, however, are sufficient in themselves to pulp fruits so long as fruits only are being eaten. But as soon as heather or other fibrous vegetable matter is eaten, quartz or other stone grit becomes essential. The possibility has been suggested that the replacement of quartz grits by hard seeds of fruit, and the passage of the former through the intestine may act as a vermifuge. So often has a diet of berries apparently Berry seeds r tt i ■ i • • i • • • i • i as a vermi- arrested a case of Helminthiasis that it is a question to be seriously fuge. • J J 1 1 considered whether enough attention is given to the encouragement of berry-bearing plants upon a moor. In many cases the sheep keep them so closely cropped that except where there are woods or enclosures it is difficult to find a visible trace of them. It would perhaps repay the trouble GRIT 99 and expense to fence off enclosures from the sheep where any tendency is seen for the growth of Blaeberries, Cranberries, Crowberries, or the like, and the Grouse would quickly find and make use of them. No. 1215 may be cited here as a case in point, for the bird was an obviously convalescent hen Grouse of 16 ounces, with every sign of excessive Helminthiasis, but a complete absence of Davainea, and only one or two portions of Hymenolepis. Trichostrongylus alone was present in great numbers. The gizzard contained no quartz, but was full of hard seeds (cluster- berry or Vaccinium Vitis-idcea). The small intestine, full of food, was very irregularly contracted, and contained not only many unbroken clusterberry seeds, but quartz grits as well, while the rectum contained the same, and exhibited a considerable amount of punctiform, villous reddening, especially in the lower third. Grouse No. 1228 was a rather similar case, the gizzard being crammed with hawthorn seeds, and having no quartz at all, while the small intestine was very much irritated, had its vessels all fully injected with very fluid contents, and yet no Davainea at all. The rectum w^as again red with injected villi. This bird was caught sick. It was a case of Strongylosis in a hen of 13 ounces only. In the Blackcock the gizzard with its quartz pebbles can crush hawthorn pips, but the Grouse apparently cannot crush any of the pips or even much smaller berries such as Clusterberry, Blaeberry, or Crowberry. They all pass through intact. Nos. 1265, 1723, 1733, 1735, 1817 are all cases in point. It is particularly unfortunate that during deep snow, when Grouse have great difficulty in replenishing their stock of gizzard grits, they are compelled by hunger to feed upon the very foods which most rapidly evacuate their entire stock of grits. The hips and haws whose large hard seeds, as has been said, quickly replace the quartz in their gizzards, are comparatively useless to them for dealing with heather or Blaeberry shoots, yet the bush and tree fruits are amongst the first emergency rations used in a heavy fall of snow, since they come within reach as the ground foods become more deeply buried. The strongest evidence that quartz is the most suitable form of grit is its universal presence in all the vegetable feeding birds that can obtain it. Red Grouse, Ptarmigan, Blackgame, and Capercailzie, as well as Pheasants and Partridges bred on the moor borders, and Scandinavian Willow Grouse, all collect quartz, and nothing but quartz, if it is by any means to be obtained. CHAPTER V PHYSIOLOGY AND ANATOMY OF THE EED GROUSE By Edivard A. Wilson As a preliminary to the proper understanding of the method of infection in the Object of forms of "Grouse Disease" known respectively as Strongylosis and chapter. Coccidiosis certain facts concerning the functional activities of the different parts of the Grouse's alimentary canal should be explained. By the alimentary canal is meant the whole tract of the digestive apparatus from the mouth, to the anus or vent ; and the following is briefly a canal de- history of the experiences undergone by a morsel of food after it has been swallowed by a healthy bird. In the case of the Grouse it is reasonable to take a small sprig of heather, Calluna vulgans, with a somewhat woody stalk and a number of very small Character greenish or brownish green leaves, and perhaps a few small pink eatenby Aowers or shrivelled flower heads containing a considerable number Grouse. ^f very small seeds. Other foods of course are frequently eaten, but all the vegetable stuffs may be considered as partly composed of soft, alterable, and digestible material, such as starch, protoplasm, chlorophyll, and sap solu- tions, and partly of indigestible woody fibres. The animal foods, whether they consist of insect or mollusc, worm, crustacean or spider, can also be considered as composed partly of soft, digestible material, and partly of indigestible matter, such as chitin. And further, the function of the grit must be considered, since it is as essential . to the well-being of a herbivorous or graminivorous bird as are teeth to the higher mammals. The sprig of heather is partly plucked, partly cut from the growing plant by the beak of the bird. In captivity it is found necessary to fix the bunches of heather either by tying them to the wire run or bv placing a heavv weight upon 100 PLATE XXVI. E Wilson, Cambria u, Opposite p. 101.] PHYSIOLOGY AND ANATOMY OF RED GROUSE lOl clie roots ; should this precaution be neglected the bird, having no notion what- ever of using its feet to steady anything, drags the loose heather all over the ground in unsuccessful efforts to pluck off the tips. There is sometimes to be seen quite a free flow of watery saliva from the beak of a feeding bird, and in the mouth of birds killed there is always a certain amount of saliva. This saliva serves to coat the rough hairy heather , , Saliva. tip with mucus, and thus to facilitate its passage down the oesophagus to the crop (Pis. xxvii.a, XLiv.). The food is, of course, swallowed whole but in very small pieces, and there is no mastication. The length of the oesophagus (Pis. XXVI. oe., XXVII., Fig. 1 (a), xliv.) from the pharynx to the proventriculus is 5| inches ( = 140 mm.), when the neck is normally outstretched; q, , but before passing down the whole length of this tube the food finds S"^- its way into a thin-walled sac or diverticulum of the oesophagus, at a point 3 inches, or 75 mm., from its entrance at the pharynx, and commonly called the "crop" (Pis. xxvii.a, xliv.). Here the food collects, and Crop. remains for a longer or a shorter period according to the rate at which the gizzard can dispose of it. The latter portion of the oesophagus measures 2 inches ( = 50 mm.), in length, and the opening of the crop occupies about 17 mm. of the front wall of the oesophagus. The proventriculus p,.oveji. (Pis. xxvi. Pr., xxvii., Fig. 1 (b), xliv.) forming the thick- walled t"'^"!"^- glandular part of the stomach has a cavity of very small dimensions, and a length of f inch ( = 20 mm.). It is lined with large mucous glands having prominent mouths. These secrete a thick, tenacious, opaque white fluid, where- with the morsels of food on their passage from the crop to the gizzard are coated. In this respect there is a very great difference between the condition of the food as it leaves the crop, and its condition in the actual gizzard. In the crop the food is almost invariably dry, almost exactly as it is plucked from the living plant, and it is found thus in masses fresh and green, or greenish brown, with no appreciable admixture either of mucus or of water. This almost universal dryness of the heather, or other Grouse food, as it is found in the crop, militates strongly against the idea which is Foodiu occasionally suggested that the Grouse is a thirsty bird by nature, nOT^^aHy and must have an abundant supply of water. This is almost certainly ''''^'• not the case, for the very rare instances in which the contents of the crop 102 THE GEOUSE IN HEALTH AND IN DISEASE were found distinctly wet, were, without exception, in birds showing definite signs of sickness, and in sickness there is no doubt that the bird Drinking , . . . -i i i. habits of secks Water and often drinks it. It is, however, very possible that water is swallowed straight into the proventriculus, passing by without entering the opening into the crop. If this be so, too much stress must not be laid on the dryness of the food in the crop, in considering the drinking habits of the bird. But with food in the crop, and there is no hour in the day when the crop may not contain some food, all the evidence afforded by an examination of many hundreds of crop-contents goes to prove that water is not freely taken, or if taken, is not admitted to the crop. Probably, when there is food in the crop, no water is drunk, for there is no general condition of wetness at any time either in the crop or in the proventriculus, or in the gizzard, all of which are occupied in turn by the gradual passage downwards of the morsels of food collected in the crop. In the proventriculus, as has been said, the bits of food, coated now with a tenacious and slightly acid mucus, are passed into the muscular gizzard (Pis. XXVI. (g.), xxvii., Fig. 1 (c), xxvii.a, xliv.), a familiar object Gizzard. . .... m the anatomy of the common fowl, and an organ oi very similar shape and of equal muscularity in the Grouse. Its walls are very thick, and the muscles which compose them act from tendinous sheets, into which they are firmly fixed. The cavity of the gizzard is comparatively small, and is lined with a very tough resistant lining membrane of fibrous tissue, and contains about a teaspoonful of small hard subangular or rounded grains of hard rock. The substance almost universally chosen by the Red Grouse is quartz, and although on the moor, as in captivity, the bird will swallow any small portion of hard material which comes in its way, quartz is most suitable, not only for the Grouse but for every other graminivorous bird in health. A very extensive collection of Grouse's gizzard grits has been ^ , made by the Committee, and carefully examined, and the result Quartz •' ' J ' most shows the variety of material of which a Grouse will make use when common. _ •' quartz is not locally abundant.' But the point conclusively proved is that quartz, both on account of its hardness and its method of fracture, is the gizzard grit most abundantly used by Grouse. The subject of gizzard grit is more fully dealt with in chapter iv. ' Vide chap. iv. p. 9.5. PLATE XXVIl. (a)- Fig. I. -J !^^ P \ ^^ Fig3 Ac) (i) a) Ih) Opposite p. 102.] PLATE XXVIlA. /!:i=^ -;» \ h A % x^ Carotid Brachial Aorta — Left Auricle Right Auricle Right lobe of Liver '^ lii ■^Left do Apex of Gall Bladder Gizzard " Pancreas Caeca Caeca ./•■ ^^) E Wilson, del el hth Cambridge Oi>posilep. 103.] PHYSIOLOGY AND ANATOMY OF RED GROUSE 103 Lead pellets are often picked up by the bird amongst other objects, and swallowed because they are hard and small ; but the suggestion •^ ' =>» Lead that lead poisonine; has ever resulted either in this or in any other pellets in ■- . gizzard. way from the scattering of leaden shot over a moor must not be taken too seriously. The food then having reached the gizzard with a free admixture of slightly acid mucus, is now thoroughly mixed up with the grits of quartz, and ground with their assistance to a pulp, the harder woody fibres soon showing Action of up as whitish bits in a brownish, greenish, or reddish mess. This ^izzar . vegetable pottage has now to be separated from the quartz grits, and to be passed little by little into the duodenum. The separation is effected at the distal sphincter muscle of the gizzard, and it often appears as though the sphincter was unable to distinguish readily between the feel of a quartz grit and the feel of a hard seed, or the woody , . feeparatioii ' "stone" of a berry. It is by no means rare to find, when a bird has of food •1 T c • 1 1 • T ^''°"^ grits. been feeding for a time on berries or wild fruits, that the gizzard loses all its rock grits, and contains nothing harder than seeds, pips, or woody " stones." Concurrently with this, it is sometimes found in birds which, from their condition, one would have expected to have contained tape- worms in abundance, that the intestines below are entirely clear of these parasites. We are thus tempted to think that the passage of a Effect of number of quartz grits and hard seeds may have so stimulated the f"*fnto''^' peristaltic action of the intestine, and at the same time have so '"testme. damaged the tapeworms that the latter have been broken ofi" at the neck and discharged en masse. The worms may grow again from the attached head or scolex, but it is possible that even the scolex may in many cases be dislodged, and for that reason the advisability of encouraging such Grouse foods as have big seeds and hard berries has sometimes been advocated. Be this, however, as it may, the digestible food, including our particle of heather, now sufliciently pulped in the gizzard, is separated as it leaves the gizzard from most of the harder and larger grits, and enters the duodenal loop of the small intestine. The duodenum (Pis. xxvi. (c), xxvii.. Fig. 1 (d), xxvii.a, 1-2, XLiv., 6f inches ( = 170 mm.) in length, begins at the exit of the gizzard and is U-shaped. It consists of two parallel " limbs " of about equal length. These two limbs are supported and held together by a mesentery 104 THE GROUSE IN HEALTH AND IN DISEASE which contains the pancreas (Pis. xxvi. Pa., xxvii., Fig. 1 (e), xxvii.a, xxvni., Fig. 1 (e), XLiv.), a pale pink, flattened glandular mass filling the space between the descending and ascending limbs. This gland pours its alkaline and digestive pancreatic juice and ferment into the uj^per end of the descending loop. The liver (Pis. xxvi. (l.), xxvii., Fig. 1 (/), xxvii.a), also pours its alkaline, biliary secretion into the upper end of the descending loop, so that it is intimately mixed with the pulped food as it passes into the duodenum little bv Liver. little. The shape of the loop assists this admixture, since it checks the immediate passage of the contents into the convolutions of the upper small intestine. Digestion is now ready to go on apace. The food, when being macerated and pulped in the gizzard, is distinctly acid ; but, when mixed with the alka- line pancreatic and hepatic secretions from the liver, becomes cri-adually Chemical ^ . ... . o J action of neutralised until it is of the right reaction as well as at the right digestion. r ■, • r ^ t c temperature for the action of the digestive ferments.^ In the duodenum the contents are normally almost fluid, when there arc no tapeworms or threadworms present. The duodenum is, however, the common habitat of Hymenolepis microjos, and of Trichosoma Parasites i ■ ii ■ tic fi •<■ found in longicollis ; and the former of these is frequently present in such duodenum. ' . ,. , large numbers as to appear like a soft, semi-sohd, creamy mass completely filling the whole length of the duodenum (PI. xxviii.. Fig. 2). It is only when this worm is absent, as it generally is during the winter months, that one appreciates the fact that the duodenum seldom contains at any one particular moment more than a very small amount of solid food pulp mixed with the digestive fluids. The passage of the food through it is very gradual, and the admixture with the alkaline digestive juices is proportionately complete. Normally the outward appearance of this part of the intestine is a pale creamy white, and the mesenteric vessels which ramify over the peritoneal surface are almost invisible. The pancreas also should be pale creamy white or faintly pink (PI. xxviii., Fig. 1 {a) (e) ). The alkaline mixture now passes from the duodenum into the convoluted upper portion of the small intestine (Pis. xxvi. (c.s.i. ), xxvii., xxvii.a, xliv., Small Fig- 1 (,V))- This extends from the lower end of the duodenum to intestine, ^j^^ ^^^^^^^ ^^^ ^£ ^j^^ rectum (Pls. XXVI. (r.), xxvii.. Fig. 1 (A) xi.iv.), ' Vide pp. 105, 106. PLATE XXVIII. E Wilson, Cambridge. Opposite p. 104.] PHYSIOLOCIY AND ANATOMY OF RED GROUSE 105 where the two cseca enter it. The small intestine measures in all 35 inches ( = 872 mm.); but there is a distinction to be made between the upper or proximal convoluted portion which is attached to a wider mesentery, and the lower or distal straighter portion (PI. xxvi. s.s.i.) which is attached to a much narrower mesentery. And, while there is probably a difference in the character of the glands which form the mucosa of these two portions, the chief obvious distinction is that the convoluted portion is freely moveable, whereas the straight portion is so intimately folded with the long csecal appendices, and so closely bound together with them in a common mesentery as to be very limited in its movement. The various parts of the lower intestine are shown laid out in the accompanying diagram (PL xxvi.), while the next diagrams shows them as they appear in their normal condition in the body cavity of the bird (PI. xxvii., Fig. 1, xxvii.a). Returning, however, to the changes which are being experienced by the particle of food in question as it passes from the duodenum into the convoluted portion of the main gut, it is first noticed that the accompanying duodenal tapeworm, Hymenolepis microps, wholly disappears, and that its place is taken by the much larger and more conspicuous tapeworm, Davainea Large urogalli, often in such quantity that the outward appearance of the t^P^'^^'O""- small intestine is altered to a swollen, bulky gut of a creamy white colour due to the enclosed mass of tapeworms shining through the thin and distended walls. Another point has already been noticed, namely, that the neutral or faintly acid reaction of the contents of the duodenum now gradually changes to a more and more markedly alkaline reaction. Hymenolepis aifects a neutral medium, and Davainea an alkaline medium. These changes in the character of the intestinal contents can, of course, be easily tested by the use of litmus papers ; but when a Grouse, which has been feeding upon ripe Blaeberries, Cranberries, or Crowberries with coloured juices, is examined, the contents of the alimentary canal of the bird itself are found to be coloured within from end to end, in such a way as to make litmus unnecessary. The juices of the berries are red, and stain the tissues red wherever the acidity is not overcome by alkaline digestive juices. But wherever there is a slight alkalinity in the juices there the tissues are stained bluish. This is shown in the accompanying figures, which are drawn directly from the dissection of a berry- feeding Grouse (see PI. xxvii.. Figs. 2, 3, and 4). 106 THE GROUSE IN HEALTH AND IN DISEASE Fig. 2 shows the food contents to be blue while in the proventriculus (alkaline), on reaching the gizzard (acid) they change to reddish purple, in the duodenum (slightly acid to neutral) they lose much of the red tint, but it is not until they enter the small intestine (alkaline) that they again resume the blue colour {see Fig. 3, representing one of the coiled loops of the .small intestine), the alkaline reaction continues throughout the length of the small intestine as far as the lower end of the rectum (Fig. 4 (A)), where it becomes slightly more acid, and the acid reaction of the caeca (Fig. 4 (?')) also causes the colour to change to a reddish tone. In the convoluted intestine the food is in a somewhat fluid state ; and as the mere presence of convolutions in the intestine of any animal are evidence of the necessity for a retarded passage, the function of the convolutions Reason for _. ... . convoiu- in this case is obviously to hold the mixture for a sufficient length of tions. . . .... time at a certain regular temperature m order to give the active digestive ferments every chance of completing their work upon the food-pulp. The heather-pulp is thus altered, so far as its alterable part is concerned, into a solution of assimilable food and an indigestible refuse of woody fibre. The raw material here becomes the digested material ready for use by the tissues of the body as soon as it can be brought to them by the agency of the circulating lymph and blood. Certain harmful and poisonous products will also unavoidably Elimina- appear in the Grouse's intestine as they do in the human intestine and *'°/^ °f„„„ in the intestine of every livincr animal from time to time, even in the poisoiiuLis ^ O ' food. ordinary course of digestion. These, as in the human body, having been absorbed with the soluble food supply into the blood are then eliminated, chiefly in their passage through the liver, before the mixture of good and evil products can be thrown upon the general circulation. The liver in man is the great eliminator of poisons produced in the intestine, and the liver in the Grouse almost certainly acts in a similar way. There is probably some selection and some chemical alteration during the passage of the food, including that part of our heather fragment which has now been digested, through the mucous membrane into the blood-vessels. By the time the food reaches the lower and straighter portion of the small intestine it is seen that much of the fluid has disappeared, the contents are becoming more and more thickened, and are now converted into a semi-fluid paste interspersed with woody particles. By the time that the contents reach the junction of the small intestine with the rectum they have been still further PHYSIOLOGY AND ANATOMY OF RED GROUSE 107 prepared for separation. At this point the ca3cal appendices (Pis. xxvr. cl, c2, XXVIII., Fig. 3 (i), xliv.) open into the main gut, and all that is soft is now squeezed into the narrow openings of the csecal appendices ; while all that is hard, including the indigestible part of the heather fragment, the indigestible woody fibres, and the refuse of the cellular tissues, is compressed into a firm, dry mass, and so passed straight into and along the rectum. Each caecal appendix measures from 30 to 36 inches (762 to 915 mm.) in length. Their colour in health is a dull drab grey, while that of the small intestine is greenish ; the diflPerence in colour between portions of the alimentary canal are shown on PI. xxvii.. Fig. 1, representing the normal duodenum (d), pancreas (e), small intestine (g), caecum (^). When excrement leaves the body of a normal healthy Grouse it does so in two distinct forms. The firmer excrement described aboA-e passing through the rectum leaves the body first, and either immediately, or after a Two forms of Gxcrs- short interval, the more fluid and pasty unabsorbed contents of the meut. csecal appendices follow without having mixed at all with the dejecta of the main gut. The dry and often quite hard Grouse " dropping," which outlasts much weathering, can be seen on many moors without any particular search, some- times at every yard or two upon bare burned ground, where it becomes bleached almost white under the combined action of sun and wind before it is broken up to be disseminated as dust. The matter is one of some importance, for the perfectly normal csecal dejecta of the Grouse are so often considered abnormal, and even pathological, by game- keepers and by sportsmen, and are so constantly credited with having some mystic relation to " Grouse Disease " that it becomes necessary to explain the appearances in detail. In walking over a well-stocked moor, in fairly dry weather. Grouse's droppings are to be seen lying in small heaps upon the ground where birds have "jugged" or roosted amongst the heather at night. It is sometimes surprising to see how many of these compacted rolls of undigested woody fibre are passed by a single bird in one night. Each hour throughout the roost there appears to be a separate motion, and always of the hard " formed " dropping coming directly from the main gut, and not of the pultaceous, soft, csecal matter. But, when morning comes, and especially when the bird has moved to the neighbourhood of water for the 108 THE GROUSE IN HEALTH AND IN DISEASE purpose of drinking, the ciBca discharge themselves, and the typical soft csecal dropping, which is so frequently misinterpreted as a sign of sickness, is then deposited either upon the harder dropping of the night if the bird has not already moved away, or more usually somewhere in the near neighbourhood. During the night the main gut and the cpeca appear to be engaged in a divided labour. While each ctecal appendix is employed in the absorption of nutritious, fluid solutions from the soft mass of food within it, the lower part of the small intestine is continually receiving from above more and more of the mixture of soft digested pulp and hard indigestible waste matter. The exact method of separation is due to the action of the sphincter muscles Method of which regulate the opening and closing, not only of the two entrances separation. ^^ ^^^^ cfecal appendices, but also of the entrance to the upper end of the rectum. There are no actual valves and no visible folds, but each caecum at its junction with the main gut is guarded by a narrow tubular portion (Pis. xxvi. cl, c2, xxvii., Fig. 4 (i), xxviii.. Fig. 3 (;')) some 4 or 5 inches (102 or 127 mm.) in length, which is lined by a mucosa rich in small projecting papillre, and which admits nothing to the caecum except the softer parts of the pulpy mixture. The pultaceous, creamy-brown pulp must be thus squeezed into these caecal back-waters by the peristaltic pressure of the small intestine from above, while the rectum at the same moment refuses to admit anything at all. Each caecum has one blind end and one end opening into the upper part of the rectum. All the useful contents of the main gut must j^ass into the caecum, and the undigested portion must pass out again by the same orifice. Yet the caeca always appear to be filled to some extent by material from one end to the other. It is only after a prolonged starvation, say for twenty-four hours or more on a railway journey, that the caecum is found in the condition represented Manner in PI- XXVIII., Fig. 3 (i), and it is obvious from this figure that the ciBcaare riddancc begins by contraction of the blind end, and that it gradually emptie . works toward the open end. It would appear from this that there must be a pause in the entrance of material to the caeca while they are evacuating the waste matter. The musculature of the small intestine seems thus to act intermittently but frequently, and without any long period of rest. The ctecal musculature, on the other hand, must have long periods of rest when the caecum is full or actively absorbing, and then a period of activity to empty itself. But these periods of rest and activity must be of very diflferent length. It is con- PHYSIOLOGY AND ANATOMY OF RED GROUSE 109 ceivable that after full feeding in the evening the Grouse jugs in the heather, and the process of digestion and the action of the intestine proceed until there is a large quantity of hard and soft food in the lower part of the small intestine ready for selective absorption and separation. This separation probably proceeds all night, the soft material constantly passing into the caeca, and the harder waste matter passing on as constantly into the rectum and out at the vent. Then, early in the morning the action is reversed, the passage of food down the main gut ceases because the supply from above has been stopped during the night when, of course, nothing has been eaten. The useful part of the csecal contents has now been absorbed, and is circulating in the blood, and the caecum therefore contracts downward and expels all the waste matter that is in it. This is borne out by what one sees upon the moor, by the absence of ctecal excreta amongst the heap of formed droppings passed in the night, and by the occasional appearance of some caecal excreta on the top of these heaps, though more frequently in their near neighbourhood or near the early morning drink- ing and feeding resorts. There is, moreover, now no doubt that the *= ° ' ' Feeding Grouse feeds more or less all day ; but, as a rule, the crop is found fullest times of Grouse. in the evening. Probably digestion is sufficiently rapid during the day to deal with the food almost as fast as it is picked and swallowed. It may be that the caecum receives matter both by day and by night, and discharges its contents only in the early hours of the morning ; but these details are not easy to determine in the wild bird, though it is easy to see how indispensable it is to the well-being of the Grouse that the caeca, whose combined length nearly equals that of the rest of the alimentary tract, and which are responsible for the absorption of most of its food, should be in good working order. It imjjortanc& seems impossible to exaggerate their importance in the bird's economy, °''''*°'*- for if they are put out of action the bird may eat as much as ever and yet rapidly lose flesh by sheer starvation. It may sutler even worse things owing to the decomposition of the food and the diminished powers of selection during Danger of absorption, thus causing toxaemia. That this happens is evident, for t<'-'^''e™ia. it is a very usual occurrence to find the caeca in a case of Strongjdosis, com- pletely filled by a semi-dried mass of foul, caecal matter adhering to the mucosa, leaving very little room down the centre for the passage of anything at all. In such cases the Tricliostrongylus is usually excessively abundant, and may Trkho- be seen bridging the space by hundreds between the adherent faecal mass ^''■™^ "*■ and the mucosa from which the latter is being forcibly separated in dissection. 110 THE GROUSE IN HEALTH AND IN DISEASE One portion of the alimentary canal remains to be mentioned, namely, the rectum (Pis. xxvi. (r.), xxvii., Fig. 1 (h), xliv.) This measures but 4|- to 5 inches ( = 115 to 127 mm.) from the point of entrance of the csecal appendices to the anus. The internal aj^pearance of the normal healthy rectum is shown on PI. xxix., Fig. 2 ; in this figure the dark staining about the csecal orifice is due to the proximity of the liver. The rectum appears to evacuate its contents almost immediately after receiving anything from the main gut or the cseca. When examined by dissection it is generally empty, or at the most but sparingly occupied by material ; but there is one marked exception to this statement. In the hen Grouse, during the laying of eggs and incubation, but especially during incubation, the want of exercise, and the necessity for keeping the nest clean, leads to an excessive accumulation of fasces, always of the harder, formed kind, in the lower part of the rectum. There is a great increase of size and of development in the ovary and oviduct in the breeding hen Grouse, and the rectum appears to accommodate itself to this. The ma-ssed and bulky droppings of a sitting hen Grouse, or "docker" as she is called, are well known to the gamekeeper as afibrding the most reliable and useful information he can have concerning the number of nests upon his moor. These droppings, due to want of exercise and the brooding instinct, result in an enlargement and distention of the lower part of the rectum and the cloaca, which recover themselves only after incubation and hatching are completed. As these bulky "docker's" droppings are only to be seen on the moor in the nesting season, it is perhaps not surprising that the keeper alone recognises what they mean. It is a very common thing for a keeper to congratulate himself upon their abundance along the side of every burn he comes to. Such places are used habitually by sitting hens when they leave their nests, perhaps once or twice a day, for food and water, and these droppings supply far more satisfactory evidence than could be gained by disturbing the birds on their nests. This then is, as briefly as possibly, the normal course of the digestion and Variations absorption of food in the alimentary tract of the Red Grouse, and digestive it remains now to speak of the more common pathological variations proce.ss. ^^^ disturbances which affect this process and which upset the health of the bird. PHYSIOLOGY AND ANATOMY OF RED GEOUSE 111 Many such variations have come to light during the past five years in the course of dissecting something like a couple of thousand Grouse : of these some were healthy and some unhealthy ; but in this chapter no account is given of lesions resulting from shot wounds or collision with wire fences or similar accidents. This subject is dealt with in another chapter.' By far the more important pathological changes which are to be found in the Red Grouse are those which result from excessive parasitism, and they are therefore discoverable as a rule in the intestines, and above all in the two blind csecal appendices, which afibrd a habitat to ^^Jmost'" thousands of the round - worm l^ichostrongylus ^Jer(7?•ac^7^"5. The factor**^"* particular csecal lesion, connected with this threadworm, and with the fatal Grouse disorder which is now called Strongylosis, will be dealt with separately.^ It will best serve the purpose in view to take again the alimentary tract from end to end, and to mention the lesions to which the various parts are liable.^ It is a very rare thing to find any disturbance in the upper reaches of the alimentary canal. The mouth, the oesophagus, the crop, the proventriculus, and the gizzard as a rule carry no entozoa, and are very seldom the seat of any pathological trouble. But it may happen that a bird gets hold of some irritant poison with its food, and this probably accounts for one or two other- wise unaccountable cases of inflammation of the crop walls, with engorgement and enlargement of all the vessels ramifying over it, and desquamation of the lining membrane (e.g., Nos. 1611 and 1759). In one bird (No. 1703) the crop contained plenty of fresh green Calluna tops, with Blaeberry leaves and bits of Fotentilla, mixed up with abundant legs of the crane fly, all perfectly normal and wholesome foods, but the wall of the crop was excessively inflamed, the lining ^uolTf™''" membrane shed, and a roughened surface was left exposed ; there was '^'^°^'' much fluid mucus, and all the vessels were injected and engoro-ed. There was also thickening of a granular appearance in the lower third of the oesophao-us ; but the mouth, throat, and trachea were all healthy. The mesenteric vessels were engorged and varicose, and the bird, which was a cock, and a bad case of Strongylosis, was infested with both kinds of tapeworm, weighed 15 ounces only, and was found dead. ' Vide chap. ix. p. 153 et seq. - Vide chap. x. p. 207. '■> Vide Diagram, p. 290. IVZ THE GEO USE IN HEALTH AND IN DISEASE Again, No. 1846 was a hen Grouse of 15 ounces only, found dead on May 6th, 1909, in Perthshire. This bird was very backward both in moult and in the development of the ovary. There was no attempt to put on the nestino- plumage. But the cause of death was an excessive Congestion i. x o of food in repletion of the lower cesoiohagus and proventriculus. From the level oesophagus. of the base of the heart to the point of admission to the gizzard the mass of food in the oesophagus and proventriculus formed a uniform sausage- shaped mass, which seems to have caused death by pressure upon the heart within the thorax. Why this collection of food should have failed to find its way into the gizzard it is impossible to say. Mechanical obstruction there was none, either by unusual food or by stricture. These were at once looked for without success. Some spasmodic stricture of the entrant sjDhincter muscle of the gizzard may have accounted for this, though there was no direct evidence of it. The gizzard and its contents were perfectly normal, and there was apparently free passage both in and out of it. The crop contents were unusually moist with water and watery mucus. They consisted only of green Calluna heather-tops, but there was a much smaller quantity in the crop than in the proventriculus. There was no appearance of damage by shot or other means, such as might account for paralysis of the lower oesophagus, though this would, perhaps, be a plausible explanation, as the damage done to a nerve in the neck by a stray pellet could have been healed without leaving any noticeable scar, and yet the nerve remain severed, thus putting out of action the parts it supplied. No. 1311, a hen Grouse of IQ\ ounces found dead on March 30th, 1908, in Perthshire, was a case presenting almost exactly the same appearances as the above, and with no clearer evidence of its cause. This bird was very thin, and was found not far from a dead grey-hen ; but the grey-hen showed no sign of similar trouble. In this Grouse the crop contained a small amount of large pieces of woody Calluna heather. The proventriculus was perhaps a little swollen, but the lower half of the a3Sophagus was intensely engorged with food, making again a sausage-shaped swelling within the thorax, which must have exerted a fatal pressure upon the heart and blood-vessels. The bird was not suffering from Strongylosis to any noticeable extent, that is, the caecal villi were not engorged. It is a possible solution that the crop having received something irritat- ing in the food, acted suddenly and completely, emptying itself into the PHYSIOLOGY AND ANATOMY OF RED GROUSE 113 oesophagus, and thus paralysing this part of the alimentary tract by over-distension. The contents were not examined for irritant poison, but the birds might possibly obtain some such poison if they fed off heather which had been contaminated by sheep dip in dry weather. This, however, is not probable in March. In the duodenum it is comparatively common to find the mucosa intensely engorged, showing a bright red surface to the naked eye, sometimes all over, and at other times in patches. This is apparently the result some- ^ '- L X J tngorge- times of the presence of Hymenolepis microps, in large numbers ; ment in sometimes of the presence of Trichosoma longicolle. Such a mucosa, seen under the lower powers of the microscope, shows that the vessels of the villi are all full of blood as shown in the accompanying figures (see PL XXVIII., Fio;s. 4 and 4 ia)); but although in many cases the mucosa is ^ ' '^ \ I ' ' o ^ J Cause may thus reddened and Hymenolepis and Trichosoma are abundant, it is be thread- ^ -'■ . worms or also quite as frequently found that the worms are present without tape- worms, any reddening, and in some cases reddenmg is present without any sign of a worm. Nevertheless one very common association in the duodenum, whether it has anything to do with cause and efi'ect or not, is that in one and the same bird Hymenolepis occurs in very large numbers, the villi are densely injected, and the fluid bathing the worms has the appearance of being bloody {see Pl.«cx:xviii., Fig. 2). For example, in No. 1200, weighing 21^- ounces, found sick, the duodenum was of a deep red both inside and out, the villi all injected, the mesenteric vessels all engorged, and jH?/wieno/e/MS was present. The bird had, however, or corn- been feeding on corn, and it is possible either that the siliceous *'<=<='^'°g' spicules of the oats were the cause of much irritation, or that the general venous engorgement resulted from the Strongylosis which was also present. It is also probable that in many of these cases where there is villous engorgement and redness of the mucosa in the duodenum and smaller intestine, Coccidia have been the cause and have been overlooked, and that or the more obvious threadworms (Trichosoma) have really little or Coccidia. nothing to do with the engorgement. It may exonerate Hym.enolepis and Davainea to some extent, that both may be present in masses without any accompanying congestion, but the occurrence of a large number of Trichosom,a longicolle in the duodenum, associated with an accompanying congestion of the mucosa, and the presence in the gut of dark bloody - looking fluid is too frequent to allow this VOL. I. H 114 THE GROUSE IN HEALTH AND IN DISEASE nematode to escape blameless iu the company of the two above - mentioned cestodes. Trichosoma is probably a harmful worm, but as it seldom occurs, as compared with the frequency of Trichostrongylus in the cpecum, the damage done by it is comparatively trilling. In the duodenum then it is possible to have Hymenolepis present in large numbers with or without engorgement of the villi, but when, as in No. 1525, Hymenolepis occupies no less than 8 inches of intestine, extending from the duodenum for several inches into the small intestine, the villi may be exces- sively congested. In such a case, moreover, as in No. 1864, if the bird has Strongylosis the congestion of the mesenteric vessels seems to affect the appearance of the duodenum also. Normally the duodenum and wmgestLn ^^^ paucrcas are pale creamy pink or white with no visible external in appear- blood-vessels : but this is altered under conditions producing con- auce ot ' 1 o ciuode- gestion, to a deep red or bright purple or crimson colour over which the engorged vessels ramify (see PI. xxviii., Fig. 2). As already stated, the villi of the duodenum may be occasionally found in a state of excessive redness, with apparently no trace of a worm of any kind. Such a case was No. 1391, but it was also a very bad case of Strongylosis in a hen found dead, so the change may have been post-mo7'tem only, or it may have formed part of a more general congestion. ♦ Typically the duodenum when badly infested by Hymenolepis looks bulky and translucent, swollen and soft and is of a pinkish yellow colour, with thin walls. The upper end of the ascending limb is often deeply stained by contact with the liver. The contents besides the Hymenolepis are fat globules, no crystals, as a rule, but an abundance of shed, endothelial cells. The fluid con- tents, always small in amount, of the duodenum are generally yellowish, and may be blood-stained if Hymenolepis and Trichosoma are present in excessive numbers. It is not a rare thins; to find that in a sick bird the control of the lower sphincter of the gizzard is lost at the point of death or somewhat earlier, and that the grits have jDassed out of the organ in large quantities into the duodenum. Normally the grits are retained in the gizzard for a considerable time, certainly for months, if they are of any size. Much depends upon the nature of the food, and as already explained the presence of hard, woody seeds may lead to the loss of most of the gizzard grits, in which case they are passed with the dejecta/ ' Viik ]). 97. PLATE XXIX. Rectum Villi of Fig. 5 magnified under 1 inch olij. T3'pical appearance of small Intestine when filled with D. calva. Fig. 6. m\m miy'A ir.^m Rectum Posterior , third ';l;;.'h; very much j ■. inflamed, j M Fig.4. Fig. 5 Kectum, punctifovm infection of villi. Rectum, inflamed condition. Anal ' end. Rectum noniial or nearly so ; the dark staining about the ctecal orifice is due to the proximity of the liver. E . Wilson, Cambridge . Caecum cut open longitudinally Opposite p. 115.] PHYSIOLOGY AND ANATOMY OF RED GROUSE 115 Passing now to a consideration of the small intestine, and its pathological manifestations, the first noticeable point is its external appearance when really full of Davainea calva, as is so frequently the case (see Plate s,,^,,^ j^. XXIX., Fig. 1); the gut is distended, and appears fatty, thin- ^^^^'"''■ skinned, yellow in colour, and rather translucent. Within, there are often great masses of Davainea, but no redness of the mucous membrane. In No. 1219, a cock Grouse of 21 ounces, found dead, the whole of the lower straight portion of the small intestine was enormously distended with food not long eaten. The crop contained Calhma tops, a few obstruo- insects and some seed - heads of a Ranuncidus. The gizzard con- ^^'^^■^° tained plenty of quartz and food ; the duodenum contained Hymeno- '°'^estme. lepis ; and the upper small intestine a few Davainea. The cseca were almost empty, and although no obstruction was visible there was obviously something preventing the admission of food to the cfeca from the lower main gut. The distended intestine measured nearly 2|- inches round, and the thickening of its walls showed that the condition was not merely temporary. The mucous surface was roughened with greyish-white, swollen mucous glands which may have been the cause of the trouble, since they probably failed to supply sufficient moisture to the food for its passage into the cseca. It was a condition analogous to excessive and prolonged constipation, and it is evidently a rare condition in the Grouse, for no other case like it has been seen. A punctiform pigmentation of the serous surface of the small intestine is not uncommon. It occurs in small areas which are thickly dotted with black pigment. Probably it results from a previous inflammatory condition, or small localised peritonitis, which may possibly have tionof been caused by the masses of Davainea within the gut. Grouse No. 1182 and No. 1739 are good examples of this condition. In the latter the pigmentation was more or less generally distributed over the serous covering of the cseca as well as of the small intestine, and as the bird had been wounded by shot some considerable time before it was killed, there is a likelihood of the peritonitis having been more general than local, though there were enough worms and congestion in the intestines to account for the appearance. It is not a common thing to find the small intestine acutely inflamed, or very red or congested, but in Grouse No. 1113 the straight portion was excessively red with orange-coloured mucus, evidently blood-stained, tionof in- and a very large number of Davainea. This, however, was a 116 THE GROUSE IN HEALTH AND IN DISEASE bad case of Helminthiasis, with intussusception ; the caeca also were intensely congested and very much thickened, the lower third especially was blood - red, and full of Trichostrongylus. The duodenum also was much inflamed, and for a male the weight, 15f ounces, was, of course, exceedingly small, showing that it had suffered severely in its struggle with so many parasitic worms. Of this condition, therefore, one might expect well-marked post-mortem evidence. The intussusception was probably the result of great irritation. The only pathological appearance which is commonly seen in the rectum of the Grouse is a reddening along the glandular ridges, due to villous engorge- ment. This appearance is illustrated on PL xxix. where Fig. 2 luSanima- . . . tionof shows the rectum in a normal healthy condition. Fig. 3 shows the rectum. i • n i i ■ i i i-i- i same when miiamed throughout its length, rig. 4 shows the rectum with the posterior third very much inflamed. Fig. 5 represents the punctiform injection of the villi, while Fig. 6 shows the same injection when magnified under a 1-inch objective. The cause of this villous engorgement is obscure, but it is much more frequently found about the lower third of this portion of the gut than about the upper two-thirds, though it may be general throughout the rectum. It does not appear to be dependent upon disease or sickness, though apparently sometimes it has some relation with an excessive number of tape- worms in the main gut. In the c^ca of the Grouse lies the whole origin and cause of " Grouse Disease" in the adult bird. In these blind guts lives Trichostrongylus Caecum. ... , pergraciiis, and these, when present in enormous numbers, produce an excessive amount of irritation and congestion of the vessels and of the Trichn- capillaries in the villi, desquamation of the endothelium, and so much strwigyius. disturbance of the proper functions of this portion of the gut that the contents, consisting of food, mucus, nematode worms, and nematode ova in a pasty and decomposing mess, not only become useless as food, but a grave danger to the bird owing to the amount of toxins produced and absorbed into the circulation. The internal appearance of the normal cjecal mucosa is shown on PL XXX., Fig. 1, which represents a section of the caecum of a healthy bird ; the nodules and granular ridges are yellowish, and the interstices are dark reddish brown. The external appearance of the normal healthy caecum as it lies in the body of the Grouse is seen in PL xxvii., Fig. 1 (i). But when badly PLATE XXX Fiq 4 Fig.3. Fig 5 Opj'osilc p. IIT.] PHYSIOLOGY AND ANATOMY OF RED C4R0USE 117 infested with Trichostrongylus both the external and the internal appearance become quite altered (see PI. xxx., Figs. 2, 3, 4, and Figs. 5, 6, 7, 8, 9). In this Plate, Fig. 2 shows the cpecum much swollen with the mucosa thickened and congested, and the mesenteric vessels engorged, the mucosa show a little red, punctiform inflammation from the injected villi, otherwise the colour is grey and the ridges are tumid and much swollen. Figs. 3 and 4 show the caeca much congested, and the mesenteric vessels engorged with dark venous blood. Fig. 5 represents an exceptional appearance, the four greater and four lesser ridges are well defined, there is no trace of nodules, but there is slight inflammation. Fig. 6 shows the interior of the lower end of the caecum, and Fig. 7 shows a section of the middle third, in both these examples the mucous membrane is much congested, and hypertrophied with fully injected red villi. Figs. 8 and 9 show the appearances in a bad case of Strongylosis. Other extreme cases of Strongylosis are shown on PI. xxxi., where Fig. 1 represents a portion of the caecum at the junction of the lower and middle thirds. Fig. 2 shows a similar appearance in the middle third. Fig. 3 illustrates a section of the first third inten.?ely congested, while Fig. 4 shows the same when magnified under a 1-inch objective. In Fig. 5, showing a section between the lower and middle third, there are large spaces with no trace of ridges ; but it is probable that this is the eff"ect of post-mortem change. Instead of an intestine of a brownish or greenish grey colour moderately filled with soft brown pasty material, and showing greyish yellow lines running down its length on the outside, indicating the eight or nine long villous Appear- ridges within, we see in the caecum of a diseased bird a distended tube, unheauw with overfull and congested blood-vessels ramifying over it on the '^*'^*- outside, standing out very often in conspicuous contrast with a yellowish fatty- looking gut-wall ; or the whole substance of the wall of the caecum may be congested to a deeper tone, and may look dark, blue - black, and unhealthy. Before opening the gut, however, the congestion of the mesenteric vessels is the most conspicuous point. This is due to a venous congestion, and it means that the liver and other abdominal viscera and the right side of the Liver and heart are overfull. The liver may be very dark. It decomposes ^^^''*- rapidly, becoming of a black, tarry, soft and very rotten consistency ; but this is not a safe indication of disease. The diff'erence in appearance between a healthy liver during decomposition and a diseased liver is so uncertain that, after a day or two of summer heat, it becomes impossible to judge whether 118 THE GROUSE IN HEALTH AND IN DISEASE the bird was diseased or not. The right side of the heart is often enormously distended with black blood in a bird that has died of disease. This condition of the heart, however, must not be taken as necessarily present when the ceecum is diseased. When the caeca of a large number of Grouse, all more or less suffering from Strongylosis, are opened up and examined in various stages of freshness, and in some cases after a lapse of many days since death took place, the appearances are very variable. In some birds the upper portions of the ctecum are almost transparent {see PI. XXXI., Fig. 6), but this transparency is certainly increased by the post- mortem maceration of the mucosa. The longitudinal ridges, moreover, gradually diminish in breadth and in villosity as the blind end is approached. The thickenings so conspicuous in some birds are far more abundant at and towards the open end. The ridges are sometimes very obviously alternately large and small, giving four broad and thick and four narrow and thin (.sec PI. xxx., Fig. 5). In bad cases the villi are intensely congested, and in a certain number of cases there is evidence of haemorrhage having taken place here and there. But extensive haemorrhage does not occur in Strongylosis, or at any rate no indication of extensive htemoi-rhage has been seen in any bird dissected. The reasons which lead to the belief that there is always a loss of blood as a chronic symptom in this disease are that the congestion is always present, and is often excessive ; that small haemorrhages have been seen, and that in some advanced cases there is every appearance that one would expect to find in anremia in a bird. It must be allowed that without Dr Fantham's blood examinations this would be an insufficient explanation. In some birds the pale, l)loodless, fatty and degenerated aspect of the tissues of the internal organs was most suggestive of anaemia, and of chronic toxtemia. It is possible to find quite a number of very healthy looking birds with good weights and yet with a large number of Trichostrotujylus and a considerable Ti-icko. amount of villous reddening. This goes without saying in such a hi'h'eaUhv disease as Strongylosis, which is essentially a progressive ailment, birds. Everything depends upon the strength of the bird, and its power of resistance. There is no doubt that some birds will retain their weight and continue for some time in apparently perfect health, with a very great number of Trichostrongylus in the cieca, and a considerable amount of con- PLATE XXXI. Fig I F,g2 F:q 7 iHv ill % Fig 8 Fig 3 Fig 10 Fig 4 1 TRANSPAPffN 1-1 I Fig 6 "■•^T'EBTINE Fig 5 Fig 9 £ Wiisan, Cambridqe Opposite p. 118.] PHYSIOLOGY AND ANATOMY OF RED GROUSE 119 gestion. There is also little doubt that an observer may be easily misled by a physiological redness of the csecal villi due to normal processes of digestion. This is especially the case if the bird examined happens to have been in the middle of this process at the moment of death, and if death occurs without loss of blood. The abdominal viscera must all be more full of blood at that time than at others, though in a bird like the Grouse which eats all day long, the difierence may be less marked than it would be in ourselves or in birds of prey which feed at longer intervals. The chief signs of a bad case of Strongylosis so far as the ctecum |[f°^ °!. is concerned are : — '°^'®- (1.) An excessive number of the worms, which can be seen stringing across between the mucosa and the caked contents of the gut, if the contents are fairly dry. If not, then, by taking a small quantity of the pultaceous contents and squeezing this flat between two glass sides, the worms can be easily seen as transparent threads when held up to the light. Innumerable ova will also be found lying free in the cfecal contents. (2.) The longitudinal ridges, eight to nine in number, are very much thickened, chiefly because the amount of blood held by them is excessive, and the villi are all engorged. (3.) The swellings shown in PI. xxx. (Fig. 1), and conspicuous in a healthy bird as greyish nodules, are far more conspicuous in a case of Strongylosis when they are reddened and congested, and seem to sutler to a greater extent and earlier than the remainder of the ridges and the rest of the CEecum (see Plate xxx., Figs. 6 and 7). In some cases, however, the time comes when every villus in the whole gut seems to be intensely red and congested from one end to the other {see Figs. 8 and 9). (4.) There may be a very great deal of mucous thickening, from the swelling up of the villi and their columnar epithelium cells, and after maceration post- mortem, the ca3cal mucosa seen in water may have the appearance of a furry rug. The mucous contents of such cseca are sometimes obviously- blood-stained, and there is probably a hsemorrhagic form of the disease which results from the sudden access to the gut of a very great number of larval worms all in a fully metamorphosed state. Such a case was produced experimentally at Frimley, and hasmorrhages occurred in the cajca. There is no apparent reason why under certain easily imagined circumstances the same thing might not happen in early springtime under natural conditions. 120 THE GROUSE IN HEALTH AND IN DISEASE (5.) There may be appearances of recovery. In a good many birds the caecal mucosa is dotted all over with minute black pigment granules, in other words some of the villi show no blood-vessels injected, but are filled with pio-ment granules instead. These are sometimes so abundant as to colour the gut. They lie in the villi in great numbers (see Plate xxxr., Figs. 7 and 8). It is possible that they result from previous chronic congestion and that there are circumstances under which the bird may rid itself of an excessive number of Trichostrongylus. If there is any plant Possibility . in of recovery which acts as a vermifuge to this nematode on the Grouse moor, strongy- aud if it could be discovered and encouraged to grow one cannot help thinking that the Grouse might learn to eat it. If this supposed recovery from Strongylosis has not resulted from some unknown vermifuge herb, then it must have resulted from improved conditions of life ; and the one condition of life which is in the hands of the moor pro- prietor is the food supply. It thus becomes imperative to give every Grouse on the moor the best possible chance of overcoming the parasitic pest which produces what is probably the most harmful feature of the disease, namely the chronic congestion of the villi of the cseca. Improve the conditions of life, improve the circulation so that the heart and lungs work more efficiently, and the digestion automatically improves, as also does the elimination of toxins, whether produced by the parasitic worms, or by the food eaten, or by bacteria in the gut. The worms, one must suppose, remain in the gut ; but the congestion is overcome, and the bird is not very much the worse for their presence. But, if the congestion is allowed to continue and become chronic, the digestion and absorption of food must go from bad to worse, and with it every other function of the body. Nothing will prevent the bird in this case from losing its weight, and eventually its life. As for the exact cause of the congestion, it may be due to mechanical constriction of the filamentous processes of the villi by the nematode worms. The iin- Each time the gut acts peristaltically the worms have to hold on caule'of tightly to the mucosa or else be dislodged with the dejecta, and congestion, ^j^g rcsult is sGcu in sections where the villi are evidently mixed up inextricably with the coils of Trichostrongylus. Or it may be due to the chemical irritation of some poison produced in the gut by the worms, or by the defective digestion of food stuffs, or by bacteria living in the gut in its unwhole- some state. Or it may be due to some or all of these conditions together. PHYSIOLOGY AND ANATOMY OF RED GROUSE 121 On the whole the mechanical view seems the most probable. The peristalsis is acting in a way to dislodge the worm, and the Trichostrongylus has no other way of retaining its position in the creca save by coiling round something, and the peristaltic action of the caecum must be fairly strong in comparison with the strength of the worm, for the free end of the worm has to be released at every wave of peristalsis from immersion in a thick, pasty material which is being driven outwards at each contraction of the gut. It thus seems evident that the small and delicate processes of the villi may be continually on the stretch, at first looped round tightly by a worm, the coil may then relax, blood may enter the capillaries, only to be compressed anew and so on, conditions which cannot but produce congestion on a large scale if multiplied a sufficient number of times. So far as the appearance of the caecum in disease (Strongylosis) is con- cerned, the following rough, laboratory notes describe some of the Examples types : — of strongj'. (No. 1908.) Found sick. The caecal mucosa not very red, but whitish, pale, the caeca full of mucus, and innumerable Trichostrongylus. Congestion apparent in the mesenteric vessels but no marked villous engorge- ment, only mucus in excess. (No. 1875.) Trichostrongylus very abundant, but no excessive amount of villous engorgement. Contents of cEeca almost nil, this may account for subsid- ence of engorgement and reduction of redness. (No. 1854.) Caeca very badly engorged at lower open ends, but less towards centre. The whole gut swollen, foul and unwholesome, and To-icho- strongylus very abundant. (No. 1844.) Cjeca much swollen and very full of material. Excessive villous congestion and redness. Abundant Trichostrongylus. A hard con- cretion at the blind end of one caecum shows that matter may remain there sometimes for lengthy periods. The whole venous system intensely con- gested, and the swellings on the caecal ridges exceptionally red with engorged villi. (No. 1842.) Caeca very much swollen, villous redness much marked, and very deep in colour. The whole contents lumpy and irregular, soft and hard, partly dried up, so that from without whitish lumps showed through. (No. 1839.) Cajca very large and unhealthy, thick with whitish mucus. Red 122 THE GROUSE IN HEALTH AND IN DISEASE engorged villi showing up against white fatty-degenerated mucosa and gut walls. Trichostrongylus very abundant. (No. 1728.) Villi red and engorged with blood from one end of the cteca to the other, and the redness especially marked on the swellings along the longitudinal ridges. (No. 1914.) Cfeca swollen with mucus, pale and translucent. Only a few red villi, but very large numbers of Trichostrongi/lus, and innumerable ova. (No. 1215.) Very full of shed mucous cells, or unwholesome, yellow mess, but no active inflammation. Plenty of pigmentation in minute dots. Trichostrongylus very abundant. (No. 1827.) A very unhealthy swollen condition with villi uniformly con- gested and red throughout. Trichostrongylus very abundant. Contents of creca clotted and adherent. No redness except in the caeca, though both cestodes were present in soine numbers. (No. 1747.) Cteca with excessive numbers of Trichostrongylus; very swollen and full of clotted, tenacious, and bloody mucus. The whole gut excessively unwholesome, large and congested with red villi partly macerated, and their cells being shed. Adhesions — probably i^ost-mortem, due to crystalline precipitate in the serous fluid — were to be found all along the csecal mesenteries and peritoneum. (No. 1727.) Cgeca very pale, but with red villi engorged throughout. (No. 1602.) No red villi, but excessively unwholesome contents almost dry and very hard in the centre. Trichostrongylus in excessive numbers ; both cpeca very much distended, pale and swollen with mucus. The mesenteric vessels all congested. (No. 1369.) Ca3ca full of stiffs orange - coloured mucus, beneath which the gut is thin, red, and inflamed in appearance. Many of these ceeca in diseased birds are very thin and red in the middle and upper ends, while the lower open ends contain innumerable red villi. Often it appeared as if not only cells but villi and parts of the mucosa have been shed or detached, perhaps because the mechanical strangulating movements of the Trichostrongylus leave little but the basement-membrane and the wall of the gut, which are there almost transparent. One abnormality occurred in connection with one csecum of No. 1266, namely, an intussusception of the free blind end which has a free mesentery. It was PHYSIOLOGY AND ANATOMY OF RED GEOUSE 123 involved in the attached portion of the csecum until only a portion of the blind end remained visible, and this was black and gangrenous, or nearly so. There was very little sign of Strongylosis. The bird was shot, and was in good condition. With regard to other organs of the body of the Grouse there is more to be said of the lungs than of any other. On this subject the reader , . Pathology may be referred to chapter xii., where Dr Cobbett and Dr Graham ofthe Smith have described in detail the appearance of really fresh lungs, exposed in birds just dead, and their appearance after being more or less stained by i^ost-mortem fluids and decomposing blood. The figures which were prepared with the view of illustrating this difference could not be reproduced in the Report owing to lack of funds. The first series of figures represented the lungs of fourteen Grouse removed at various periods of time after death, and showing marked staining of the tissues. The second series represented the lungs of eight pigeons removed also at various periods after death, and showed the same or very similar ances in staining in all cases where the lungs were allowed to soak in blood- post-mortem stained, post-mortem fiuids, as is the case in the majority oi Grouse which have been shot or bruised, or even carried for many hours over a rough moor in a keeper's pocket or net bag. Even without preliminary bruising or damage there will be found a certain amount of soaking and discoloration of the lung tissues after death. In very bad cases of Strongylosis, such, for example, as No. 1228, the lungs even on the third day after death may be perfectly normal in appearance, and with- out any marked 2^ost-mortem staining. The lungs of birds may, of course, have received some damage, either by shot pellets or by broken bone splinters, and may have recovered with cicatrices, or with part of the lung solidified by organisation of the blood clot into fibrous tissue. Or blood may have been inhaled by the trachea, and so have blocked part of the lung, ^^roducing collapse and solidification. It is wise, in every case when a bird is found dead, to examine the mouth and see whether there has been any bleeding from the lungs. It is unnecessary here to repeat the discussion upon the question of " Grouse Disease" and pneumonia. For this reference must be made to chapter ix., where reasons are given in full for the belief that Klein's explanation ..Grouse of "Grouse Disease" as an acute infectious pneumonia is not the an^^pMu- correct one. moma. 124 THE GROUSE IN HEALTH AND IN DISEASE The normal colour of quite fresh healthy lung is a very clear pink, almost a whitish pink until the organ is cut into when it is found to exude bright red Lung quite blood, and the cut surface therefore immediately becomes bright red. diseased'" "^^^ appearance of fresh lung in bad cases of Strongylosis does not, birds. according to our experience during the past six years, vary at all from the appearance of the lung in health, and there is no sign of solidification or of the earlier stages of pneumonia, congestion, or infiltration in the lung as a symptom of the disease. Pneumonia proper must be an exceedingly rare disease in the Grouse, and probably ninety-nine out of every hundred diagnoses of it are the result of a failure to realise that post-mortem staining and infiltration give an appear- ance which may be mistaken for pneumonia. But it is exceedingly difficult to find even a very small piece of this so-called pneumonic lung which will not float in water, and this is a fairly reliable rough - and - ready test for consolidation. In Grouse No. 1260 small caseous masses were found in several portions of the lung, and also adhesions to adjacent parts, but it was found on examination that two ribs had been broken on each side and had reunited, showing that a pellet or two of shot must have been the cause of the damage to the lung, which (apart from the remains of a small localised abscess here and there) was of a typically healthy colour and appearance. The condition of some very much enlarged veins ramifying over the surface of the proventriculus in this bird, which were probably taking ujdou themselves the duty of vessels previously damaged and obliterated by the accident which broke the ribs, are described elsewhere {see p. 166). In one or two rare cases (Grouse Nos. 899 and 900), as the result of a continued search under high power amongst the debris and fluid procured from Parasites a crushed piece of lung, a living larval nematode has been discovered found 'in*^^ in active movement. This was in a lung which had every appear- "°^' ance of perfect health both in colour and consistence, and yet was taken from a bird so sick of Strongylosis that flight was impossible. A lung such as this, which is a bright, normal, pink colour when the bird quite recently dead is opened (in the case in point the bird died in the hand and was at once examined), may yet in twenty - four hours be so much altered as to have a very deep gelatinous, patchy redness throughout. Later still some parts will turn almost black, while others remain pale ; and the observer who then sees the lung for the first time is almost certain to suspect some PHYSIOLOGY AND ANATOMY OF EED GROUSE 125 pneumonic change in the tissue. As a matter of fact, however, the change is at first superficial, and is more pronounced where the lung is in contact with the liver. The staining gradually makes its w^ay, jJost-mortem, into the body of the lung, so that in a few days a section shows fluid containing degenerating and decomposing corpuscular debris which has leaked into the air spaces and has produced the condition illustrated and described before now as the second stage of pneumonia in Grouse. At this stage the colonies of bacteria block the blood capillaries and form a characteristic feature ; hut this is a iwst-mortem feature. With regard to the liver there is very little to be said. It is an organ which changes perhaps more rapidly post-mortem than any other, both in appearance and in consistence, and yet more has been deduced from its post-mortem ■^ Liver. appearance than from any of the more reliable indications of disease in Grouse. If the liver be examined fresh, even from a bad case of Strongylosis, it will be found to present a normally firm consistence and a healthy red colour. It is true that it may, and probably always will, partake of the general and at times localised abdominal congestion which characterises Strongylosis. But this alters its normal appearance very little ivhen it is fresh, it may be a slightly darker red, and it may be a little more friable, but the change is hardly noticeable. The "black" and "tarry" livers may be ignored, unless they occur in birds that have only quite recently died, as being indications of no value from the diagnostic point of view. The staining even in a fairly fresh liver will often be found upon section to be very superficial and to be creeping towards the centre from the liver surface to the interior. Hence the first portion to show the change right through is always the edge of the anterior lobes. The only examples of disease affecting the liver of birds which have been examined by the Committee were cases of Coccidiosis, and even then the connection with Coccidiosis could not be established with certainty as the specimens referred to were also cases of recovery from wounds or mechanical damage. Small areas of fatty degeneration and localised necrosis have been seen in one or two cases, but have no apparent connection with Strongylosis. The liver in cases of Strongylosis may be considered valueless, from a diagnostic point of view, so far as macroscopic signs go. Microscopically it has been shown to be possibly of more importance (see chapter xii.), and the changes to be found j^ost-mortem are fully described by Professor Klein in his work on " Grouse Disease." 126 THE CxROUSE IN HEALTH AND IN DISEASE The spleen of the Grouse varies ver}^ much in size, and this fact appears to have some connection with Strongylosis. It is comparatively large in young and healthy birds, and is large, as u rule, and of a fresh, red colour Spleen. - _ ° in healthy adult birds ; but in cases of Strongylosis it becomes very small and very dark, an appearance which is noticeable in fresh, dead cases of disease, and even more noticeable as iwst-mortem changes advance. The colour of the kidney in a freshly killed healthy bird is a reddish brown, a o-ood deal paler than the colour of the liver. Normally the lobes of the kidney lie ver}- flat against the dorsal wall of the abdomen, fitting s.Kuejs. .^^^ ^j^^ inequalities of the skeleton. Fig. 9 of PI. xxxi. gives a rouoh sketch of the appearance of a normal healthy kidney as it lies in situ, with the testes overlying the upper lobe, one on each side. The kidneys appear to suffer very little either from the general congestion which must be considered a symptom in Strongylosis or from their function in ridding the bodv of poisons which are probably to be found in disease the general circulation. Only twice has the kidney shown any macroscopic change, and in each case it was due to an enlargement which in Grouse 1292 affected every lobe, but in No. 1107 chiefly the upper lobe. Case No. 1292 was a hen Grouse of 18 ounces found sick, and caught alive on 6th March 1908 in Yorkshire. It was a very thin bird, and in very poor feather ; it had Blaeberry shoots in the crop, no tapeworms in the duodenum or small intestine, but some Strongyles in the casca, which were full of a dark greenish black slimy mess, like that which generally occupies the caeca of Blackgame, the result probably of a low ground diet of soft green leaves of clover, grass, and Tormentilla. The liver was exceedingly dark, but not enlarged and with no spots. The spleen was small (9 mm. long) and black. The kidneys were much swollen, and were brown with black markings, in spots ; l)ut this colouring may have been due to post-mortem change. Case No. 1107 appeared to be the result of acute inflammation, the upper lobe being exceedingly swollen and enlarged, and of a rich red colour (see Plate XXXI., Fig. 10). In this case it will be seen that the testes have been slif^htly displaced from their normal position owing to the swelling of the kidney. PHYSIOLOGY AND ANATOMY OF RED GROUSE 127 Of these two cases, the first had been five days dead, and the other three, in August and 2^ost-')nortem change had set in. The condition cannot be con- sidered in any way directly connected with Strongylosis, or more than two cases would have been found in a series of nearly two thousand examined. The testes appear often to run a normal course of development as the breeding season approaches, however seriously the bird may be diseased. The first sign of any increase in the size of the testes is to be found ^ o ■' , Testes. about the third week of February, at least in the northern half of Scotland. Further south it might be found a little earlier perhaps, but in 1908 for Banffshire the date was February 23rd, while for Durham it was February 24th. In May the testes have increased in size to twenty or thirty times the bulk they had during inactivity, and they are then white and fatty, whereas in winter they are generally small and black and deeply pigmented. Occasionally a very emaciated cock bird will be found with testes only half the normal size during the breeding season ; but, as a rule, the effect of disease on the development of the hen's generative system, both ovar}' and oviduct, is far more noticeable than is the case in the male. If we allow that the prenuptial moult has become post-nuptial in the male as a result of chronic parasitism, it is conceivable that the same saving of energy allows of this sexual development in the male ; whereas in the female, in which the moult is prenuptial as it should be, there are no " savings " to fall back upon in the event of bad disease, and therefore the sexual develop- ment is unsupported, and none takes place. It is very noticeable that in sick Grouse hens there is no development of the ovaries or enlargement of the oviduct and cloaca, such as takes . . Ovaries. place in spring in every healthy hen. The ovaries remain small and undeveloped as in midwinter. Such birds are barren if they pair, for as a rule they cannot lay an egg, but they pair nevertheless, as every gamekeeper knows to his cost in a bad year. Such birds are often very backward in their plumage change as well, suggesting that the time may come when the hens as well as the piumage cocks may have to don the prenuptial dress when the breeding season in^dtseased is finished instead of before it, as is the custom with the hen ^"■'^^• Grouse now (see chapter iii. p. 45). For example, Nos. 1878 and 1879 were two hen Grouse found dead of Strongylosis in May. One had put on the full breeding plumage, but was 128 THE GROUSE IN HEALTH AND IN DISEASE not laying, and the ovaries were very small, dark, and wholly undeveloped. The other not only showed no development of the ovaries, but was still almost entirely in the winter plumage, having had no strength to grow the nuptial one. Such birds are always wretchedly thin, and these weighed 15 ounces and 16 ounces respectively. We found many cases which showed that in the hen the plumage change must come first, for it often happens that {e.g., Nos. 1864 and 1870) the breeding plumage is complete and excellent, even in wasted birds of 13 J- ounces and 14 ounces, whereas their ovaries are as undeveloped as in mid-winter. The suggestion that such weakly hens may achieve a nuptial plumage by a re-arrangement of the pigment in their feathers without undergoing the drain required by new growth, cannot be adopted. This difference between the male and the female Grouse is significant. It seems that, in the male, appearance may be sacrificed to efficiency, between"^ whereas in the female appearance comes first, and the nuptial plumage plumage jg (Jonucd at anv cost, often to the undoing of the hen herself, at changes in -' " ' cock and g^Qy j-^te to the Complete undoing of her power to produce an egg. There must, of course, be many sickly hens that not only don the breeding dress Ijut also lay ;l modicum of eggs. They appear later in the shooting season with every sign of disease and exhaustion upon them, but yet recovering. Grouse that have survived the mortality of April and of May do not die later in the year. They become convalescent through the summer and autumn, owing to good food and better weather. There is no autumnal, mortal Grouse in outljreak of disease ; but there is an increased activity in the collection August are « i . i i i i • t i mi i • i con- of birds that have been sick and are convalescent. Ihese birds can ny, and are shot in August and September ; it is only when they are dis- covered in the bag, in the process of sorting later in the day, that they are suspected of disease, and are forwarded to the Committee for examination. Such birds are not at the point of death, but are, in fact, convalescent. They are not the l)irds that will be killed off necessarily in the coming winter, but may perhaps be still weaklings in the following spring. They are the birds that in the previous spring were badly hit by Strongylosis, but managed to survive April and May, and then were safe with a supply of good and varied food assured to them for at least eisfht months to come.' ^ Vide cliap. iv. p. 72. PHYSIOLOGY AND ANATOMY OF RED GROUSE 12^ As we know much about these wasted autumn hens it is now safe to say that they may be placed in two classes : — History of (1) Those that were too sick in the spring to breed at all, and p-'ning" so remained barren. ®"®' (2) Those that were not too sick to breed, but bred small clutches and reared from two to four or five young Grouse. The first class has the best chance of recovery, for with them there is nothing to occupy their attention but food and rest and their own convalescence. Probably most of these are passably healthy birds in autumn, with no sign of having suffered very badly except in their backwardness as regards change of plumage. These birds usually show a great mixture of plumages, having feathers sometimes of the preceding winter plumage, mingled with an irregularly grown nuptial spring plumage and perhaps some new feathers of the already overdue autumn-winter plumage. The second class is different. They also have a mixture of the same three plumages, but with more complete nuptial feathers, and fewer of the preceding winter plumage. They are the worst of all the sick birds seen in the autumn months. They have been less sick in the spring than the barren birds, but they have been worn out completely by the effort to nest, and by the cares of their family. They have nevertheless won through, thanks to the summer and autumn food supply and summer weather, and by the autumn they are convalescent. By January they will in all probability be once more comparatively strong and healthy, but not so well prepared to meet the critical conditions of early spring as those included in the first class. These, probably, of the second class are the birds that form the first class in the following year, or perhaps they cannot even rise to that, and fall victims to the spring mortality. VOL. I. CHAPTER VI THE WEIGHT OK GROUSE By Edward A. Wilson The weight of Grouse iu counectiou with "Grouse Disease" deserves more O atteation than it has yet received. It is a useful indication of the health of a moor, and in the early days of spring a dead bird found and weighed often affords the best rough guide for making a diagnosis of the probable cause of the trouble. Later, Weight as iii-ici-i indication whcu dead birds are lound m large numbers, the test becomes con- of fllSPISP vincing if indeed any further proof as to the cause of death is required. Even in November and December a very fair indication of the probability of disease in early spring may be obtained by putting a number of birds upon the scales. A really low average weight in these months is undoubtedly a bad sign, and makes the prognosis for the ensuing year unfavourable ; while a good average weight, even if the pigmentation of the plumage is unsatisfactorj^, need give no cause for alarm. Apart from its practical value there are sundry points connected with the study of the weight of Grouse in health and in sickness, which are in themselves interesting ; and many facts in the life-history of the bird are found upon examination to be correlated wath a normal change iu weight from one season to another. It is obvious that before we can usefully investigate changes of weight in sick or dying birds, and can understand their meaning, the seasonal fluctuations of weight in health must be accurately determined and understood. Beginning, therefore, with healthy Grouse, it is found that sex is a primary factor in determining the weight of an individual bii'd. An adult Seasonal <^0Q^ Grouse is as a rule heavier than an adult hen, when both are Uons"'in ^^^^^ grown and in really good condition. This is true all the weiKiii. year round, except in spring, for at this time when the hen begins to sit she is heavier and in better condition than at any other time 130 THE WEIGHT OF C4R0USE 131 Seasonal VARiATfON in Average Weight of Healthy Grouse. (A) HEftLTHY Cock Birds Ounces JAN FEB. MAR. APR. MAY JUNE JULY AUG. SEP. ocr NOV DEC. 25 2f 25 22 21 20 19 18 53 6S7 J/ 3Z \ 13 ^J /T \ X /^ ^ \/ / 19 \ \ ^^ X V J6 V ^ 1/2 (B) Healthy Hen Birds 25 2^ 25 22 21 20 19 Id 3 . 7 10 / / f \ \ ,-■• — --V w \ V eo'h 84 \ \ \ * / / -^^ ^< ' / / ^^~- / 17 (C) Coc/fs Hens 25 2^ 25 22 21 20 19 18 w ^^^ > , |, 'y'z y\ v-^*^ \ —^ A y •^ ^ \^ \ \ ^ X ,,*-'' --• V V /^ r'' F \ \ ""•■"^ -■•^ / y / (EST •*.^ • / ^ ^ / & X B ^m iVofe. — The figures at the apices of the curves represent the number of birds weighed each month. 132 THE GROUSE IN HEALTH AND IN DISEASE of the year, while the cock is not at his best. There is, therefore, at this season, a tendency for the average weight of both sexes to approximate, and even for the advantage to be on the side of the hen. The diiference in the fluctuations of weight between the cock and the hen bird is shown in the Tables A, B, and C, p. 131. The immediate reason for this difi'erence in spring is probably the one which naturally suggests itself; viz., that the exigencies of courtship have a precisely opposite effect upon the male and female. In December, the adult cock Grouse's weight averages 24 •22 ounces, compared to 21 '07 ounces for the hen, while in January it is 23"58 ounces compared to the hen's 21 '52 ounces. These may be considered normal averages, the difference at this time of year being dependent wholly upon a sexual difi'erence of size and build, body and bone. In other words, when the birds are all living under healthy conditions, and when the sexual instincts are in abeyance, the hen being less in all her measurements than the cock has a weight correspondingly less by 2 or 3 ounces. It is, therefore, essential that average weights, to be of use in making a prognosis or a diagnosis of disease, should include the sexes separately ; and also if the weights be taken in August, September, and October that every bird taken for an average be adult. As winter proceeds, we may assume that, unless the weather is unusually open, food becomes less abundant, or, at any rate, less easily obtained and Winter ^^^^ nutritious ; " the sap goes out of the heather," as it is generally feeding. expressed, and there is a large proportion of dry, dark, woody, weather-bitten shoots. Data are elsewhere given to prove that the quantity of such food, both by weight and bulk, found in the crops of full-fed birds in winter, is much in excess of what is usually found in the crops of similar birds in summer. In winter, the crops of Grouse often contain five times as much food-stufi" as they ever contain in summer.^ And, although several factors are at work to produce this difi'erence, one of the most important is the necessity of eating a greater bulk of winter heather in order to arrive at the same total of food value in the end. Calluna heather is eaten almost exclusively throughout the winter ; though Blaeberry stalks and Blaeberry leaf-buds often replace heather, where they ' Vide chap. iv. p. 79. THE WEIGHT OF GROUSE 133 are abundant. Heather seed - heads are eaten in preference to the shoots until, in January, the seeds are shed, and then the birds again fall back on the winter heather shoots. It might be expected that the weight of Grouse would sutler from the shortage of nourishment contained in the winter food : but, as a matter of fact, the average weight of both sexes gradually increases during the winter months until March, the worst and most trying month of the whole year for Grouse. February, March, and April must be considered months of greater or less starvation every year, since the winter food has been picked over, not only by the Grouse themselves, but by cattle, sheep, deer, and hares, and often, too, the whole moor has long been buried deep in snow, or the heather has suffered badly from frost or from the dry parching effect of north-east winds. Sometimes the roots have been frozen in the surface soil, and the soil has been too cold to allow even a drain of sap to rise, so that the Grouse are hard set to find food enough to maintain their weight. Although the hen appears able to remain in good condition, the cock always loses weight to some extent at this time — often far too much — and in consequence suffers from a diminished power of resistance to Entozoa. When thus half-starved, and long before he has any chance of recuperation, the exhausting necessities of courtship force themselves upon him. The cock bird in February is still in full winter plumage, and by March, though he possesses well-developed supraorbital combs, these alone of all his attractions can be considered a special addition to his winter dress for courtship. These crests or combs over the eyes are erectile organs of a brilliant crimson colour, and inconspicuous or even invisible as they are when the bird is at rest, they become in excitement so erect and tense as almost to meet above the top of the head. They are then visible from afar, and are indica- tions of the nervous tension of the breeding season. The bird is at this time bold, noisy, aggressive, jealous, excitable, pugnacious, and magnificent to see. He struts, becks, flies constantly about from one hillock to another, defies all comers, fights viciously, eats little, and constantly attends his mate. Throughout February and March he leads this exhilarated but exhausting and unsettled life, constantly at war, and daily becoming more and more reduced in weight. In addition to all this, he is probably loaded up with parasites, and, though he may live to recover, the strain is often too great, with the result that it is in April and May that the majority of cock birds die of disease. 134 THE GROUSE IN HEALTH AND IN DISEASE With the hen, however, it is very different, for at this time she leads an even quieter life than usual. She feeds constantly, takes no part in the warfare of her mate, and becomes to a greater or less extent "broody." When breeding in this Condition she does not readily take the wing, and puts on flesh and fat. By the time she begins to lay she has a very large store of surplus fat deposited throughout the body and in masses under the skin ; and from this reserve she draws during the three weeks of incubation. For the twenty - three days during which she "sits" she leaves the nest only for a few minutes night and morning, to eat and drink, and her tracks and "docker" droppings are to be found always at the springs or drinking-places, which happen to be nearest to her nest. At the beginning of the nesting season the hen Grouse weighs as much as a heavy cock, sometimes even up to 27 ounces ; but this holds good for a short time only. It is just during these two months of the year, April and May, that she suffers most from " Grouse Disease " ; an inexplicable fact, did we not know that for various reasons, which are given below, March is to be considered the most dangerous month of the whole year for infection with Strongylosis. As the hen sits, her weight, even in health, rapidly diminishes. She is living largely upon her reserve material, and has, in addition to produce from eight to ten eggs. This must be a very considerable drain upon her system, since each egg weighs about an ounce, and each ounce so lost to her is an ounce of her "flesh and blood," the whole amounting sometimes to nearly half her eventual total weight. By the end of June, thanks also to the trials of a family, she reaches an average weight of less tluin 20 ounces, and by the end of July sometimes falls to 19 '5 ounces, whereas the cock, benefiting daily by the improving food and weather, gradually vises from 19 or 20 ounces in March to an average of 24 ounces in August.' It will perhaps throw light on the cause of the marked changes which appear in Tables A and B if an attempt is made to account for them month by month. In Table A, for example, which gives the monthly averages for the healthy male Grouse, there is a very decided fall from 24-2 ounces in February to 21*45 in March, with a gradual rise again from April to August. This sudden drop must be due to courtship, rather than to shortage of food, for though food is scarce at this time the shortage makes no difl'erence ^ Vide p. 145, note. THE WEIGHT OF GEOUSE 135 worth noticing in the case of the hens (see Table B). This argument is borne out by the almost equally sudden rise as soon as the mating is over. The post-nuptial moult in the male takes place in April and May. It is complete in June, therefore any loss of weight in the re^alacing of new feathers would make itself felt in the earlier of these three months. From April to August the food supply is improving daily, and the weight of the cock Grouse gradually increases. And it is by no means easy to see why there should be a sudden drop in September unless it is due to the complete (male) moult to the winter plumage. As there is no corresponding drop in the hen, and, as we know, no similar moult, we are probably right in thus attributing for the September fall in the weight of the male to this autumn moult.^ It is, however, true that although healthy Grouse are at a much lower ebb, as evidenced by their average weight, during certain months of the Relation year than during others. Strongylosis does not necessarily kill them diseaseTnd off" at these seasons. It kills off the hens when they ought to be '^^'gi^t- at their flood tide of health and vitality ; and the cocks when they ought to be on a good rising average tide. We have thus a paradox which may be stated in the following way : — More hens die of Strongylosis during April and May than in any other month of the year, notwithstanding the fact that the healthy hen is then at her best so far as weight, fat, and plumage go. More cocks die of Strongylosis during April and May than in any other month of the year, notwithstanding that the healthy cock is then already recovering the weight which he lost during courtship, and is at a fair average and rising weight. And although one might expect cock birds to die in March and September, when the average weight is at its lowest, this does not occur. And whereas one might expect hen birds to die in June and July, or in November, when the average weight in health is at its lowest, this also does not occur. In attempting to explain this paradox, it is necessary to recapitulate shortly the conditions which lead to an over-infection of the Grouse with the young Irichostrongylns. Elsewhere it has been pointed out that, owing to the small proportion of 1 The cock Grouse normally moults twice a year, first between April and June, and secondly hetween August and November. The normal hen Grouse al.so moults twice a year, first between February and Ai)ril, and secondly during July and August. 136 THE GROUSE IN HEALTH AND IN DISEASE heather which produces good food during the months of February, March, and April, all the birds upon a moor are forced to concentrate upon small areas of feeding ground.' Consequently, there is a tendency for these small nematode areas to become heavily infected with the Tricliostrongylus even from the droppings of healthy birds. At first there are no evil results, for the eggs take some weeks to go through the necessary stages of metamorphosis before the worms become actively dangerous to the health of the bird." Thus, even by the end of February and beginning of March, there is compara- tively little mortality among Grouse.^ As time goes on, however, the infection becomes more and more intensified, for not only do the larval nematodes assume their most active form, but those which have been eaten by the Grouse at the beginning of the period have had time to grow up and produce eggs in the intestine of their host, and these eggs are in turn distributed over the moor to add to the moor infection. The unhealthy conditions do not result in immediate mortality — it has been shown by experiment that birds which have been fatally infected may not die for many weeks.* In some cases a severe infest- ment does not result in death.* Even in March the mortality has not reached its height,* for the majority of birds fatally infected in March will probably not die till April. The infection of the ground continues to increase, and if the same conditions were prolonged for another month or two it is possible that on the majority of moors hardly a bird would survive. Fortun- ately the advent of spring brings a blessed relief to the plague-stricken stock, and with the first appearance of new heather growth at the end of April and beginning of May risk of fresh infection is past. Thus it is that in April the infection reaches its climax, but the birds which die in April are probably the result of infection in March, whereas the birds infected in April die in May, even although the conditions have improved. This is the explanation of the paradox stated on p. 135. It may be assumed that both cocks and hens have the same opportunities for obtaining food, and that the quantity and qualit}' of that food is the p werof same for each, consequently each will be equally liable to infection resistance, j^y ^j^g Strougyle worm. Why then do the cocks die in larger numbers than the hens ? Only one answer is possible, and that is, that whereas at this time the power of resistance of the cock is at its lowest, the power of resist- ' KWe chap. iv. p. 81. - FjWe chap. x. p. 224. ^ KiWc Chart F, p. 142. * Vide, vol. ii. Ajipeudix F. '- Ibid. " Vide Chart F, p. 142. THE AVEIGHT OF GROUSE 137 ance of the hen is at its highest. The fact is sufficiently proved by the com- parison of the weights of the sexes, but if further confirmation be required it would be found in the fact that in June as the cock increases in weight so he becomes less liable to disease, whereas the hen, whose weight is on the downward grade, continues to suffer, and sometimes to die, throughout the summer months. The fact that the average weight of the cock is slightly on the upward grade during the months of greatest mortality is somewhat misleading, unless it be remembered that he is still far below his best condition, and was probably about his worst at the time when he first contracted the infection. The reason why cocks do not die in September, or hens in November, when their respective weights are again at their lowest, is obvious — mere loss of condition is not enough to cause death. It is only where this loss of condition is found in conjunction with a heavy infection of parasites that it becomes a source of serious danger. To return, however, once more to the healthy bird, it is to be remembered that in June the hen undergoes a complete post-nuptial moult, changing from the now faded breeding or nuptial dress, to the autumn or summer plumage, and this she cannot do without an appreciable drain upon her resources. In changing the winter plumage for a nuptial breeding dress in January she differs radically from the cock, who retains his winter plumage until the breeding season is over. The two sexes moult at different seasons, and each twice within the year. The details of the changes have been carefully investigated and described by Mr Ogilvie-Grant, and have been dealt with in another chapter of this Report.^ It has been pointed out that the cock bird begins to grow new feather in March and in August ; whereas the hen bird begins to grow new feather in February and July ; and each of these moults appears to have a Effects of definite effect upon the weight of the bird. There are, therefore, '"°"i*- fluctuations in the weight of the healthy Grouse, which are partly due to the moult, and are therefore seasonal, while others are purely sexual ; it must be noted that the seasonal fluctuations differ as to date in each sex. Both seasonal and sexual changes occur in normal healthy birds. These fluctuations must be fully recognised before any useful deductions can be drawn regarding the changes of weight in birds that are or have been diseased. ' See chap. iii. p. .34. 138 THE GEOUSE IN HEALTH AND IN DISEASE The effect of the various influences which affect the weight of the healthy Grouse are shown in Tables A, B, and C It is unfortunate that some of the monthly averages have been taken from such a limited number of birds. This, in the breeding season, is unavoidable. There is a very natural objection to the wholesale destruction of healthy sitting hens for any purpose. Even dead birds are less likely to be found at this time of year than at any other, for the reason that the majority of gamekeepers dislike the disturbance of their moor which is entailed Ijy a systematic search. It is partly to this feeling amongst keepers that one should attribute the prevalence of the belief that " Grouse Disease" mortality is confined to the spring and autumn with a break between. There is no doubt that the least observed and least understood portion of the life cycle of a Grouse moor is that which lies between May — when the early broods are hatched off — and the end of July, when the dogs are taken out to make a survey of the shooting prospects. Conversely, too, from the intimate knowledge of the moor after August 12th, undue importance has been attached to the idea of autumn disease owing to a certain number of sickly birds being found in the August and September bags — birds which would otherwise have escaped notice altogether, but which were shot in the day's sport, and afterwards picked out as " piners." The point is clearly shown by Charts D, E, D\ E\ p. 139. It is by no means a rare thing to find hens weighing 14 and 15 ounces still Weitrhtas Capable of flight. Often such birds are shot and afterwards picked tion'of"^^ out of the bag as "piners" to be examined, and condemned as cases disease. ^f cliscaSC. The appearances of ill-health are generally abundant. To begin with, the bird is undersized, the bones are found to be unusually small in their measure- ments and slight in their structure, suggesting that the bird was bred late in the previous year. This gives it a bad beginning, and means that the bird, lacking strength, suffered more than the early bred birds during the previous winter months. If the bird is a hen, it will be evident from the naked skin of the abdomen, from the delayed moult of the feathers of the upper parts, and from the almost featherless condition of the legs and feet, that a long and exhausting period of incubation has been endured, followed by a period of incessant watchfulness while the young brood required protection. Often enough a hen "piner" in this condition appears to have suffered from no more definite ride i>. 131. THE WEIGHT OF GROUSE 139 CHARrS SHEWING THE FALLACY OF THE AUTUMN OUTBREAK OF DISEASE. Number JAN. FEB. MAR APR. MAY JUNE JULY AUG. SEP OCI NOV. PEC. 100 90 80 70 60 50 fO 30 20 10 Number of Cocn Birds DEAD A. ^ \ / \ / \ / \ / V / \ -^ A= Q— 90 80 70 60 SO fi> 30 20 10 (E) NUMBSff OF CocH Biros SICIi ONL Y. A / \ /'^ f \ / / \ pA V- 1^^— -■ — G_ 90 ao 70 60 50 W so 20 10 ro') Number of Hen Birds DEAD. .-> /^ V _^ \r v^ n 90 60 70 60 SO 10 SO 20 10 a ■ ■■*- (EM Number of Hen Birds sick ONL Y A /\ f \ y V / \ / V- -^v^ ^^ — ' > — —^ disease than this over-sitting. This in a weakly hen is in itself a sufficient cause of extreme emaciation. Then, again, it may be found that the bird is replete with parasites. These, if the case is a true " piner," will be abundant within and without. The feathers are often alive with Nirmus and Goniodes, the small flat Bird Lice, and the head of the bird is dotted, especially round the eyes and ears, with Ticks of the genus Ixodes. The presence of Oniithomyia, the Grouse fly, depends more upon the weather and season than on the condition of the host. Within, the duodenum will be occupied by a mass of Hymenolepis (tapeworms), or Trichosoma (threadworms), or both ; the main gut by a far more bulky mass of Davainea (tapeworms) ; and the casca may be reddened from end to end by 140 THE GROUSE IN HEALTH AND IN DISEASE villous engorgement due to the irritating presence of thousands of Tricho- strongylus (threadworms). In this state the bird is flushed and shot, and forwarded for a diagnosis. And still one more perplexing item, namely, that scattered here and there amidst a hundred thousand Trichostrongyhis ova, in the contents of the intestine, are encysted spores of Coccidia, showing that the bird may have lost weight in the height of the summer by excessive Coccidiosis, and yet have survived. Our investigations have established that one form of sickness commonly called " Grouse Disease " is due to the excessive infestment of Grouse by Tricliostrongylus, and the most easily recognised symptom of this disease is loss of flesh and weight. It is for this reason that the average weight of birds is the best indication that can be obtained of the prospect of health or disease upon a moor in the near future. The tradition, for it is probably nothing more, that in some outbreaks of " Grouse Disease " birds have been found d3dng or dead well up to weight is discussed elsewhere.' Birds do not die of Strongylosis without exhibiting loss of flesh and weight. Neither do Grouse chicks die of Coccidiosis without losing weight. Beyond these two diseases we have no knowledge of any other disorder which attacks Grouse over considerable areas of country, and kills them in large numbers. The reason for this loss of weight in Strongylosis and Coccidiosis can be seen when a diseased bird is dissected. The i^ost-mortem appearances are fully described in other parts of this Report.^ affecting"^ The following list includes most of the conditions which commonly of Groi^e.* afi'ect the weight of Grouse :— I. In Health. (a) Sex, generally in favour of the male, but in April and May rather to the advantage of the female. (h) Late hatching, producing birds of both sexes unready for the winter ; birds which have missed the best growing months of summer, and which therefore remain permanently undersized and of a poor physique though not actually diseased. ' Vide chap. ix. pp. 204 et seq. ° Vide chap. xii. p. 288 ; chap. xi. pji. 257 et seq. THE WEIGHT OF GROUSE 141 (c) Moult, in the male taking most effect in March and in September ; in the female in July and November ; probably always leads to some loss of weight in either sex. {d) Courtship, in the male always apparently a cause of loss of weight: in the female, owing to increased rest, with some change in the general metabolism and extra opportunities for feeding prior to incubation, seems to lead normally to a very considerable increase of weight. (f) Egg laying and incubation, gradually lead to a loss of weight, which becomes more marked when the hen has had the care of a family of chicks. These cares, notwithstanding the abundance of summer food, often result in producing the lowest possible weights in hens, such loss of weight being in some cases due to an attempt to rear a second brood. During the hen's incubation the cock somewhat recovers his weight, possibly because the food supply is rapidly improving, and because his energies are not so exhausted by courtship. (/) A shortage of good food in a bad winter must often be responsible for a great reduction of weight, and indirectly for an increase of the mortality in both sexes due to Strongylosis in the spring. Similarly the abundance of food in summer, autumn, and early winter must serve to counteract some of the other causes of loss of weight. II. In Disease. {a) Strongylosis in both sexes and at all ages leads to excessive loss of weight, and ultimatel}'^ to death, but the maximum incidence of infection is strictly seasonal, accounting wholly for the fact that both sexes die in April and May in very much greater numbers than in any other mouths of the year. The observation that so many more cocks die than hens has been explained largely by the fact that the average power of resistance of the normal hen Grouse is at its best in April and in May ; while that of the normal cock has just been at its worst. Another factor which bears on this question is shown by refer- ence to Chart F, p. 142, which shows the average monthly weight of cocks and hens found sick but alive and found dead of Strongylosis 142 THE GROUSE IN HEALTH AND IN DISEASE respectively. This table has been prepared to illustrate that birds found sick show the same tendency to lose weight though they do not record such a marked loss as those which have actually succumbed to disease. CHART F Comparison of average weight of Sick Birds and of BIRDS Found Dead; both of Strongylosis. Ounces JAN FEB MAR APR. MAY. JUNE JULY AUG. SEP OCT NOV DEC. «/«/£. SICH BiMS. 21 20 19 18 17 16 15 /4 13 12 -^-- A: .'^-. « *•* - :/ ^3 *'•*''' X 's .^'• * "^' FEMALES. SlCftB/eOS. N^ * *' . \ _, ,-•--. "-^ "rr^^^ ■^ s. ^ \^^ ^ \ 7-'* s. /■ JH^Li^.^lH/i^. lill: . " \ y ^ V. >*'^ ^ FEMALES. FOUND DEAD. V /^ S^ -.^ V -V The curve shows that birds succumb at very different stages of emaciation, in different months of the years. For example, in the case of the cocks a bird will die at 20 ounces in February, at 19 ounces in March, at 18 ounces in April, at 17 ounces in Ma)^, and at IG ounces in June — the conditions of weather and food making life easier month by month as warmth, sunshine, and increasing abundance of food enable the sick l>ird to cling to life a little longer. It is interesting too to note that in the case of the hens, although the average weight in health is 23 to 24 ounces in April and May, it falls in fatal disease to 16 ounces, whereas the cock bird, whose average weight in health is also 23 to 24 ounces for the same two months, succumbs at 17 '5 to 18 ounces. (6) General Helminthiasis, including all disorders due to worms in birds of l)oth sexes and at all ages must also have a share in causing loss of weight : (1) by disturbing the normal digestion and THE WEI(4HT OF GROUSE 143 assimilation ; (2) by the production of toxins in the alimentary canal, many of which are absorbed by the blood ; and (3) by (but this is a minor matter) the worms absorbing, living on and growing on food which in their absence would have served to nourish their host. (c) Coccidiosis, especially in young birds, causes excessive emaciation and frequently death/ It would be interesting, were it possible to collect sufficient figures, to compare local variation in the average weight of healthy males or females with ^ ° ° •' . Local local differences in the height above sea-level, the rainfall, the character variations .of weight. of the subsoil, or the prevalence of disease. For this purpose it would be reasonable to take wide natural divisions such as those which are plotted out for meteorological records, in preference to artificial divisions such as county boundaries and political districts. In attempting this, however, it must be remembered that for a number of years it has been the practice to introduce birds from one part of the country to another, perhaps a hundred miles or more away. This practice makes it difficult to trace true local variations either in size or in other characteristics. It is true that particular districts have been credited with the production of birds distinctly above the average in size and weight. Midlothian, Caithness, and the west coast of Scotland each claim to produce Grouse of a high average weight. To establish this a much more extensive series of weights should be taken than has hitherto been possible. So far as the Committee have been able to ascertain, it is difficult to say with certainty that any one district produces birds of a definitely larger type than any other. The result of the evidence collected is given in the form of a Table on p. 144. ' Vide chap. xi. pp. 252 d seq. [Table. 144 THE GROUSE IN HEALTH AND IN DISEASE Table showing Average Weight of Grouse from Different Districts. County. Date. Cocks. Hens. 5" S . ■ i ^ euTS &- n . "m 1:^ if P m lbs. ozs. 2-5. 41 n ozs. ozs. SCOTLAND- lbs. oza. ozs. ozs. ozs. ozs. 1. Caithness 2. Sutherland, No. 1 Moor Various Aug. 24 14 20 10 23-6 ... ... 12 19 1 25-4 12 16 0 21-3 „ 2 „ „ 24 12 18 0 24 12 15 6 : 20-5 ... >, 24 20 29 8 23-6 20 26 0 1 20-8 ... „ 4 „ „ 30 20 31 0 24-8 20 30 0 1 24 „ 5 „ » 24 12 IS 0 24 12 16 0 21-3 ... „ 6 „ ., 24 20 27 10 22-1 20 24 8 19-6 ») »» ' )> „ 23 12 17 13 23-7 12 15 6 20-5 M 8 „ „ 26 20 30 3 24-1 20 26 2 20-9 ,> 22 12 18 3 24-25 ... 12 16 13 22-4 ., 10 „ ,, 26 12 18 0 24 ... 12 15 0 20 „ 11 „ 12 17 5 23-1 12 15 10 20-8 „ 12 „ Average for County . „ 23 10 14 5 22-9 10 13 7 21-5 174 259 0 23-9 174 230 4 2\ 3. Ross-shire, No. 1 Moor ,, 16 3 4 8 24 2 2 12 , 22 1 „ 2 „ Average for County . 4. Inverness 4rt, Skye .... 5. Moray .... 6. Banffshire . 7. Aberdeen, No. 1 Moor Aug. 24 ,, 16 12 19 0 25-3 12 16 0 21-3 15 23 8 25 14 18 12 ' 21-4 j 98 148 2 24-35 1 23 0 23 ,.. ... 1 ... 4 6 13 23-37 10 15 1 24-1 10 12 14 16 5 20-6 ... 1 ... 12 19 8 26 12 21-7 ji »> ^ )i 12 18 0 24 ... 12 16 0 21-3 J) »i 3 ,, 12 18 9i 24-7 12 15 13j: 21 1 .. .. 4 ,, Average for County . 8. Kincardine . 9. Forfar .... 10. Perthshire . „ 12-14 ,, 14 12 20 2 268 12 16 4 21-6 ... , ... 48 76 34 25 48 64 6i 21-4 32 ... 1 23-231 ... 25 ... 1 19-9 — 12 19 0 25-3 12 16 Ol 21-3 1 17 23-4 28 19 10 20-2 22 19 )» • • „ 16 18 23-5 24 23 9 20 24 16 )» ... „ 19 16 ... 23 26 18 10 20 24 18 )» ... „ 20 4 23 24 21 3 18-6 20 17 ]) ... „ 22 8 24-4 26 23 2 20 21 19 )j ... „ 24 2 23 23 23 8 20-5 24 18 »» ... Average for County . 11. Stirlingshire . ■ > 27 „ 14 8 24-6 27 23 4 22 23 20 73 , 23-5 46 ... 20-2 1 1 8 24 1 )i ... ,, 21 1 i 4 20 ,, 31 12 18 10 24-8 28 23 8 11 0 22 23 21 11 ... Sept. 28 4 6 2 24-5 25 23 4 4 15 19-7 22 18 J) ... Nov. 18 9 12 2 21-5 26 18 10 12 1 19-3 22 17 1) ... Average for County . Dec. 7 7 10 5 •23 5 26 21 8 10 5 20-6 24 18 S3 48 11 23-6 ... 31 39 9 1 20-4 General average weight of full-grown Grouse at commencement of shooting season :— Cocks, 23-97 oi. ; hens, JO-65 oz. THE WEIGHT OF C4R0USE 145 Table showing Average Weight of Gkouse from Different Districts. — continued. County. Date Cocks. Hens. o tc 5| Is w S5 0&: g.2P <^ ozs. 20-5 20-4 21-3 22 21-25 22-5 n 0Z8. 23 23 1^ ozs. SCOTLAND— 12. Argyllshire . 11 ... ,, . . . ,, . . . ,, . . . ,, ... ,, ... Average for County . 12rt. Mull .... 13. Fife . . . . 14. (Dumbarton) 15. Midlothian . 16. Haddington 17. Arran . . . . 18. Ayrshire 19. Lanark 20. Berwickshire 21. Dumfries 22. Roxburgh . 23. Peebles 24. Selkirk 25. Kirkcudbright 26. Wigtown . ENGLAND— 27. Northumberland . 28. Durham 29. Cumberland ,, ... Average for County . 30. Westmorland 31. Yorkshire . ,, ... ,, ... ,, ... Average for County . 32. Derby .... WALES- SB. IRELAND— 34. Donegal Aug. 12 „ 13 „ 15 „ 16 „ 20-24 „ 20-24 „ 14 Aug. 16 „ 12-20 „ 19 Sept. 10 1868, Sept. 17 1873, „ 5 Aug. 12 „ 12 ,, 23 About Aug. 17 Aug. 23 „ 13 „ 13 13 12 5 10 12 12 12 lbs. ozs. is'o ozs. 23-7 24 24-4 24-2 24-5 25-5 24 ozs. 27-5 ozs. 14 11 6 3 12 12 lbs. ozs 76 18 0 24-3 27-5 58 21-3 1 25 0 25 ... 43 12 62 8 23-27 23 12 21 5 7 4 20 12 23-25 14 23-78 5 7 10 24-45 10 24 10 20 1 1 9 25 12 18 0 24 12 16 0 21-3 8 10 6 20-78 3 4 8 24-33 ^^ — '-^- 30 24-6 26-5 21-2 23-5 1 21 1 24 12 5 18 15 25-25 12 15 12 21 20 8 0 25-6 4 5 0 28-5 28-5 28-5 10 14 5 22-97 10 10 10 20 12 15 8 15 7 14 11 29 8 18 6 24-8 24-7 23-5 23-6 24-5 10 10 10 20 12 14 8 13 4 13 12 1 25 8 16 1 23-2 21-2 22 20-4 21-4 62 93 8 24-2 62 83 1 21-5 16 23 0 24-5 15 20 0 21-3 24 19 20 29 10 23 7 25.50 27 22 20 26 9 21-25 1 25 8 ... General average weight of full-grown Grouse at commencement of shooting season :— Cocks, 23-9V oz. ; hens, 20-G5 oz. VOL. I. K 146 THE GROUSE IN HEALTH AND IN DISEASE The heaviest cock Grouse which came before the notice of the Committee was one of exactly 30 ounces from Peebles. Macdonald, in " Grouse Disease," '■ says : " The Grouse in Scotland is a larger and finer bird than that met with in England," a remark which the above figures do not altogether uphold. Macpherson, in Fur and Feather Series, says : " The cock birds not infre- quently weigh 28 or 28^ ounces in the north of England, when in first-rate condition in every respect. Anything over 30 ounces is noteworthy, but a weight of 32 ounces is not unprecedented." " In Yarrell's "British Birds," ^ Red Grouse are said to be at their best, both as regards weight and plumage, in November ; but this is only partly true. Their best months are February, August, and December; and one may say they are at a fair level of condition in those months. ^ Macdonald, " Grouse Disease," p. 103. 2 Fur aud Feather Series, " Tlie Grouse," p. 64. 2 Yarrell, " Britisli Birds," vol. iii. p. 77 (edited by Howard Saunders). Fourth Edition. London : John Van Voorst, 1882-1884. PARI' II. -THE GROUSE IN DISEASE CHAPTER VII CAUSES OF MORTALITY IN THE KED GROUSE By Lord Lovat and Edward A. Wilson In classifying all diseases it must be remembered that before it can be scientifically named it is necessary to ascertain whether the disease in question has ^"^^^^^^y an individuality which can be specifically described and recognised of disease, by definite characteristics and symptoms. It is an accepted rule of medical science that the primary cause of a disease must be found before any attempt can be reasonably made to discover a cure. Yet this important rule has been almost wholly ignored by Ascertain- ment of the maiority of writers upon "Grouse Disease," with a few notable primary •' •' ^ cause. exceptions, such as Klein, Cobbold, and Farquharson. Hardly a writer on the subject but dwells in vague generalities, hope- lessly mixing up observed facts with unsound theories, and primary with predisposing causes ; for instance, if the chief object of the writer . of the following paragraphs had been to confound an already almost previous " ^ o 1 observers. hopeless confusion, he could hardly have been more successful : " What I still maintain is that the unwholesome food which Grouse have been compelled to eat has occasioned both the worms with which they have been infested and at least one type of the disease." "The disease appeared in all its virulence after the heather had been damaged by hard frost; but the crying evil is undoubtedly the overstocking of the moors with sheep." "Grouse have materially suffered from cold late springs which have blighted the heather." " Granting as I do that this nasty little parasite Strongylus does occasion disease in Grouse, is there anything illogical in attributing the cause of the 147 148 THE GROUSE IN HEALTH AND IN DISEASE worm to the bird being compelled to eat unwholesome food, from its natural food the heather being damaged or destroyed from continued blighting east wind? And thus the blight of the heather is really at least one cause of ' Grouse Disease.'" " Insufficient or unwholesome food is the cause at least of one type of disease amongst Grouse." Or the following : — "'Grouse Disease' is caused mainly by overstocking, over-preservation, and the complete and indiscriminate slaughter of certain species of so-called vermin, notably the Peregrine Falcon ; also by the state of the young and old heather after severe and late frosts which do much more harm now that heather burning is done systematically. Also by greed for big stock. Un- natural and rapid burning of heather and a wholly artificial state of Grouse farming; also interbreeding." In the above quotations, which are perfectly sound so far as they go, we have a very fair summary of possible predisposing causes ; but the immediate cause of " Grouse Disease," whether we consider the disease to be pneumonia, or Strongylosis, or Coccidiosis, or Enteritis, or any other sickness in the world, is not touched. The primary or acting cause of Klein's acute infectious pneumonia was believed to be a sub-species of the Bacillus coli; the primary cause of Cobbold's Strongylosis is the nematode worm Trichostrongylus pergracilis ; the primary cause of Grouse Coccidiosis is Einieria {coccidium) avium, and so on ; not east winds or the absence of the Peregrine Falcon. Until we have discovered the active agent in a disease we cannot say that we know its cause. This is a fundamental rule, and to be satisfied with predisposing causes is to be satisfied with less than half the truth, though that half is, of course, very important if our intention is to proceed further in the attempt to discover a remedy for the disease in question. The consequences of what has appeared to be epidemic disease amongst Grouse have been so disastrous from time to time in the past that All moi- it is not surpi-ising to find a very widespread tendency amongst Grouse" sportsmen and gamekeepers to attribute every death and every case "Grouse ° of sickness on the moor to the so-called "Grouse Disease." Disease. j^ ^^ obvious that Red Grouse, in common with other birds, may be subject to more than one form of disease ; but when a certain form of CAUSES OF MORTALITY IN THE RED GROUSE 149 sickness takes an undisputed pre-eminence above all others for a century, as has been the case, apparently, with the Red Grouse sickness, there is some justification for the use of such an expression as " The Grouse Disease," and some excuse for the view held, by those who cannot go into the minutias of microscopic work or of dissection, to ascribe all mortality on a moor to this one disorder. It has been the object of the "Grouse Disease" Committee to investigate this question, and to find out amongst other things : — ^ . . The objects (1) Whether the sickness described universally as "The Grouse of the Disease " in all the literature of the past century which deals with the subject is, in truth, a single disease with individual character peculiar to it alone? (2) Whether a distinction can be discovered between various recorded outbreaks of the so-called " Grouse Disease " which will justifv the opinion held by many writers that two distinct forms of disease, due to two distinctive causes, are confused under the one term ? (3) In the event of a finding in favour of the belief in two or more distinct ej^idemic diseases, what are their respective causes and efl*ects, and liv what distinctive titles and characteristics should they be known ? (4) In the other event of a finding in favour of the belief that only one epidemic disease exists, is Professor Klein's view right, that the only serious disorder amongst Grouse, to which all past records of disease refer, is the one which has for its cause a Bacillus of the B. coli grouj), and for its chief morbid characteristics the lesions of an acute pneumonia in the lung, and "all the characters of an acute infectious epidemic disease"? Or, (5) is Dr Cobbold's view right, that there is a pseudo-epidemic disorder amongst Grouse, answerable for all the recorded outbreaks of disease, which has for its cause a nematode worm of the genus Trichostrongylus, and for its chief morbid characteristics certain lesions in the caeca due to chronic irritation, leading to extreme emaciation? (6) Is there any other form of "Grouse Disease" which is the cause of extensive mortality, but which has hitherto been overlooked ? These are questions which have to be answered before it can be said that we understand the forms of "Grouse Disease" sufficiently to classify them systematically. With a view to defining the main divisions under which the next five chapters are arranged, it may be well at this Com- ... 1 • c CI 1 • inittee's stage to give in anticipation a briei summary ot the conclusions at investiga- which the Committee has arrived. 150 THE GROUSE IN HEALTH AND IN DISEASE The Committee is of opinion : — (1) That the sickness which has in the past caused " Grouse Disease " among the great majority of adult birds is a single disease with clearly defined characteristics of its own ; (2) and (3) it follows that if the two forms of " Grouse Disease " hitherto described as distinct diseases are, in fact, one and the same disease, there is no longer any need to differentiate between them; (4) that "Grouse Disease" is not due to an acute infectious pneumonia caused by the presence in the lung of Klein's Bacillus; (5) that adult " Grouse Disease " is caused by the presence of Gobbold's TricJiostrongyhis in large numbers in the cseca ; (6) that another form of disease in Grouse exists which has hitherto escaped notice. This disease is caused by the presence of Eimeria [Coccidium) avium in the alimentary tract, and is referred to in the Report by the name of " Coccidiosis." It is improbable that Coccidiosis can have been responsible for any of the outbreaks of so-called " Grouse Disease " in the past, for, so far as the Committee's experience extends, it is only the chicks that succumb to this disease, whereas the records of " Grouse Disease " refer only to mortality among adult birds. The grounds on which the foregoing conclusions are based form the subject uf chapter ix. ; chapter x. is devoted to a description of the Trichostrongyhis pergracilis of Cobbold, the primary cause of " Grouse Disease " proper, and chapter xi. deals with the Coccidium avium and Coccidiosis in relation to young Grouse. We have still to discuss the less important diseases of Grouse, of which quite a considerable list may be given ; though their interest is greater from a purely academic point of view than as a serious menace to the Minor (lis- n i • ^ • i i • i -i i eases of well-bemg 01 a moor: indeed with one or two possible exceptions, there is not much probability that they will ever give cause for much anxiety. The exceptions occur most commonly in consequence of the proximity of Grouse moors in certain districts to low-ground shootings heavily stocked with Pheasants and Partridges. It is well known that these latter birds are often the victims of various forms of Enteritis, and cases have been reported to the Committee of Grouse dying of disease apparently contracted from Pheasants which have strayed on to the moor. Amongst other causes of death may be mentioned diseases connected with the reproductive functions, diseases connected with the seasonal moults and diseases caused by deficient or unwholesome diet. But apart altogether from mortality due to disease, a large uuml)er of CAUSES OF MORTALITY IN THE RED GROUSE 151 deaths are directly or indirectly due to accident or to artificial causes. Many of these causes may be traced to the agency of man, and it will be shown elsewhere to how great an extent some of them are avoidable causes of , . 1 1 •! p mortality. by attention to the details oi moor management. Shooting, in all its forms, is responsible for a great deal of unrecorded damage amongst Grouse ; and the examples of " pricked '" birds which have come to the Committee's notice, generally sent as "diseased" birds for examination, show amongst other things how extraordinarily active is the recuperative power of an animal in a state of nature. Bones ire fractured and reunited, even those of the wing, allowing the bird to survive, to be shot again the following year. Peritoneal adhesions may shut off a perforation of the intestine, and even result in a short-circuit of the gut before leakage has caused sufficient general peritonitis to result in death. Chapter viii. deals with the mortality and damage due to accidental causes, or to natural causes other than true " Grouse Disease," and thus clears the way for the proper consideration of the main subject of the investigation, viz., death due to " Grouse Disease." CHAPTER VIII CAUSES OF MORTALITY IN THE RED GROUSE — continued By Edward A. Wilson The causes of death and damage to Grouse not due to " Grouse Disease " may be classified as follows : — A. — Those referable to Artificial Conditions. Accidental consequences of sport, wire-fencing, telegraph-wires, sheep-drains, vermin-traps, poison, etc. B. — Those referable to Artificial Conditions. Extremes of climate ; cold, heat, wet, snow, etc. Destruction by birds and beasts of prey, so-called "vermin," and by the pugnacity of the Capercailzie and Blackgame. Exigencies of reproduction : fighting of cocks, over-sitting of hens, egg- binding, gastro-uterine, gestation, etc. Exhaustion due to moult, and to skin disease affecting the growth of feathers. Deficient diet and starvation, due to frosted, blighted, and over-age heather or to heather-pests; deficiencies of grit and water; excessive or injudicious burning ; and feeding on unwholesome foods, e.g., corn-stooks and sour grain. A. — Causes of Death and Damage resulting from Artificial Conditions. Under this heading there are some causes which may be passed with a mere mention. Death and _ • 1 1 i ■ /• i ■ damage One miglit do SO with all, perhaps, were it not for the interest from arti- i. ^ ^ • ^ ^ ici/-^ ficiai attaching to some of the cases which have come before the Com- mittee, and the light which they throw on the recuperative power 152 CAUSES OF MORTALITY IN THE RED GROUSE 153 of birds in the wild state. Some of these cases occurred in birds which had died naturally ; in others the specimen had been shot, and forwarded for examination as a possible case of disease. The following accidents are within the experience of most game preservers : collision with wire fences and telegrajih wires, accidental damage from vermin traps, snapping by sheep dogs, drowning in sheep-drains or moss-cuttings, etc., and wounding by shot. And of these no one can doubt that the " pricking " of birds due to bad shooting is the most frequent cause of damage. The following examples illustrate a number of these points : — (No. 301.) A hen Grouse whose wing had been cut off clean at the shoulder, presumably by collision with a wire fence, not only survived collision to be shot the following season under suspicion of being a sick ^^^^ ^^"'''• bird, but actually succeeded in rearing a brood of five healthy young Grouse. Another instance of precisely similar nature is recorded elsewhere, in which the bird, a hen Grouse, had successfully raised a brood of healthy chicks notwithstanding the loss of a wing. In the first of these cases the wing was cut off so close to the body that no vestige of a stump was left. The cicatrix in the skin was adherent to the tissues about the rounded end of the broken humerus, of which only the head and neck were left. There was every appearance that the wound had healed well and quickly, probably some four or five weeks before the bird was shot, and soon after the nesting time. In feather and in condition the bird was not appreciably the worse for her mishap. The scapula, which had been broken in two pieces at the time of the accident, had made a strong though irregular union (see Fig. 1). For purposes of comparison a drawing is given of the bones of the undamaged (right) side of the same bird (see Fig. 2). The sternum or breastbone is another bony part also liable to injury, but sometimes without immediately fatal results ; in such cases damage is Fracture of most probably caused by collision with wire fencing. (No. 1672.) A hen Grouse was "picked up alive" on a Berwickshire moor in August. She weighed only 14|- ounces, and was very thin and in very poor feather ; but upon dissection it was found that, perhaps a month or two before, she had broken her breastbone right across by collision with something — probably a wire fence. The smaller posterior portion had been displaced 154 THE GROUSE IN HEALTH AND IN DISEASE forwards and upwards, riding upon the larger portion, and there becoming fixed firmly by osseous union, but with a considerable amount of displacement Prae\ured end oF / left humerus Claviele Fig. 1., No. 301. A permanently fractured left humerus and a fractured and reunited left shoulder hlade. and shortening (see Fig. 6). This accident must have completely disabled the bird for six weeks or a month, rendering her quite unable to fly. Yet Fig. 2, No. 301. The same bone.s uninjured from the right side of the same bird. she had lived, and the broken bone had united. The onl}- apparent disability remaining was the infestment with parasites, Hymeuolcpis, Davainea and 2\ichostrongyliis having all established themselves in excessive numbers in CAUSES OF MORTALITY IN THE RED GROUSE 155 the various portions of the gnt. Thus Strongylosis woukl have eventually killed the bird, but only indirectly and as an after result of the injury, which in itself was cured. (No. 1626.) A young Grouse chick, ll|- ounces, very plump and well feathered, was found dead in Argyllshire, August 1908, and was forwarded for examination. There was no sign of disease, the bird was in excellent condition, and death had resulted from collision, probably with wire fencing, which had broken the breastbone right across. There was hardly any external sign of damage in this case ; but on removing the skin the bruising and bleeding which overlay the more serious damage beneath at once indicated the cause of death. It is easy to distinguish between damage before and after death, when it is remembered that the circulation is active in the former case and in- active in the latter. Any violence done before death is accompanied by bruising and bleeding. Damage done after death may be accompanied by post-mortem staining due to the leakage of bloody serum ; but will never show blood-clots lying under the skin or amongst the muscle - sheets or other organs. (No. 1824.) A hen Grouse, of 20 ounces, was "found dead, but quite warm, about a mile from the nearest part of the moor, and at a place Fracture of down to which Grouse never cro unless when driven off the moor by storm, which very rarely occurs." This was in Cumberland in March 1909. The bird was quite healthy, in good condition, well feathered, and of a fair weight, and having been found dead with feet and legs well feathered, was just the kind of bird to be classed as a case of "the acute form of 'Grouse Disease ' which kills off birds in splendid condition before they have time to waste." But there was some blood in the mouth, and when this clue was followed up by further dissection the root of both lungs was found to have been torn to pieces by splinters of bone from the fracture of two or three vertebras. There was a fair number of Trichostrongylus in the cseca, but no sign of disease and no tapeworms. (No. 1762.) A cock Grouse of 26 ounces was forwarded from Scotland with the correspondence quoted below. The case affords an excellent internal example of the evidence upon which the idea of aii acute and very "^^" rapidly fatal form of " Grouse Disease " has been founded. 156 THE GROUSE IN HEALTH AND IN DISEASE The gamekeeper writes as follows : — " I am herewith sending you a Grouse cock which, I think, must have ' gapes' or something. His neck is very much swollen. This is the third bird of the kind I have seen during the season. We are now seeing diseased Grouse, at least birds having all the appearance of such. In fact, taking all over I never saw worse feathered birds than those we get here. They are especially poorly feathered on the legs." This was written at the end of September when the birds were in full moult. This particular bird had still the old claws on, and two primaries of each wing to shed ; and the feet, though apparently unfeathered, were on closer inspection just beginning an excellent growth of young feathers. One of its eyes was damaged. Attached to the bird was a note saying that it was a diseased Grouse, notwithstanding that it was making a healthy moult for the winter, and weighed 26 ounces. On dissection the swelling of the neck was found to be due to a mass of loose blood-clot ; the thorax also was full of blood-clot, and the bruising and tearing of the blood-vessels about the root of the neck left no doubt that the bird had met with an accident. There were no tapeworms in the bird at all, and no sign of disease of any sort. And though the caeca contained a good many Trichostrongylus, there was no redness, and the mucosa was quite healthy. (No 1841.) A cock Grouse, 18 ounces, found dead on arable land. April 1909, Perthshire. Two or three others had been found there lately, but in this one, which was sent for examination, there was such profuse bruising and so much eifusion of blood about the neck and throat that there was no doubt that the cause of death was accidental. Trichostrongylus, however, was very abundant in the cseca, though there was no redness of the villi ; Davainea was present in large numbers. (No. 1838.) A cock Grouse of 20 ounces was forwarded from Haddingtonshire in April 1909, with two others, definitely showing signs of advanced Strongylosis. This bird, however, had the lungs torn before death by pieces of broken rib, and there was blood in the mouth and trachea. In the absence of any note to the contrary this damage could be accounted for by the bird having been injured by a dog when picked up alive. But, as the bird was found dead in this condition, the damage probably occurred by collision with a fence or some accident of a similar kind. (No. 1397.) A hen Grouse of 26 ounces found dead and in excellent condition, CAUSES OF MORTALITY IN THE RED GROUSE 157 ou May 5tli, 1908, was brought for examination as a case of the acute form of " Grouse Disease," by a keeper whose birds were actually at the time dying in large numbers from Strongylosis. But this bird was found upon dissection to have a rent in the abdomen, and a wound from some wire or fence, which had led to extensive internal bleeding. It was undoubtedly a case of accident, though the bird was fully infested with Trichostrongylus, and there was a considerable amount of villous reddening in the cseca. Had the haemorrhage escaped notice, or had the bird been killed by some less obvious accident, it would have taken its place in the list of evidence which supports the belief in the acute and very viru- lent form of " Grouse Disease" which kills birds before they have time to waste. (No. 1296.) A cock Grouse of 21 ounces was "watched for ten days" in March 1908. During that time he was flushed regularly every day by the gamekeeper at the same place. But during the last few days he wound could not be flushed "without the help of a dog as he was becoming barbed wire, every day the weaker " ; so he was shot, and forwarded as a case of " Grouse Disease." This he was, but only to a very slight extent. The real reason why he objected to being flushed regularly every day was because he had retired to a certain retreat to be away from other birds and remain quiet while a wire-fence wound healed. It was found that the wire had torn through the skin of his breast, and had rent the pectoral muscles, which are the muscles of flight. Had he been left alone he would have recovered in a few weeks, and would have rejoined the healthy birds on the higher ground as soon as he was fit to hold his own. This retirement of a sick or damaged Grouse to a place where he can recruit his health in solitude is in accordance with the habit of almost every animal that lives. (No. 1604.) A cock Grouse of I7f ounces was found dying in Yorkshire in July 1908 with a bad rent in the flesh of the breast, bleeding freely. It was to some extent also sufi'ering from Strongylosis. Two cases of fractured sternum have occurred in Blackgame, forwarded for examination. No. 1234 represents a recent fracture of the sternum in a Blackcock. No. 1232 {see Fig. 3) represents almost exactly the same damage re- united, owing to the fact that the Greyhen, in which it occurred, did not die until some months after the accident. The exact method of overriding and union of the broken bone in this example is shown in Figs. 4 and 5 158 THE GROUSE IN HEALTH AND IN DISEASE which sive a view of the breastbone from each side. Both cases occurred in a Fracture of very curious series of six deaths in Blackgame which were forwarded Biackgarae. for examination as cases of " Grouse Disease," all coming from the same locality. Fig. 3, No. 1232. The breastbone of a Greyhen fractured and reunited. The facts were as follows : — (No. 1.) A Blackcock, October 16th, 1907; weighing 45 ounces; series of was found dying ; in excellent condition. Had been feeding on corn. (No. 2.) A Greyhen, October 26th, 1907 ; found dying, thin, in poor condition, dirty beneath, and much bedraggled ; had evidently been squatting for a long time on the ground, unable to fly. This bird was forwarded by train for examination, and on arrival was still living. She was kept alive, feeding freely on grapes, until November 2nd, when she was killed with chloroform, as there appeared to be some internal damage with a complete absence of any sign of disease. On jjost-mortem examination the breastbone (Fig. 3) was found to have been broken right across near the abdominal end ; but it had since become firmly CAUSES OF MORTALITY IN THE RED GROUSE 159 united again with a little displacement due to overriding of the hinder fragment (see Fig. 6). Clearly this bird was unable to ti.y because the wings from long disuse had become weak, and adhesions about the pectoral muscles probably made the attempt to use them painful. The joints of the legs too were stiif and difficult to straighten, the result of long squatting on the ground amongst wet under- growth. She must have led a sedentary existence for some time, and would probably have died without regaining the power of flight. There can be no Fig. 4, No. 12.32. Yit-w of the I'iglit side of Fig. .3. Fig. 5, No. 1232. View of tlie left side of Fig. .3. doubt that the cause was collision, probably with a wire fence. The organs showed no sign of disease. (No. 3.) A Greyhen, weighing 34 ounces, was found dead in good condition ; had been feeding on corn. Examination showed that an old wound had produced extensive bleeding in the abdomen, but so long previously that the clot was semi-organised and formed a series of concentric blood-cysts. A more recent damage had caused extensive bleeding around the base of heart and into the lungs, and this had killed the bird ; but not until several hours had elapsed since the accident, which almost certainly resulted from collision with a fence. There was no sign of disease. (No. 4.) A Blackcock, weighing 41 ounces, was found dead on November 1st, partly picked by crows or mice, but in fair condition. It had been feeding on 160 THE GEOUSE IN HEALTH AND IN DISEASE hawthorn berries. This bird had a deep wound in the breast, from an accident which had broken the lower end of the sternum. The damage was undoubtedly the result of collision with a fence, or something of the kind. It was exactly comparable to that in the Greyhen, No. 2, but more severe, so that the bird died shortly after the accident. No sign of disease was discovered. (No. 5.) A Blackcock, weighing 39 ounces, was found dead in good condition on November 4th. No food in any part of the gut. This bird had its back broken, and the bone splinters had torn the lungs and the smaller air-passages, so that they gradually filled with blood. The hinder part of the bird's body and its legs must have been paralysed, so that it could not search for food. Fjbroas Union. Fig. 6. Showing method of union of liroken lireastbone. and the drowning of the bird in its own blood took so long to kill it that all the food eaten before the accident was digested, and the remains passed. The whole body was full of venous blood, showing that twelve or twenty-four hours may have elapsed between the accident and the bird's death, which was due again almost certainly to collision with a fence. Once more there was no sign of disease. (No. 6.) A Greyhen, weighing 31 ounces, was found dead on November 4th in good condition ; again the back was broken, but this time lower down at the level of the last rib instead of at the fifth rib as in No. 5. The left lung was compressed and rendered absolutely useless by a large blood-clot which had collected in the thorax owing to internal damage caused by the splintered bone. This bird had evidently lived for some hours after the accident, and had CAUSES OF MORTALITY IN THE RED GROUSE 161 previously been feeding on corn. There was no sign of disease, and every reason to suspect collision with a fence as the cause of the accident. Obviously this series of deaths was not due to an epidemic of disease, though it is difficult to understand why so many birds should have collided with fences in the same locality, where no new wires or other obstructions had been recently erected. The gamekeeper's view at first was that they all had disease, and out- ward appearances to some extent supported him. Later on, however, the Black- game began to leave the valley where they had been feeding on corn, and where the accidents occurred, and once more took to the moors. The keeper reported that the Blackgame on the moors were quite healthy, and continued : " I have been among Blackgame and Grouse for over forty years, and I never saw Black- game affected the same way. If eating green oats is killing them, they have eaten them for over forty years and were not a whit the worse. I have known Blackgame eat oats from September to December, and not a single bird die from it. What puzzles me is why they are not dying in the next valley (3 miles off). When the Blackgame light on the ground they tumble on their heads. If there is a fence hard by they sometimes fly into it. I have seen many birds (recently) showing the same symptoms." All this suggests some form of intoxication, and it is just possible that the sodden and half-rotten grain eaten by the birds might produce sufficient alcohol by fermenting in the warmer process of digestion, to act upon them in this way. There is, of course, also the possibility that grain soaked in spirit had been purposely put down, but in this case it was improbable. It was certain, at any rate, that the epidemic was an epidemic of accidents and not of disease, however suggestive appearances may have been to the contrary. (No. 1627.) A cock Grouse of 21 ounces was caught and killed, July 1908, in Argyllshire. There was very great dilatation of the crop, which was filled with an old blood-clot and with heather, the crop contents had been Damage to there for a long while, and had become dry and mildewed. There were ^Ti^^d two or three cicatrised wounds through the skin and crop ; but these '""'''• were all closed except one, which remained open and suppurating. The passage to the oesophagus downwards was free, and the bird might possibly have recovered in time. The crop was adherent everywhere to the subcutaneous tissues, and so to the skin. And there were numerous enlarged blood-vessels wandering both over the crop wall and also in the adhesions as the result of VOL. I. L 162 THE GROUSE IN HEALTH AND IN DISEASE the diffuse inflammation. It is extraordinary that the bird should so well have maintained its weight — 21 ounces; Davainea was absent, Hymenolepis and Trichostrongyhis were both present, but with no redness in any part of the gut. No. 684 is an example of recovery from a fracture of one of the wing-bones in a cock Grouse. The radius in this case had been broken in two at the junction Fracture of '^^ ^^^ middle and lower thirds, probably from a shot wound. The radius from ^^j.^ must have lived for at least a month or six weeks during the snot c> wound. winter without flying, but made a perfectly sound union notwith- standing, and survived to be shot dead on the wing in April as a healthy bird killed for purposes of crop analysis (see Fig. 7). Fig. 7, No. 684. M Fig. 8, No. 287. Broken and re-united wing-bones. No. 539 is again an instance of the radius being broken in two pieces at about its centre, probably by shot. In this case there was also some evidence of periostitis in the ulna at the same level. The union was in- complete when the bird was killed ; but, though some movement was possible between the broken ends, the formation of callus and new bone had made a considerable advance towards effecting a firm union. No. 287 presented a firmly united fracture of the radius which had been broken in two about the centre. There was no evidence of damage to the ulna. A shortening of 2 mm. (from 50 mm. in the sound bone to 48 mm. in the CAUSES OF MORTALITY IN THE RED GROUSE 163 damaged one), occurred in the united radius, and union was effected irregularly with a large boss of new bone {see Fig. 8). This bird was an undersized hen, killed as a "piner" on August 15th, 1906, and suspected of disease. She was shot on the wing, but was in very poor condition and badly infested by Davainea, Hymenolepis, and Trichostrongylus within, and by innumerable bird-lice and other parasites without. Nos. 434, 984, 1250 {see Figs. 9, 10, 11), all resemble one another in Excessive fhiekening Fibula Impaeled Jhot- Fig. 9, No. 434. Fig. 11, No. 1250. Fig. 10, No. 894. Broken and re-united leg-bones. representing united fractures of the upper third of the tibia and fibula. In each case the fracture was comminuted. The shortening in one leg is from Damage to 83 mm. to 76 mm. The union in each was effected by an irregular |f^g^°t®^ and immovable mass of bony matter thrown out to include the fibula '^o^'Jids. which is also greatly thickened. No. 434 was a cock bird which lived to be shot on January 7th, 1907, weigh- ing 20 ounces. The fractured end of the bone had been rendered smooth by absorption, and the deformity caused by overriding of the lower fragment 164 THE GROUSE IN HEALTH AND IN DISEASE had been partly obliterated. In No. 894 the upper fragment was united to the lower at an angle of 30 degrees. No. 1250 was also a cock, found dead in November 1907, having succumbed to Strongylosis. The shot which caused the •damage can be seen to the left impacted in the bony mass. No. 1304 was a cock Grouse of 18 ounces, caught alive in poor condition, but in fairly good feather. It had evidently met with an accident. There appeared to have been a shot wound in the back, but the chief damage was in the leg, which was dislocated at the tibio-meta tarsal joint, and one central toe Right femur from two ])oint3 of view. Normal left femur. Femur with bony growth. I n c'-ft Fig. 12, No. 696. Fig. 13, No. 696. Fig. 14, No. 696. Fio. 15, No. 998. Broken and re-united thigh bones. was also damaged. These injuries may have been secondary to the shot wound, and may have resulted from a heavy fall ; but the bird had survived, and would have recovered with some deformity. It was, however, a rather advanced case of Strongylosis, and badly infested with tapeworms also, both Davainea and Hymenolepis. Fracture of ^'^^ cascs of damage to the femur may be mentioned : — femur. ^^^ ggg^ ^ united fracture with shortening from 55 mm. to 43 mm. owing to the excessive displacement of the lower portion of bone. The upper fragment forms an angle of 45 degrees with the lower {see Figs. 12, 13). CAUSES OF MORTALITY IN THE RED GROUSE 165 The bird was a hen found dying from Strongylosis in April, but the fracture must have taken place at least six weeks before. From the complete union eflfected the bird must have been healthy at the time, but the accident may have been the starting-point of sickness, which resulted eventually in its death. Fig. 14 shows the undamaged femur of the same bird. No. 998 shows a bony outgrowth of the femur due to periostitis resulting probably from some violence which was insufficient to break the bone (see Fig. 15). No. 1757 was an adult cock Grouse of 16 ounces only, found in Nairnshire in September 1909, sick and unable to fly. It was a bad case of Stron- internal gylosis ; but the original cause of its sickness was a number of lead wounds, pellets which had some time previously passed through the pectoral muscles, the sternum, and the liver. No. 1739 was an adult cock Grouse of 18 ounces, in good feather, but found in Yorkshire on September 5th, 1908, sick and unable to fly. The bird was suffering from Strongylosis ; but there were also healed scars of shot-pellet marks. The lungs were somewhat stained post-mortem, but one of them was thick and solid. It was in part a dark, rich, reddish black all through, and in part normal pink. A line of adhesions joined up the second and third lung-lobes, and there were cicatricial jDuckerings showing where a shot had passed through. The solidification was due to old bleeding. A shot had also recently passed through the neck, traversing the muscles, and tearing a small hole in the trachea, which had remained unhealed. There was bloody fluid in the mouth and trachea. The skin wound, however, had nearly mended, but bits of feather were found in the tissues of the neck, and the scar outside was matted up with broken feathers. The skin wound made by the shot which passed between the ribs and entered the lung had completely healed, and its position only was shown under the skin by a small blood clot which persisted. This bird must have survived its most recent wounds for a week or two at the least. No. 1923 was a cock Grouse of 20 ounces, which was sent for examination from Perthshire in very good condition. The following information was sent with the bird : — " I enclose a Grouse which I picked up to-day. I put up a pack of Grouse. This one rose a little after the others, and after flying about 200 yards dashed to the ground, and when I got up to it it was quite dead and blood flowing from its mouth." Examination outside before opening revealed the fact that the bird had been 166 THE GROUSE IN HEALTH AND IN DISEASE pricked by shot. One of the quill feathers was cut through, evidently by a pellet, and there were marks of shot in other quills. Blood was flowing from the mouth, and an examination of the lungs showed that one of them had been torn by shot so that many of the air-passages were full of blood. But the blood liberated by the original wound had clotted in the lung and saved the bird from immediate death. Had the bird been allowed to rest until this lung and its clot had healed and become firmly cicatrised it would perhaps have recovered. Instead, however, it was flushed and forced to take flight. This broke down the freshly formed clot, and the bird died of secondary hsemorrhage. There was in addition to this a very large clot round the liver, showing that a pellet had entered this organ also. This case is a very good example of what has certainly been described in former years as the sudden death of birds from acute disease, which strikes them down in the pride of health in full flight and excellent condition. It is also a very remarkable case of long survival after serious damage caused by shot wounds. No. 1260 was an adult cock Grouse of 19 ounces, found dead on January 3rd, 1908, in Argyllshire. This bird had been badly sprinkled with shot some time before its death — at least a couple of mouths, judging by appearances. That it should have survived at all is extraordinary. Three shot pellets were found lodged in the tissues of the neck ; two ribs had been broken on each side, and had firmly united again. There were small caseous masses in the lung, the remains of small localised abscesses which had been caused by the passage of the shot. The pleura were fastened to the ribs by traumatic adhesions ; and as the result apparently of some obstruction or damage to the usual set of veins there was a great enlargement of what are generally quite insignificant veins in the wall of the proventriculus. This swelling, however, is purely vascular, and a difl'erent thing altogether to the swelling in the two cases just described. It has in this respect some similarity to the case which follows, a case in which the increased vascularity of the proventriculus also resulted from damage to the thoracic viscera. No. 1279 was a cock Grouse of 23 ounces, found dead on February 17th, 1908, in Inverness-shire. It was in excellent plumage and condition, and although an abundance of Strongyles was to be found in the coeca there was no redness and no ensforffement of the villi. The cause of death was apparently collision in flight, and the chief damage CAUSES OF MORTALITY IN THE RED C4R0USE 167 was that suffered by the heart, Avhich was much enlarged and swollen out to twice its normal size by a great extravasation of blood in the muscular tissue of the walls, both of the auricles and ventricles. The veins running in the wall of the proventriculus were much engorged. The lungs were unhurt, and otherwise the bird was perfectly normal. No. 1899 was a hen Grouse of about 17 ounces, found on July 23rd, 1909, in Sutherlandshire, sick and unable to fly. It was in very poor condition, and heavily worm-infested. But the chief cause of distress was a very large tumour Tumours caused by an aneurismal-like rupture of the vessels in the inner walls of bv"shot the gizzard. The cavity of the gizzard was enormous, and the organ "^""""i- occupied nearly the whole of the abdominal cavity, causing complete compression of most of the intestines intensified by the formation of adhesions due to peritonitis and the stretching of the normal mesenteries over the tumour. The tendinous and tougher portion of the gizzard had retained its normal size and shape, but the fleshy part had become greatly distended. The tough lining membrane was the part which had given way. No. 1177 is probably a case of a dermoid cyst situated in the neck, though the cyst simulates the occasional result of a shot wound in which small fragments of feather are enclosed in a caseous mass in the connective tissue between the skin and the crop. The crop in this case was not damaged. Scraps of feather formed the nucleus of two tumours 35 mm. and 15 mm. in diameter respectively. The sebaceous matter, of a golden yellow colour, was in concentric layers, enclosed in a thick fibrous envelope with innumerable blood-vessels covering the outer surface, and supplying the cyst wall with blood. No. 1159, a hard fibroid tumour 1|- inches (45 mm.) in diameter, pro- truding from the foreneck of this bird. The nucleus again was a fragment of feather, and this occupied a small abscess cavity in the tumour with a sinus leading to the outside of the skin. The tumour was covered by bare, rough, and rather thickened skin, devoid of feathers, and resulted probably from a shot wound. There was no connection with the crop. Various accidents may happen to the foot and metatarsus of the Grouse, ranging from complete loss of the foot at the tibio-metatarsal joint Damage to as in No 437, to the loss of toes at the metatarso-phalangeal joints, ^*^'^^" or at the various inter-phalangeal joints as in No. 970. Steel vermin traps will perhaps account for some of these cases, but in No. 970 the appearance of the stumps of toes on both feet, to a difterent 168 THE GROUSE IN HEALTH AND IN DISEASE extent on each foot, suggests frost-bite as the cause ; or at any rate some form of gangrene rather than steel traps. A likely explanation is the strangulation of toes, sometimes even of feet, in infancy by the tightening of strands of sheep's wool accidentally wound round them. This is a common accident with Lapwings. An instance of the death of Grouse in a vermin trap may be recorded, in which two healthy cocks fighting in the spring accidentally came together into a " Samson " trap, and were simultaneously killed. No. 1606, a cock Grouse of 18|: ounces, was found dead on July 13th, 1908. There was a very little Calluna heather and Blaeberry leaf and stem in the Dama-'eto crop. The bird had probably found difficulty in obtaining sufficient ^'^'' food for the lower bill was split and curved, forming an unhandy instrument for plucking heather. The death by starvation, however, had been hastened by Helminthiasis. Davainea was abundant ; Hymenolepis filled the duodenum, which was purplish red, very congested, with engorged villi within, and engorged venules without ; while the cajca were excessively congested within and without, and Trichostrongylus was present in great numbers. This bird would very probably have recovered during the summer but for the additional handicap of its damaged bill. It had survived the two months of highest mortality, April and May. Many interesting cases have also been recorded of recovery from flesh wounds either by shot, or by barbed wire, and the following have come under the notice of the Inquiry : — No. 1242 represented a long standing leakage of the crop, due to a wound through the skin and crop- wall. Owing to constant use of the crop, and to Damage to ^^® alternate distension and contraction of the overlying skin, the °''°P' adhesions between the edges of the skin and crop-wall had become permanent before there was any chance of the openings in either being closed. Bits of heather pressed constantly between the lips of the wound had prevented healing, and had defeated the efforts made by the crop to pass all the food into the gizzard. The bird had therefore to eat more than the normal amount to make good a chronic wastage, and this accounts for the very abnormal dis- tention of the crop which often characterises cases of the kind. No. 1627 is another case of the same nature. Either or both of these last two cases may have resulted from shot wounds, CAUSES OF MORTALITY IN THE RED GROUSE 169 or from rents made by barbed wire. The latter is probably the cause in the majority of cases. It is fairly common to find shot pellets loose among the contents of the crop or in the gizzard. They have sometimes been lodged there when the bird was killed, but have more commonly been picked up and g^ot fve- swallowed as grit, or out of simple curiosity. In one case a shot pellet found m was actually encysted in the thin wall of the crop. It would have °™P' found its way eventually into the crop without any damage ; but it is at least curious that a pellet having entered the bird with sufficient impetus to get through the skin and half way through the wall of the crop should not have gone right through into the contents. No. 1150 is a similar case resulting from a shot wound ; the pellet had entered the body of the bird, and having perforated two portions of the gut had then lodged in the gizzard. Localised peritonitis had followed, causing abundant adhesions, and a short cut had been established between the gizzard and the main intestine as well as another from the upper portion of the main intestine to a lower portion of the same. The danger to young chicks in sheep drains and in moss cuttings for " peats," or for general surface draining, has already been mentioned. It is greatest during a " spate " after a spell of dry, hot weather in June or July, when young broods have been led by their parents to take shelter sheei? from the sun in dry drains cut with steep sides. The sudden filling of these drains is responsible for the loss of many chicks before they find a place to scramble up into safety. This danger is well recognised, and the best method of avoiding it is dealt with in another chapter.^ Accidental poisoning is a rare cause of death in Grouse. A few cases have been brought before the Committee as cases of " Grouse Disease." It is not easy to guess how poisoning occurs, for poison used in killing vermin Accidental is administered mainly in eggs, and in the carcasses of fur-bearing po'so'^i'^g- animals, neither of which are likely to be tampered with by Grouse. Poisonous sheep dip has been blamed in some cases ; but it is difficult to believe that it can be more than the rarest cause of accident. The theory that many Grouse are poisoned by lead pellets, whether swallowed as such, or in solution as carbonate of lead in drinking water has been ingeniously upheld by an elaborate calculation of the amount of shot scattered over a moor ' Vide chap. ii. p. 15. 170 THE GROUSE IN HEALTH AND IN DISEASE in a shooting season ; but though the crops and gizzards of Grouse do occasionally contain a lead pellet or two, they are sufficiently uncommon to be a matter of curiosity to the finder rather than a cause of sickness to the birds. ^ The following is an account of what was supposed to be accidental poisoning of Grouse by sulphate of Barium. It is given by Macpherson in the " Fauna of Lakeland."^ Quoting John Borrow as writing from Alston in 1837, he says : " In consequence of the Grouse in some parts of this neighbourhood having been unable to procure sand (owing to the depth of snow), they have picked up particles of the sulphate of Barites, which appears to have been the cause of a very great mortality among them. A person whom I can depend on assures me he saw not less than forty brace dead upon the moors a few days since." One may, I think, legitimately wonder whether this mortality was not due rather to a grit-starvation, accompanying and augmenting the evils of food- starvation, which is always present to some extent with deep snow. The Rev. E. A. Woodruffe Peacock gives cathartic flax as a cause of death by violent purging to young Pheasants ; but no case of poisoning in Grouse can be attributed to the consumption of any plants found growing upon a moor. Several cases of abscesses and septic poison of the leg, which resembled Abscesses " bumblefoot " and "whitlow," were sent up for examination during and septic poison. 1908 {see Plate XXXII.). No. 1G81 was a cock Grouse of the year, shot purposely on August 25th, 1908, on account of the condition of its body and feet. The foot of another Damage Grousc was afi"ected in the same way though to a less degree. This and leg. bird Weighed 15^- ounces, and its condition was fair. Both feet were much swollen with collections of caseous pus. The figures shown on Plate XXXII. were drawn from the bird when quite recently dead. It was killed " on an exceptionally dry juniper hill" in Inverness-shire. There were no abnormalities in any other part of the bird, except the usual infestment of Trichostrongylus ; but the organs were all apparently healthy. No. 1744 was an adult cock Grouse shot in September, in Perthshire, weighing 19^ ounces, and somewhat tliin. It exhibited the usual infestment with Hymenolepis, Davainea, and Trichostrongylus, but was otherwise healthy except for a swelling of one of the toe joints, very similar to the case just described (No. 1681), but not symmetrical. ' Vide Macdonald, "Grouse Disease," p. 160. ^ Vide Reverend H. A. Macpherson, " A Vertebrate Fauna of Lakeland," p. 323. Edinburgh : D. Douglas, 1892. PLATE XXXII. O O X' o ,o W D o O 'I- O O UJ _i QQ c o E.Wi]aon,Camb»'idge Ojiposite ]i. 17!).] CAUSES OF MORTALITY IN THE RED GROUSE 171 No. 1675 was a youug bird of the year, shot in September, on the same moor in Inverness-shire which produced No. 1681, and another similar specimen which was not forwarded. All carae from a very dry, healthy, juniper-covered valley, and all had appearances much resembling the disease known to poultry farmers as "bumblefoot." No. 1918 was an old hen Grouse killed in Yorkshire, which weighed only 13f ounces, and was exceedingly thin. This bird had a swollen knee of the same character as the above, and there was some evidence that it was an old standing trouble, for the claws on the foot of the damaged limb were of an abnormal length, whereas those on the foot of the sound leg were broken and worn to stumps by the extra amount of wear and tear. The feathers of the left undamaged leg were similarly much worn, whereas those on the damaged leg were in good condition. The bird was suffering from Strongylosis, the cpeca being very much congested and full of Trichostrongylus, and the villi very red. There was an old blood-clot over the liver, which may have resulted from a stray lead pellet, and the swelling of the knee joint in all probability should be attributed to damage by another pellet which may have struck the bird at the same time. In poultry farming " bumblefoot " is the name given to Bumble- any form of abscess in the foot, and as the abnormal structure of the ^°°*' Dorking's foot with its extra toe made this breed particularly liable to have a suppurating corn or other accident of this nature, it was considered at one time to be almost peculiar to that breed. It is evident, however, that in the Grouse which have been considered above, and in the poultry affected with " bumblefoot," we have generally the result of localised suppuration from septic infection, following upon some small and unnoticed wound or damage such as a scratch or bruise. A " whitlow " is exactly comparable to this affection in the toes, and a whitlow may be a septic affection of the superficial or deeper tissues, and if of the latter, the infection may spread to tendon sheaths, or even into the joints themselves, or upw^ards between the muscles. In the Grouse above mentioned the suppuration is more or less localised, and the pus, having no free exit, has become caseous in the lapse of time, hence the firmness of the swellings. 172 THE GROUSE IN HEALTH AND IN DISEASE B. — Causes of Death and Damage restdting from Natural Conditions. Nearly all tlie causes of death and damage due to purely natural conditions have from time to time been so well described that it will here suffice merely to recapitulate them.^ 1. Climatic extremes are well known and well recognised. They may Climatic occur from the time the eggs are laid to the end of the bird's life, extremes. ^^ every age, in every season, and every year, the welfare of the bird is threatened by excess in one direction or another. Excessive heat and its usual accompaniment, water famine, are both somewhat Heat and Uncommon at the time of year when they would be most dangerous drought. ^Q Grouse life. They are referred to in chapter ii.^ The following abstracts sum up the harm done by wet and cold. Macdonald in "Grouse Disease" has no doubt about the matter when he writes that Wet and " Damp and cold never fail to produce diarrhcea, cramp, and disease " ; '^°^^' and again, " Excessively cold or wet seasons are succeeded by great mortality among birds, and Grouse suffer more in wet than in dry seasons, how- ever cold — this was strikingly demonstrated in the wet season of 1872-1873"; and again, "Cold wet causes bad hatching seasons."' So also Macpherson in the Fur and Feather Series says that young Grouse " do best in fairly dry seasons." * And for the bad effect of cold and wet on the food supply Macdonald, again, in "Grouse Disease," says: "We can also connect the disease with wet seasons. The heather does not quite ripen, particularly the small tops on which Grouse chiefly feed."' There seems, in fact, to be a consensus of opinion amongst those who have had the best opportunities for judging, that the hatching season can hardly be too dry so long as there are dewy nights. The chicks can supply their needs by drinking dew in the morning, and beyond this they find sufficient moisture in the insects and young succulent moss-cap.sules and heather shoots which form their staple diet, and which contain something like 60 to 80 per cent, of water. The sitting hens want water and must have it, and their bulky dropjiings may * In connection with the effect of weather conditions upon Grouse, much additional evidence has been collected by the Coniniittce, and is summarised in Appendix G., vol. ii. In view of the information now made available for the first time, it may become necessary to reconsider some of the opinions of recognised authorities referred to in this chapter. ^ Vule chap. ii. p. 16. ^ Macdonald, " Grouse Disease," pp. 24, 40. ■* Fur ajid Feather Series, " The (irouse," p. 24. ' Macdonahi, " Grouse Disease," p. 40. CAUSES OF MORTALITY IN THE RED GROUSE 173 always be found on the edges of the burns and springs nearest to their nests. They are reported to suffer seriously in a drought. But when all is said, excessive heat and drought are far less to be feared in the British Isles than excessive wet and cold. Sunstroke, "staggers," and " splanders " in wild birds of any kind are extremely rare when compared with the results of an exces- sively wet hatching season, especially if it happens to be accompanied by cold. Too much wet is undoubtedly more harmful both to the sitting hens, to the eggs, and to the young birds when hatched, and for a month at least after hatching, than any other climatic extreme to which Grouse are subject. o' J •) Excessive Excessive rainfall is said to account for the scarcity of Grouse on wet a great danger. the moors of the west of Scotland and of the Western Isles, and to this John Colquhoun adds that " Grouse are never so plentiful on the west coast, from the wet springs addling so many of the eggs." And again, " Protect as strictly as possible, and kill every rapacious bird and beast on the ground, there never could be half as many Grouse reared in the west as in the north or centre Highlands ; and the reason is the humid climate prevents it." ' " Every sportsman knows that the Grouse in the north or centre Highlands of Scotland are immensely more numerous than in the watery west." * The nesting season of 1906 was most typically a bad wet season everywhere, and in walking over some of the Scottish moors, south of Perth at any rate, nest after nest was found to be deserted with a full clutch of eggs in which the chicks had died just before the time of hatching. Second broods are in such cases no doubt produced, but if an early winter sets in, or if the autumn turns wet and cold, these late-hatched broods swell the ranks of the poorly- Secoud feathered, undersized birds which appear in spring as " piners," and broods and are liable to succumb eventually to disease of one sort or another. The question of the diminished value of second broods is fully discussed in another part of this Report.^ In every way, except in checking the growth of the heather, hard frosts and heavy snow do less harm than excessive rains. A certain number of E^ect of hens may be occasionally frozen to death upon their nests, as has been o'^^foo^^"' recorded by Stuart- Wortley (Fur and Feather Series). Eggs, too, ^"PP'y- may be " frosted " when late frosts are sufficiently severe,* or young Grouse 1 Colquhoun, " Moor and Loch," vol. i. pp. 194-198. ^ Ji,i±^ p. 198. 3 Chap. xsi. pp. 469 et seq. * W. A. Adams, " Twenty-six years' Reminiscences of Scotch Grouse Moors," p. 94. London : Horace Cox, 1889. 174 THE GROUSE IN HEALTH AND IN DISEASE may be killed by late snowstorms, as in 1864 on Glenshea ; but such occur- rences are very rare. The power of resistance of the egg to frost is dealt with in another chapter/ Still, however little direct harm excessive cold may do to Grouse, the indirect harm is often very great, and there is no doubt that late frosts in the north of England and in the south of Scotland, catching the heather after the sap has begun to rise, often reduce the available supply of food. It may be well to review what has been written from time to time as "Frosted ^^ ^^^ effect that "frosted heather" is supposed to have upon the heather." Grouse. In Macdonald's "Grouse Disease" a Scottish forester is quoted as having stated that during a certain epidemic there was no " Grouse Disease" all along the sea coast where the heather does not suffer by frost, while 10 miles or so inland, beyond where the sea exercised its influence, there the " Grouse Disease " began. It is there stated that the dissection of Grouse that had died of the disease proved that their crops contained frost-bitten heather." And, again, in a quotation from Colquhoun's paper, it is stated that in Perthshire, in 1852 and 1853, the heather was excellent, and in consequence there was no disease, while in 1854, 1855, and 1856 the heather was frosted without snow, and there was bad disease. Again in 1857 the heather was excellent, and there was no disease; and so on.^ Speedy, however, says : " Heather which has been killed by frost and entirely divested of its nutritive qualities is about the most unlikely thing for Grouse to feed upon."^ He says, too, '^that after bad disease there are more survivors on the high exposed heather-frosted parts of the moor than on the lower sheltered localities, and that "'Grouse Disease' has not been peculiar to those seasons when the heather was most generally frost-bitten, or when it had not been covered and protected by snow. . . . Some of the most fatal visitations have been preceded by winters more remarkable for mildness than severity." The statements contained in the above quotations from Macdonald and Colquhouu are proliably due to a misuse of the term " frosted heather," for there is a condition of heather which is not rightly called "frosted heather," and it will ' Vide cliap. ii. pp. 10-12, vol. ii. Appendix H. ^ Macdonald, "Orouse Disease," p. 40. •' Ibid., 1) 122. * Tom Speedy, " Sport in the Highlands and Lowlands of Scotland," p. 202. Second Edition. Edinburgh and London : WiUiam Blackwood & Sons, 1886. CAUSES OF MORTALITY IN THE RED GROUSE 175 prevent misunderstauding if the meaning of the term is clearly defined. To begin with, young, fresh, green heather of the early summer may be caught by a late black frost which sweeps over the moor and literally " scorches " it red. This is a comparatively frequent occurrence in the north of England, and was well exemplified on a certain Yorkshire moor in the early summer of 1907. The countryside was green one week, and "as red as a fox" the next. Every leaf that was turned red by the freezing winds (there was no snow in the question) died, and eventually dropped oflP without recovering. But the plant was not killed ; it very soon put out fresh leaves from the lower stalks, and the moor in a few weeks was as green as ever. Still, the fact remains that the birds of that moor were suddenly reduced from a very abundant to a very limited supply of food, for in no case will a Grouse eat such useless stuff, nor has a Grouse's crop ever been found to contain this fox-red frosted heather. It is dead, and the birds know it, and forthwith proceed to look for something that is not dead. They will not eat it, and therefore any harm that accompanies its appearance is due, not to the presence of this useless refuse, but to the sudden reduction of the wholesome food supply. Such fox-red frosted heather must on no account be mistaken for the dark, red-brown, winter heather, which is secure from any ordinarily severe frost, and is merely the resting condition of the healthy living plant. The two are totally distinct in colour, the former being, as has been said, brick-red or fox-red, and the latter a deep brown, or dark, reddish brown, often associated in the leaves of the other side of the twig, with a deep or vivid winter green. Such heather is alive and healthy, and forms perfectly wholesome food for the Grouse ; it is, in fact, their staple winter food, heather" The only point is that being somewhat dry and sapless (in which lies the whole reason of its immunity to frost), and lacking in food-value when compared with fresh, young, summer heather, about three or four times as much has to be eaten by the bird to get the same amount of nourishment. This dark, winter heather cannot be correctly called "frosted," since the change in it is merely due to a seasonal alteration in the chemical condition of the cell contents, while it remains in the healthy resting winter state. With certain modifications it may be stated generally with regard to the two forms of " frosted " heather that in the one case the heather is dead — having been killed by even a moderate frost— and that in the other it is living, and is proof against even a severe frost. The presence or absence of snow on the ground makes a great difference in 176 THE GROUSE IN HEALTH AND IN DISEASE time of frost. Snow acts as an efficient protection to the heather, and only the extra long twigs that protrude beyond the snow are aflFected by protection frost. Hard frost after snow trims the heather by cutting off and iroiu frost. , .,,.,, ■, •/ o killing all the longer pieces, so that the leaves bleach whitish grey, and eventually drop off. This may happen even to straggling pieces of dark brown, winter heather if the frost is severe enough ; but it requires a very low temperature and a prolonged exposure to affect real winter heather to any great extent. There is no other condition of heather which can with any show of reason be called " frosted " ; and it may be urged that no heather should be so named except that which has been nipped and killed beyond all chance of recovery. To call the resting condition of winter heather " frosted " is as unreasonable as to call any evergreen shrub "frosted" because its winter leaves are darker in colour than those which it produces in early summer. Closely simulating the fox - red, frosted heather, however, is the heather Eff t f damaged by a certain beetle known as Lochmcea suturalis. This pest heather has long been recognised in Argyllshire, Ayrshire, and Dumbartonshire, and its ravages were described by Mr Grimshaw in 1898.^ This subject is also dealt with in the present Report.' Before leaving the climatic causes of death and damage to Grouse, something remains to be said about heavy snow. Its most obvious danger lies, of course, Heavy ^"^ Starvation, since a heavy snowfall, unaccompanied by wind, and not snow. followed by a thaw for many weeks, reduces the available food-supply to a minimum, and drives the Grouse to travel far and wide over cultivated lands, into gardens, town outskirts, and even to the seashore for a scanty living. It is recognised that one of the best ways to help Grouse under such circum- stances is to lay bare patches of heather by breaking through any hard crust that may have formed on the surface of the snow. This may be done either by rakes or harrows, and the spots chosen should be those where there is known to be the best supply of good feeding heather. As a rule there is sufficient wind with the snowfall to ensure that large tracts of ground remain uncovered on exposed ridges, and on the weather side of hill faces. When tliis is so, the Grouse collect on them ; but as these exposed tracts are always on the weather side, and almost always on the shoulder of a hill, it is usually the worst heather which is exposed. The lee side is probably buried deep in snow. ' "Annals of Scottish Natural History," vol. vii. p. 27. - Chaj). xix. jip. 414 d seq. CAUSES OF MORTALITY IN THE RED GROUSE 177 Attention Las already been drawn to the benefit derived from sheep and deer in time of snow, owing to the surface of the snow being broken by their tracks. But although the heather may be exposed, and even though oats and corn may have been put down in abundance for the birds, the most important step has often not been taken to relieve the necessities of starving erit iu time Grouse. They must have grit, for without grit it is almost useless ° ™°^' to put down corn. This was realised and put into practice in the snowstorm of 1881 ; but only by very few. Corn was put down here and there for the ravenous birds, and though some of it was eaten it was evidently not what they were most eager to obtain. On one moor, at any rate, men were then sent out with shovels, not merely to expose the heather, but to open up the "scrapes" along the road sides all over the moor, and thus to expose fresh grit. Every day new grit was laid open and rotten quartz and sandy rock were broken out, and each day a fresh supply was needed. Grit, therefore, was what the birds were really starving for, and it was the want of it that rendered them incapable of dealing with hard corn or winter heather. With good quartz grit they can deal with almost anything, even the very woody heather that appears above the snow ; without grit they will starve. Any one may assure himself of this by examining the winter crop-contents of the white-winged Willow Grouse or "Rype" of Scandinavia — the bird which decorates our poultry shops as "Ptarmigan" in winter. It is quite wonderful to see how excellent is the condition of these birds, living as they do on hard wooden alder twigs and alder buds, woody dwarf willow twigs and old rank heather. Their crop contents are extraordinarily hard and woody and uninviting in appearance, and yet with good quartz grit it is all ground up and utilised.^ Another cause of death to Grouse is the ravages of birds and beasts of prey." -,. Deaths also occur amongst Red Grouse owins; to the antagonism which exists between the male birds of Blackgame and Capercailzie, and those of the Red Grouse. The two former have been blamed for the disappear- Blackgame ance of Grouse from certain parts of the country. John Colquhoun, caper- speaking of the decrease of Grouse in some districts says: " This °'^'^^'*^- may in part be attributed to the advance of cultivation ; but I cannot help ' Vide also " Experiments on Effect of Grit Starvation," vol. ii. Appendix F ' Vide chap. xx. pp. 443 et seq. VOL. I. M 178 THE GROUSE IN HEALTH AND IN DISEASE thinking the Blackgame have a good share in driving off the Grouse, as I know of one instance where the former were killed off, and the latter again returned to their old haunts. I believe it is also more than suspected that the Capercailzie, wherever they are introduced, have a great inclination to dispossess both."^ The conditions have altered much since this was written. Large tracts of Blackgame country have been drained and put under cultivation ; and Capercailzie have in many places again become abundant after a temporary extinction. Planting has become much more general, and the presence of young larches often determines the movements of large numbers of Blackgame. Corn feeding is a habit which has become general amongst Grouse and Blackgame wherever the lie of the laud permits, or the condition of a moor Corn feed- facilitates it. It is often mentioned as an accompaniment, or a cause, '"g- or a forerunner, or a consequence, of " Grouse Disease." The opinion of gamekeepers on the subject is about equally divided ; some say that it does the birds more good than harm, and others say exactly the reverse. Some again say that it does them neither good nor harm, and others that it is a sure precursor of disease. Occasionally yet another suggestion is made which appears on the whole to meet a certain proportion of cases, namely, that in certain districts the weaklings alone are to be found upon the stooks and stubbles, or, in other words, that corn feeding is a consequence of sickness, not a cause. Generally speaking, in districts where large packs habitually come upon the stubbles, it is probabl)^ because they have insufficient food upon the moors. Grouse when feeding on the stooks are generally not only healthy but wild, until they have filled themselves with corn, when their habitual weariness often seems to leave them. This has long been recognised, and in Adam's " Reminiscences," for example, we find the statement that " Grouse, when they get on the plough are sometimes very stupid." ' A case in point occurs in the extraordinary series of deaths from collision in Blackgame which has been described above.^ Something connected with the corn upon which the birds were feeding seems to have been the cause of their incapacity. Corn feeding then is customary with healthy Grouse on some moors much more than on others ; but the evidence seems to show that when sick birds appear ou the cornfields they are there because they are sick — not that they become sick as '.lohu Colquhoun, "Moor and Loch," p. 202, note. '■* Adam, "Reminiscences," p. 25. ^ Vide -py). \bSi et seq. CAUSES OF MORTALITY IN THE RED GROUSE 179 the effect of having been upon the corn. St John notes that on August 12th, 1847, during a severe epidemic of disease in Morayshire, Grouse were feeding in numbers on unfilled green oats in the small fields near the moor. This, he says, he had never seen before, though he was accustomed to see Grouse flocking to the stubbles in the autumn.^ Sickly birds found feeding on the stooks were forwarded for examination in 1908, birds seriously diseased with Cobbold's Strongylosis, wasted piners that could hardly fly. These were probably sick birds that had been crowded out from the good feed on the moor by the healthier birds which live there in packs, and only occasionally make a raid upon the corn. Possibly the stubble fields may become dangerously infected ground if sick birds frequent them even in moderate numbers. They may con- .,,.,.„ J J Dangers of taminate with their droppings far more corn than they can eat, and com feed- healthy birds may thus run a risk if they make their visits too frequently. It is perhaps in this way that the idea originated that overmuch corn-feeding is a precursor of disease. The following extracts bear out this view of the matter : — Macdonald quotes as follows from a pamphlet written by Mr William Colquhoun of Ross-shire in 1858 : — "The Grouse have fed a great deal ou the stooks durino- O O the disease (1854-1856) ; and on the stubbles after the corn was stacked ; and also in spring on the sown corn. This year (1858) the Grouse did not come to the corn as in former years." (The disease had then quite disappeared.)'" Again Colquhoun says that Grouse thrive in confinement when fed on corn ; but allows that their greed for corn increases in disease years. He thinks that possibly they are upset by eating damaged and unwholesome heather, and are driven to stook and stubble for a sufiiciency of food.^ Speedy, too, wTites as follows : — "An excessive consumption of corn by the Grouse species, particularly in wet seasons when the harvests are late, has been assigned as a cause of the ' Grouse Disease.' " ^ But he goes on to say that hand-reared Grouse can live for several years in perfect health without seeing anything but corn ; and that whereas on the Dalnaspidal and Rannoch moors the birds were too far from cultivation ever to see corn, yet they suff'ered badly from disease in 1873. ' Charles St Johu, " Natural History and Sport in Moray," p. 202. Edinburgh : David Douglas, 1882. 2 Macdonald, "Grouse Disease," p. 123. William Colquhoun, "Remarks ou the Decrease of Grouse •and the Grouse Disease," p. 29. Edinburgh : Edmonston and Douglas, 1858. ^ Colquhoun's Pamphlet, p. 30. * Speedy, "Sport in the Highlands and Lowlands of Scotland," p. 200, 180 THE GROUSE IN HEALTH AND IN DISEASE As with theories based on the belief that Grouse feed on frost-bitten heather, so with those that are based on their feeding upon corn, very little actual evidence is brought forward from post-mortem, examinations to show that they suflFer any harm at all from the latter food, or that they ever under any cir- cumstances fill their crops with the former. In the examination of some score of birds whose crops or gizzards contained traces of corn, only one or two showed any evidence of damage that could be directly attributed to its presence. These cases are more fully discussed in another chapter.^ Some of the birds were obviously piners that had been sick for a considerable time, and there is no doubt that their visit to the cornfields was to some extent involuntary for the reason that they found themselves unable to hold their own with the packs of healthier birds upon the moor. To some extent also no doubt it would be inevitable because from sheer weakness each flight would tend to bring them nearer to the lower cultivated ground. But this use of cultivated ground as a congregating area for sick birds depends largely upon its position with respect to the moor. If even a few habitations intervene, the Grouse, whether healthy or unhealthy, will hardly ever visit the corn, except under urgent pressure of starvation. Conditions very conducive to corn feeding exist in parts of southern Perth- shire, where the high ground runs in long and comparatively narrow ridges, while the valleys between the ranges of hills contain open areas of farmed arable land right in the very midst of the lower beats of the moors. For many reasons such low ground, whether farmed or not, must always be to some extent less healthy than the high ground, and the cornfields the least wholesome parts of all. First, because all the weakly birds on the moor tend to leave the high ground for the low, thus turning the stubble fields into concentration centres. Here, too, large packs of healthy birds making raids from the high ground not only themselves foul the lower ground with an excessive amount of loose dropj^ings full of nematode eggs and unhatched larvae, scoured from them by the irritating corn husks, but also run a great risk of filling themselves with corn which has been fouled by the convalescent, sick, and more permanently diseased occupants, whose droppings are even more abundantly full of nematode eggs than are their own. This is no doubt the point to which Colquhoun refers when he says : " My opinion is that corn is very unwholesome food for Grouse. Let any person examine the ' Vide chap. iv. pp. 81-82. CAUSES OF MORTALITY IN THE RED GROUSE 181 droppings of Grouse when fed on corn, and they will find them similar to tar, but rather browner in colour." ^ Such droppings are not so abnormal as Colquhoun believed, coming as they do direct from the cteca ; but they are full of the ova of Trichostrongijlus, and are thus a menace to the health of other birds frequenting the same feeding grounds. Low ground such as this in southern Perthshire must thus have a tendency to become thoroughly infested with the eggs and larvEe of threadworms, as well probably as with the eggs and cyst-bearing hosts of the tapeworms. The higher ground on the other hand has a tendency to get rid of these eggs and larvae by natural drainage at the expense of the lower ground. Every spate must wash down millions of nematode larvse from the higher to the lower ground, where often there is little natural drainage, and the artificial drainage is inadequate. Turning now to the dangers and risks attendant upon the natural processes of production and moulting, we find that the exigencies of courtship, mating, and moulting in the male, of moulting, the laying of eggs, and the Riskgof hatching out and rearing of a brood of chicks in the female, tfoj™'^"''' constitute the sequence of a taxation which bears heavily upon the processes. Grouse. It is worth while to look at them in detail to see to what extent each may fairly be burdened with responsibility. If an inquiry is made into the cock bird's life he will be found engaged in constant vigilance and warfare from the time of pairing, generally about the end of February or March, onwards for a month or two at least. The battles are more bloody and more disastrous to the weaklings than among cocks is generally supposed, and many of the half-starved and parasite- infected cocks, the so-called cases of "disease" found dead along the burns, have really been killed in fighting. It is a fact, testified by more than one reliable gamekeeper, that two or more healthy cocks will sometimes set upon and kill a weakling before they settle their own dispute ; and of the urgency of their own dispute the following quotation by Macphersou in the Fur and Feather Series aff'ords a good example. He quotes a Perthshire keeper, who " saw two male Grouse engaged in combat, so completely blinded by fury were the birds that they dashed against the wall of a stone building, one of them killing himself with the impetuosity of his flight." " In the same work 1 Colquhouu's Pamphlet, pp. 29, 30. 2 Macpherson, Fur and Feather Series, " The Grouse " p. 32. 182 THE GROUSE IN HEALTH AND IN DISEASE Mr Stuart- Wortley writes : " In the pairing season the old warriors come down from the heights, fight with and vanquish the younger ones, and absorb the young hens."^ Such efforts combine to bring to an end a very large proportion of cock birds which are more or less exhausted after the winter by poor feeding and the loss of strength due to the presence of intestinal parasites. Then follows the moult, an exhausting process under the best conditions, Moulting ^^^ ^^^ ^'^^ which nature generally makes provision by laying in a in tbe cock. g^Qg]^ of subcutancous fat. All this is consumed during the growth of the new feathers. But in the case of an ill-conditioned Grouse the moult commences with an insufficient supply of fat from which to draw for the growth of the new feathers. The result may be a complete failure to rise to the occasion ; or, if the failure be only partial the old feathers will be retained to some extent, and the new feathers will come slowly, poorly, and sparsely. Bare legs and a poor-looking mixture of old and faded feathers, with a more richly coloured new one here and there, produce a seedy, chequered-looking bird, and to this must be added an air of exhaustion and malaise. Occasionally in the male the summer change of plumage is not completed even by autumn, and feathers of three different plumages may then be found on a single individual. But as the season advances, and good food becomes more abundant, by degrees the moult is completed in a more or less satisfactory manner. The chief troubles are then over for the cock, and he gradually improves in condition to meet the ensuing winter. But now to consider the hen, whose lot is certainly less enviable than that of her mate. She also may have struggled through the winter, and while the Taxes to cocks fight over her is quickly putting on fat for an early moult. She hen is makes an almost complete change of plumage before laying her eggs su jeo . j^ April ; and in this she must consume a jjortion of her strength. She recuperates in sitting, but feeds only scantily the while. Then her troubles begin to be more pressing, especially if by any mishap she loses her eggs and has to lay and sit a second time. If, however, by the end of June she hatches off, she must still be constantly on the watch for danger to her chicks. In July she has to moult again. Little wonder that by August she is sometimes reduced to the con- dition of a " piner," or that, when the shooting season comes, she is discarded from the day's bag, to be submitted for examination under suspicion of " disease." It is the same story precisely as in the case of birds handicapped for life ' Macpherson, Fur and Feather Series, " Tlie Grouse," p. 147. CAUSES OF MORTALITY IN THE RED GROUSE 183 through having been hatched late in a second brood. In the one case the birds are full grown and healthy to begin with, but have been unable to stand the strain of breeding and moulting. In the other case they have never had a chance to become full grown. In either case the course of natural taxation is the same, the parasitic infestment is the same, and the final result to the bird is the same. The only thing which differs is the primary cause of weakness, and this may be one, or several, of a very considerable- number that lie in wait for the life of the Red Grouse on every moor. Of accidents which may happen in the process of laying, there is ona which is well known in captive birds, but must be rare in nature, namely, a shortage of lime rendering the eggs deficient in shell. Soft- "goft shelled eggs not only fail to stimulate the muscles of the oviduct, but ^^<^"" give them no purchase upon which to act. The consequence is that the egg is not expelled, but is broken in the duct, and is followed by other eggs until the bird dies either from exhaustion or from a rupture of the oviduct involving the peritoneum. Soft-shelled eggs in wild birds generally appear in a second clutch laid shortly after the loss of the first nestful. Gastro-uterine gestation must always be rare, but one well-marked case in a Grouse was sent up for examination. The egg, when shed by the ovary, failed to enter the open upper end of the Fallopian tube, and so passed into the body cavity. By causing irritation there it became adherent "terine . . . gestation. to the peritoneal covering of three portions of the gut. The adhesions formed a firm support, and presumably the egg was for a short time carried safely. Eventually, however, it was broken in the peritoneal cavity, and the bird was shot, and owing to her unwillingness to take flight was forwarded as a case of suspected disease. Disease of the skin is a very rare thing in wild Grouse, and Diseases of generally results from the irritation produced by innumerable ectozoa, ^^'^ ^^'°" such as ticks and lice. No. 1634 was an adult hen Grouse of 20 ounces, shot on August 12th,. 1908 in Lanarkshire. The bird was very unprepossessing in appearance, as the feathers had failed to make their way through the skin of the head and neck especially, and to some extent all over the body. The skin was of a very deep yellow colour, and there were sebaceous cysts of varying sizes scattered all over the bird, and so thick on the head and neck that hardly a feather appeared. The gamekeeper's view was that it looked " like a hen that 184 THE GROUSE IN HEALTH AND IN DISEASE liad sat herself out on frosted eggs." There was no other abnormality dis- covered except the large size of the spleen which measured 20 mm. in length and 11 mm. in thickness. It is diiticult to give any reason for this occurrence of sebaceous cystic disease of the skin. No other case of the kind has been brought to the notice of the Committee. It is somewhat analogous to acne, and it may pos- sibly have been preceded by an eczematous irritation of the skin brought about by Ixodes, the Grouse tick ; it resulted in any case in the failure of feather growth and disease of the glands which should have assisted in the process. The only other case which resembled it somewhat was Grouse No. 1792, where Ixodes and Goniodes had again produced a great number of scabs and sores and warty excrescences all over the face and head, and especially in the neighbourhood of the ears and eyes. CHAPTER IX " GROUSE DISEASE " History of "Grouse Disease" with an account of the woyJc of the "Grouse Disease" Inqimy, in resj^ect of 2)^'ei'ious tvorh done hi/ Professor Klein, Dr Cohbold, and others. By Edward A. Wilson and A. S. Leslie "Grouse Disease" in its epidemic^ form has become a serious matter only since the Grouse has come to be of importance in the economic management of estates in England and Scotland. Careful protection, improved conditions of food caused by heather-burning and drainage, and the removal, as far as practicable, of all animals that seriously affect the increase of the birds, are some of the artificial i,.. Grouse means by which moors have become more heavily stocked with Red dueTopro Grouse than was the case under more natural conditions. To this ^^^ct'O"' heavy stocking, combined sometimes with unfortunate natural conditions, but oftener with injudicious management, have been attributed the outbreaks of epidemic disease which have periodically visited the majority of Grouse moors. In other words "Grouse Disease" has always been considered to be intensified by artificial conditions. It is doubtful whether this view is correct ; as early as the end of the eighteenth century we have records of serious mortality amongst Disease the Grouse in certain districts, and "Grouse Disease" undoubtedly eighTe'euth occurred in the earlier part of the last century, long before the artificial '^"^"^"''y- conditions had become established. It is therefore probably not correct to say that the first predisposing cause of " Grouse Disease" was protection leading to overstocking. The question is really ' The familiar word " epidemic " is used tliroughout tliese volumes to signify outbreaks of specific diseases among Grouse in place of the more correct term " epizootic." 185 186 THE GROUSE IN HEALTH AND IN DISEASE of academic interest, since the artificial conditions are now firmly established, and it might be profitable to consider the other theories which have been put forward as to the predisposing causes of disease. Predispos- Such theories are numerous, and every one of them has at one time or' Grouse ^^ another been promoted to the rank of "the real cause," the acting Disease." ^^^-^^ primary cause, that is to say, of so-called " Grouse Disease." Before discussing their relative importance, however, it will be well to mention shortly what is known of the earliest appearance of the disease, and of its distribution in time and space. Among the earliest recorded outbreaks of disease about the beginnine of Ea^riy l^^st century, Macdonald, in "Grouse Disease," says : "It is now (1883) diseast^n^ eighty years since the alarm of ' Grouse Disease ' was sounded in this Grouse. country." ' Speedy says : "The first time ' Grouse Disease' attracted special attention was in 1838. Prior to that date it was not unknown in Scotland; but it had not assumed the proportions of a malignant epidemic. "Even in 1838 and for several years afterwards, it was much milder in its results than it has latterly become. In 1867 it seems to have developed a most destructive form, attracting very general attention. Prior to that it was comparatively local, decimating the birds in certain districts, and leaving other districts untouched." ° Howard Saunders says : "As long ago as 1815 a severe outbreak in the Reay country, Sutherland, was on record."^ Mr Woodrufie Peacock in a pamphlet on " Grouse Disease " writes : " Old Moor Keepers have told me that their elders knew it as a slight and local trouble quite 50 years before 1847," i.e., in 1797.'' And finally, in the MS. Records of Bolton Abbey, it is specifically mentioned as a "fatal disorder" in 1822 ; though as early as 1809 and 1811 there are records of "no shooting" — accountable in all probability to disease. Of the distribution of "Grouse Disease" in space it is more diflBcult to speak Distribu- shortly, and the question deserves very close consideration. Not "Gro°use ^^U ™uch had been made of the subject up to the time of the Disease." commencement of the present Inquiry. It may be of use, however, to give an idea of the lines upon which the Committee has been working. ' Macdonald, "Grouse Disease," p. 112. ' "Sport ill the Highlands and Lowlands of Scotland," p. 184. ' "Zoologist", 1887, p. .30-2. ■* Rev. E. A. Woodruffe Peacock, "Grouse Disease," p. 12. "GROUSE DISEASE" 187 An attempt has been made to work out the distribution of disease in Grouse, both in time and in space, by first collecting records from every possible source, and as far back in time as it is possible to go. Each record is then allocated to its proper position on a map for its own proper year. By having a separate outline map of the British Isles for each year, on which every outbreak and every occurrence of disease is marked in red, it is possible at a glance to arrive at certain conclusions, e.g. : — 1. How the incidence of disease changes from one set of counties or one district in one year to another set of counties or to another district in the next year ; thus the track of the epidemic from year to year can be distinctly followed. 2. The frequency of disease in each district is seen at a glance, and its rise and fall during the years which intervene between the periodic outbreaks can be followed. 3. The disease - incidence of each year can be compared with its wea.ther record, and conclusions thus may be drawn regarding the predisposing causes, as well as the method of dissemination. 4. By combining a large series of annual disease-records on one map an idea is obtained as to which areas suffered most, and whether any areas are disease-free. 5. Such a combination of annual disease-record maps can be superimposed upon similar maps showing rainfall, watersheds, heights above sea-level, and surface soils or sub-soils, and so it becomes possible to recognise whether disease is in any way connected with one or other set of physical conditions.^ " Grouse Disease" has long held the attention of many observers. Sportsmen and naturalists have done much for the field work, but the laboratory work has been less popular. Klein, Cobbold, Farquharson, Colquhoun, p,.evious Andrew Wilson, and Young have all contributed towards an under- ^°!?Q.ro"se standing of the pathology of " Grouse Disease," while Macdonald, Disease." Macpherson, Stuart-Wortley, Adams, Speedy, Teasdale-Buckell, and a host of other naturalists and sportsmen have supplied a large collection of interesting facts and observations, and an almost equal number of hypotheses and theories to account for them. It will be of use first to discuss the conclusions at which various writers have arrived, and as Klein's work stands out pre-eminently, and includes so great a proportion of what was known about " Grouse Disease" at the time, the simplest course will be to take his conclusions first. ' For the results of this l)ranch of the Inquiry, vide vol. ii. Appendix I. 188 THE GROUSE IN HEALTH AND IN DISEASE Professor Klein came to the conclusion that there was a disease amongst Grouse which took the form of an acute infectious pneumonia, and Professor _ "^ _ Klein's con- was characterised by the presence in the lung of a specific bacillus of elusions. J f or the B. coll group. The disease had, he believed, two classes of victims, one which died rapidly in plump condition and fine plumage, and another which died slowly with emaciation. He puts on one side the whole question of parasitic intestinal worms as having no particular connection with this epidemic pneumonia, and no causal connection with the mortality. Further, he agrees with the views of Dr D. G. F. Macdonald, and allows that Dr R. Farquharson was the first (in a letter to the Lancet, September 1874) "to state the opinion that the 'Grouse Disease' was of the nature of a contasrious fever." Dr Farquharson's view as given in Macdonald's " Grouse Disease," was that the malady resembled an infectious or contagious epidemic fever. He considered that the finding of dead birds, " some plump and in good condition, and some reduced to skeletons," was in favour of the view " that the disease is of a specific or constitutional nature."^ Klein disagreed with Dr T. Spencer Cobbold's view that the epidemic "Grouse Disease" was due wholly to the presence of nematode worms. Dr Cobbold's view, was that "in the present epidemic" (1872), the disease was " entirely due to parasites," and that " the occurrence of these parasites in the intestines of so-called healthy Grouse does not destroy the notion DrCob- „ . . boids con- of disease from this source." " A strong bird," he says, " will overcome or elusions. ..... resist the irritation set up by the presence of hundreds of entozoa ; while a feeble bird, or one attacked before it is perfectly grown, will more or less rapidly succumb to the invasion. On these and other grounds, therefore, I do not hesitate to express the opinion that the present Grouse murrain is due to parasites. The irritation, probable distress and subsequent emaciation of the birds are readily explained by the presence of hundreds and thousands of strongyles; and the mere circumstance that these parasites are very small, is quite sufficient to account for the fact that investigators have hitherto over- looked them." " "In one extreme case," he continues, "I particularly noticed a remarkable gorged or distended condition of the csecal villi, such as would result from continual irritation set up by parasites in overwhelming numbers. . . . There 1 Macdonald, "Grouse Disease," p. 129. 2 T. Spencer Gobbold, M.U., F.L.S., F.R.S. "The Grouse Disease," p. 1'). London : The Field Office, 1873. "GROUSE DISEASE" 189 was no rupture of the capillaries, and consequently no extravasation in the cajca or in any part of the intestinal canal. That this congested state of the villi was due to the strongyles appeared the more certain, since the turgidity was only marked in that part of the cajcum where the strongyles were crowded together." ' Dr Cobbold considered that the diliercnce observed in the intensity of the disease during various epidemics might be partly accounted for by the presence of tapeworms and threadworms in varying proportions in the same Grouse, but that the strongyles were " sufficient by themselves to cause the death of the host" without the "assistance of a second kind of parasite." - Klein too recognised, not so much a different type of disease in diflferent years, as two distinct phases of the same disease in the same epidemic, namely, that which is so acute as to kill birds in good condition without giving them time to lose flesh, and that which is so much less acute that it gives its victims abundant time to become emaciated before death. Cobbold, however, differed from Klein in one important respect, viz. : — that he distinctly indicates that he did not observe any example of a Grouse dying in good condition and without loss of flesh. Neither Klein nor Cobbold suggest that they had any suspicion that they were dealing with two distinct diseases. Taking all these facts and opinions into consideration, the Committee at an early period adopted the provisional view that Klein and Cobbold com. had before them Grouse dead from two distinct diseases — (l) plump and ,"ovUiionai well-conditioned birds which had died of an acute infectious pneumonia, ^]s^~t^° i.e., the acute form of Klein's "Grouse Disease"; and (2) emaciated diseases. piners which had died of the results of extreme parasitism, i.e., of Cobbold's Strongylosis. The Committee kept in view, however, that since there is no reason why a bird already dying of Cobbold's Strongylosis to recondie should not become infected with, and succumb to, Klein's infectious ,?'f °'^ •., pneumonia, it was possible that the piners examined by Klein might Cpbboid's also be cases of the acute infectious pneumonia, which had stepped in and made an end of their already diseased existence. It would have been obvious to Dr Cobbold, if he had ever really seen a clear case of a Grouse which had died in good condition, well up to average weight, but with pneumonic lungs, that its death must have been due to some more acute cause than the mere presence of nematodes in the gut. » Cobbold, " Grouse Disease," pp. 24, 25. 2 /j^y_ 190 THE GROUSE IN HEALTH AND IN DISEASE It was clear that Dr Cobbold's experience had lain entirely with emaciated birds, while Professor Klein as we know observed birds of all kinds ; but always from moors where the pneumonic disease appeared to be rampant. It had been generally noticed in past epidemics of disease that the first Character victims werc of the emaciated type. It was only in the later stages of past epi- . . . demies. of the Outbreak that birds in apparently robust health were said to have been found dead often " sitting on their nests." The Committee believed it not unlikely, judging only from the limited evidence before them, that the reason of this was that the acute pneumonic disease picked out first and made a clean sweep of birds already emaciated by Cobbold's Strongylosis. These piners would naturally be concentrated on the lower ground, and since their power of resistance to disease would be low any infection would naturally spread rapidly amongst them, while the more healthy birds on the higher beats, with a greater disease-resisting power in them, would be less prone to take the infection immediately, and also would be less readily discovered on the higher ground, even when the disease had proved fatal. This hypothesis appeared to account for a clean sweep of the piners all Might be over the moor, and for the distribution of their bodies in large forby'both numbers along the burn-sides, before the disease could reach the Cobbold's healthy Grouse on the upper ground, or at least before the dead theories. bodies of Grouse on the high ground were discovered in any number. There appeared therefore in the early days of the Inquiry to be some reason for suspecting that both Klein and Cobbold had confused two separate diseases under the common title " Grouse Disease." And with regard to this point the Committee were probably in a better position to judge than those who had preceded them, in that the latter had begun and ended their work amongst innumerable dead and dying Grouse, the victims of a chronic wasting form of disease, often, it seemed, inseparably mixed up with the victims of a widespread epidemic of acute pneumonia. One thing was quite certain, that whereas the Committee had seen during Only one the first three years of the Inquiry extensive mortality amongst Grouse disease causcd by some agent which acted slowly and produced " piners " by^Com- ouly, they had not seen anything at all like an epidemic of acute inittee. ^j, jjifgctious pncumonia. It followed therefore that if the rapid "GROUSE DISEASE" 191 death of birds in good condition was typical of Klein's disease no case of Klein's disease had yet been seen. At this date the only form of disease observed was a very widespread mortality of "piners" owing to what appeared to be a form of starvation resulting from a chronic congestion of the csecal mucosa. This Character " '^ oi disease condition of the mucosa was produced by an excessive number of observed . .J. . byCom- the nematode worm known as Trichostroyigylus pergracihs m the mittee. caeca, and was quite comparable to the form of "Grouse Disease" described by Cobbold. The view that two distinct forms of disease had for many years past been confused under one term was supported by the literature of the Committee's '■ '^ "^ _ view sup- subiect, for all previous writers on Grouse and "Grouse Disease" had ported by . . . , 1 T *'^*^ litera- referred to a difference in character to be noticed between the disease ture. outbreak of one year and that of another, or between the appearance of the victims at one season and another in the same epidemic. By adopting the view that two distinct diseases had been confused, much of the disagreement which had been in evidence from the earliest days, as to the predisposing causes of " Grouse Disease," could be explained. The following abstracts suggest that there were two different agencies at work destroying Grouse in large numbers. William Houstoun of Kintradwell, Brora, for instance, says: "At that time it took the tapeworm type, and the birds all came down to the seashore to pick up particles of salt ; but, when the disease next appeared, it had a different form, and I fear we are as far as ever from a solution of the cause. I opened three birds in the last stages of the disease " (the pining form) " and they all presented the same appearance. The liver like a clot of coagulated ink ; intestines distended with a yellow feculent matter ; and crop full of undigested but fresh and green heather tops."^ These were presumably cases of Cobbold's Strongylosis, since the distension of the intestines "with a yellow feculent matter" suggests the appearance characterising the cseca in that disease, and the victims were all piners. Again, Macdouald, in his book on "Grouse Disease," described the earlier stages of the epidemic as being much more virulent, the birds being found dead and dying in numbers by the water-courses, "which latterly was not the case." The plumage in the earlier attacks looked different, the feathers were dirty ' Macdonald, "Grouse Disease," p. 140. 192 THE GEOUSE IN HEALTH AND IN DISEASE and draggled — an appearance which was " latterly not seen in diseased birds." ' And again, quoting from "Land and Water" (1867), he says that "one striking difference between the disease of 1867 and that of former years was that the dead birds . . . picked up this season were so plump and in such excellent plumage that they had the appearance of healthy birds ; whereas in former years the diseased birds were most characterised by disordered plumage and attenuated bodies."^ From this the Committee surmised that the disease which occurred in 1867 was Klein's pneumonia ; while in the previous records the birds had been victims of Cobbold's Strongylosis. This provisional view was again borne out, by a letter written by Mr Macdonald to the Times, May 12th, 1873, which ran thus : " It seems that disease of an exceedingly virulent kind prevails in all parts of the Highlands, and in a form hitherto unknown. ... In 1847, 1856, and 1865 the infected Grouse exhibited a ' dull disordered plumage and attenuated bodies.' ... In June 1867 they showed good plumage, a healthy ajipearance, and were perfectly plump, although the liver was soft and discoloured. This year (1873) they are beautiful in plumage, but wasted to skeletons . . . and with full crops." ^ This occurred evidently in later autumn, since mention is made of the large quantities of berries in their crops. All these quotations seemed to point to the fact that in 1856 and 1865 there was an excessive mortality from Cobbold's Strongylosis ; whereas in 1867 there was an epidemic of Klein's acute infectious pneumonia. In 1873, the birds which were seen late in autumn were presumably recovering, thanks to a full diet of berries, or, if found dead, were to be considered cases of Cobbold's Strongylosis killed by Klein's pneumonia. They may have survived an attack of acute pneumonia which the Committee were prepared to believe had raged that year, but they certainly were also victims of Cobbold's Strongylosis ; and the fact that their plumage was in good order seemed to show that they were at any rate sufiicieutly convalescent to complete the growth of their winter plumage after moulting. Macdonald writes : " We have ourselves frequently picked up dead Grouse perfectly plump, and in excellent plumage one season, and in the next season found diseased birds with attenuated bodies and dull disordered plumage."* ' Macdonalfl, " Grouse Disease," p. 127. ° Ihid., p. 155. ' Ibid., p. 155. Ibid., p. 131. "GROUSE DISEASE" 193 Again, in Adam's " Reminiscences " we find : " Disease in this attack (Dalnawillan, 1882) was very difi'erent in its aspects from former attacks. It came on very suddenly, sharp and decisive ; but on this occasion I have no doubt but that it had been hanging about all through 1881, and also in the spring and summer of 1882, steadily wearing away the birds bit by bit."^ The distinction is markedly contrasted by Adams in his book, and the incidence in each case is well described. Tom Speedy in " Sport in the Highlands and Lowlands of Scotland" writes : "The epidemic assumed two different forms. In some cases the birds were draggled, wasted, and emaciated, bare about the legs, and indicating ... a long continued or fatal disease. At a more advanced period of the season they were found dead in beautiful plumage, with fine feathery legs ; and the red above their eyes unsullied and as bright as vermilion. In many cases they were seen the one day seemingly in perfect health, and the next day stifii' and cold in excellent condition." ^ Enough has now been quoted to show that in the minds of many observers there has been for years the suspicion that the diff'erences observed were not merely two phases of one form of sickness, but two distinct diseases. And it was on this assumption that the Committee at first commenced their investigation. The widespread idea that tapeworms are at the root of one form of trouble is perhaps natural, considering that it is common knowledge that in some animals they are the cause of serious wasting. Moreover, the very Tapeworms first thing that appears when a Grouse is opened up, whether purposely eau°e^of ^ or accidentally, is a mass of large white tapeworms. What could be '*^'^'^*®- more natural, since the bird is wasted to skin and bone, and tapeworms are found in large numbers, than to consider the one to be the cause of the other. But if only threadworms were as conspicuous as tapeworms, outnumbering them as they often do, to an almost incredible extent ; or if some distinction had been earlier recognised between the main gut of the Grouse and its caecal appendices, there would before now have been a strong following of Dr Cobbold, and the pining form of disease would be more readily associated with the presence of the smaller worm. The Committee's provisional belief in the existence of two distinct kinds of 1 Adam, " Reminisceiices," p. 75. !> Op. cit., p. 185. VOL. I. N 194 THE GROUSE IN HEALTH AND IN DISEASE No case of " Grouse Disease" appeared to be justified up to a certain point, but Klein's disease yet as there has as yet been no outbreak of Klein's epidemic pneumonia observed. within the Committee's knowledge, it was impossible to speak positively upon the subject. Klein, of course, had "piners" to work with as well as "birds that died in good condition " before they had time to pine ; but as already stated he came to the conclusion that they exemplified two phases of the one disease. It appeared quite reasonable to believe that in an epidemic of the infectious pneumonia some of the birds might survive long enough to become piners ; therefore the Committee were prepared to accept Klein's explanation in so far as it applied to the birds which he had the opportunity of examining. But it could never happen that uncomplicated cases of Cobbold's Strongylosis should die plump and in good condition. Loss of All birds dying from Strongylosis must be "piners," because invariable their death results mainly from an inability to absorb nourishment accompani- ment of owing to the cajcal mucosa being damaged. The consequent emacia- Cobbold's . . . ^ . , -, . . disease. tion IS a Sine qua non in the diagnosis. The weak point, as it appeared to the Committee, in Klein's argument was that he makes no adequate mention of the csecal lesions caused by the Weak point Trichostrongylus , lesions which in the majority of adult birds examined theory. by the Committee have been the most prominent, indeed the only prominent feature upon dissection, and which the Committee believe to be at the root of the whole question. Before proceeding further to discuss this point it will be well to look into the accounts of dissections which have been recorded from time to Records of time (many unfortunately in the most cursory manner), with a view dissections, to Seeing what pathological lesions were found to account for death. Klein's work is again in many respects far ahead of all the rest ; and as it is necessary to go into it in some detail it will be better first to glance at the work of others. Dr Cobbold's notes on the pathologj?^ of " Grouse Disease " have already been quoted ; ' but reference must again be made to a description which he gives of the cteca in an " extreme case " dissected by him. ' See p. 188. "GEOUSE DISEASE" 195 " In one extreme case," he says, " I particularly noticed a remarkably gorged or distended condition of the csecal villi, such as would result from continual irritation set up by parasites in overwhelming numbers. . . . There was no rupture of the capillaries and consequently no extravasation in the caeca or in any part of the intestinal canal." This condition of the caecal villi is very typical of extreme Strongylosis as observed by the Committee, just as the same engorged condition to a lesser degree of the intestinal villi is typical of Helminthiasis generally. Nor is it by any means so rare as one might gather from Cobbold's description. Yet Professor Klein makes no mention of any condition at all approaching it in character, in any of the birds examined by him, though he allows the almost universal infection by the Trichostrongylus. Professor John Young wrote a paper on Certain Aspects of the Grouse Disease, in the " Natural History Proceedings of the Glasgow University," vol. i. (quoted in Macdonald's "Grouse Disease").^ Unfortunately, he Pro- . . , . . . fessor J. does not differentiate between the different portions of the intestine ; Young. but he appears to have had a most abnormal series of birds to examine. In two of three Argyllshire birds he found general peritonitis due to perforation of the gut which must have occurred a sufficient length of time before death to allow of adhesion and short circuiting. Dr Andrew Wilson is also represented as having satisfied himself "by repeated dissections and careful observation that a markedly congested appear- ance of the mucous surface and of the digestive and respiratory tracts was almost invariably present in birds which had been found dead."' John Keast Lord and Frank Buckland are represented by the same indefatig- able collater as having "satisfied themselves that the disease was dis- john organisation of the liver accompanied by inflammation of the chest aiidR viscera." The pity is that we can never know what amount of exact ^^I'^kiand. observation these vague descriptions really covered. As they stand they cannot be considered of any value. Tom Speedy writes as follows rather more to the point : "In post-mortem ex- amination in a number of birds we discovered intense inflammation of the bowels ; while by the aid of the microscope, immense quantities of strongyle were ^0,^ discernible in the inflamed parts . . . such cases were exceptional when Speedy. contrasted with that other more loathsome form of the malady which seems ' Macdonald, "Grouse Disease," p. 141. ^ Ihid., p. 145. 196 THE GROUSE IN HEALTH AND IN DISEASE to have been muck more contagious."^ By "the other" more loathsome form of the malady he meant the acute disease which killed off birds while still in excellent condition ; and, it is interesting to note, that, during this epidemic, cases of "Cobbold's Strongylosis," such as he first described, were apparently exceptional. It is easy to see how incompatible was much of this with what the Committee had seen of " Grouse Disease" during the first few years of the Inquiry, during which " Cobbold's Strongylosis" had been in many places abundant, and Klein's •acute infectious pneumonia had been not only exceptional, but non-existent. Turning now to Klein's account of the pathology of " Grouse Disease," and remembering that he considered both the piners and the birds that died in good condition as alike victims of an acute infectious pneumonia, we find a very definite statement of pathological signs and lesions which he diagnosed as the acute pneumonic disease. " One of the most prominent pathological changes in the diseased Grouse is an acute congestion of one or both lungs, and this change, whether very severe or less severe, is independent of the presence of Strongylus."^ This implied absence of Strongylus is diflicult to accept as a fact, notwith- standing Professor Klein's statement and the general accuracy of his observations. The Strongylus is almost universally present in the Red Grouse of all ages, strongylus ^^ the Committee has been able to ascertain by the examination of some versaHn"' two thousand birds from every part of the United Kingdom. When- Grouse. g^gp ^ gg^gg occurred in which its presence was not at once evident, a special search has almost invariably revealed it. Dr Andrew Wilson came nearer to the truth of this matter when he stated that " in one or two doubtful instances only could it be asserted or suggested Dr Andrew ^^^^ uone of the Tound worms were present." He nevertheless puts Wilson. Helminthiasis aside, and believes that the " Grouse Disease " is in the main an infectious fever. He does this, moreover, with every show of good reason, and in words to which we can hardly take the smallest exception, save that he makes too light of the trouble which we now call Strongylo-sis. He says, for example : " Outside the parasitic hypothesis, applicable as that theory is to a certain class of cases, there lies, I am convinced, the great bulk of fatal instances, the exact cause of which fatality must be sought for in some lesion analogous to that involved in the idea of the epidemic theory." ' ' Speedy, " Sport in the Highlands and Lowlands of Scotland," p. 185. ^ Klein, "Grouse Disease," p. 6. ^ Macdonald, "Grouse Disease," p. 148. "GROUSE DISEASE" igr He was handicapped by this belief iu the epidemic theory, but we have to- confess that it is dithcult to accommodate his observations to the belief in Strongylosis, for he says that there was an "absence, m most eases, of the signs- of fatal parasitism, such as inanition producing the pining condition, actual perforation, morbid appearance of the muscular tissues, etc." ' For if most of the cases that he examined were marked by an absence of inanition, they differed very materially indeed from all the cases of birds found dead or dying within the years of the present Inquiry ; almost all of which were "piners" to a greater or less degree. But, writers like all other early writers, he produces no particulars as to weights, record of and in the absence of these it is impossible to accept as a fact that " inanition was absent, knowing as we now do, how exceedingly misleading are the external appearances of many of these cases. Klein did not believe in two distinct diseases, and described the autumn and winter cases as having pathological appearances identical with those found in the unwasted Grouse which had died of disease during uotrecog- the spring and early summer. He believed these autumn and winter distinct victims to be sporadic cases of " the real Grouse Disease," which occurs in the spring and early summer. Nowhere throughout his whole book can any suggestion be found that goes even so far as Dr Andrew Wilson's view, that a few birds at least may succumb to Strongylosis, or even to general Helminthiasis. Klein appears to include all the Grouse which he described with the appear- ance of a pneumonic lesion in the lung, at any time of the year, as victims of the true " Grouse Disease," and by this he meant iu every case the acute infectious pneumonia which he was the first to describe in detail, but which the Committee now believes has no existence, and was founded on a misinter- pretation oi post-mortem changes in the dead bird. What then were the appearances upon which he relied in making a diagnosis of acute infectious pneumonia ? The points He sums them up once or twice on pp. 15-19 of his book on K^iek^Tased "Grouse Disease." his theories. " The chief changes are undoubtedly those found in the lungs. " {«) In emaciated birds the disease of the lungs is, as a rule, but not without exception, not very extensive, only a portion of one or both lungs being congested. ' Macdonald, " Grouse Disease," p. 148. 198 THE GROUSE IN HEALTH AND IN DISEASE " (b) In the majority of instances in which the dead birds are found plump .... the lungs show a great deal of congestion. "The lungs show deep coloration in the greater part of either one or both organs, the hind portions being, in these cases, the ones chiefly affected ; or both luno-s are uniformly congested, being in some cases of a dark purple-red colour. " ' On microscopic examination of the lung, Klein finds " that in the con- gested parts the large and small vessels are uniformly distended and filled with blood, and that the air spaces of the more deeply affected parts are uniformly distended and filled with a homogeneous or granular exudation, or with blood, so that in these parts we have a solidification of the lung which compares with the condition known as the red hepatisation in pneumonia. There is, however, no fibrine in the form of threads noticeable in the air spaces ; the smaller air spaces contain blood en masse, while the large ones are filled with a homogeneous albuminous exudation. From this we con- clude that rupture of small vessels had taken place during life."^ To continue further with the pathological signs to which Klein has drawn attention, "the larynx and trachea," he says, "exhibit a change in the mucous membrane, which is of a dark colour, and hyperaemic, and this is the more pronounced the more marked the lung-change. The spleen is not enlarged, and appears of a dark colour. " The liver is uniformly congested and soft ; it is either of a dark red colour, or appears almost black. On microscopic examination the large blood-vessels as well as the capillaries of the lobules are distended and filled with blood corpuscles. In some cases the liver, on post-mortem examination, is blackish, or rather is of a dark olive-green colour. In these instances the liver cells appear granular and more or less disintegrating, and contain dark brown pigment granules, while the capillary blood-vessels are filled, not with blood corpuscles, but with masses of amorphous pigment, the result of stasis and disintegration of the blood corpuscles. " The kidneys are congested, in some instances leading to haemorrhage into the tissue of the kidney. " The intestinal mucous membrane shows patchy congestion, and the same is the case with its serous covering, which in most instances is congested in many places, sometimes to a considerable extent. In some cases the peritoneum appears very moist in these localities ; that is to say, there is a small amount of exudation. > Klein, "Grouse Disease," p. 15. - IhiiL, p. 17. "GROUSE DISEASE" 199 " I have seen a few cases in which htemorrhage has taken place, showing itself in the form of petechi^e in the peritoneum." * These appearances which Professor Klein believed to be diagnostic of the acute infectious pneumonia are summarised on page 44 of his book, as follows : — " The congestion of one or both lungs, the congestion of the liver, the small dark spleen, and the patchy redness of the intestine and the peritoneum," and one may add, the presence of the specific bacillus in the lung and liver of affected birds. Although the bacillus is not present in the circulating blood of birds affected during the spring and early summer outbreaks, appearing then mainly in the lungs and liver, they are to be found, he tells us, in the circulating Pl'GSGllC© blood of birds that have died in the autumn and winter. He believes, of bacillus moreover, that the latter are the sporadic cases which keep the disease lingering through the winter, ready to break out in a spring or summer epidemic, though the vitality of the microbe is such that it probably requires no such active assistance from individual birds. It will be seen that it appeared impossible for the Committee to accept unconditionally the views of any of their predecessors in the work ; but it seemed equally impossible to discredit altogether the reliability of detailed observations made by many workers of high standing. At this stage of their investigation the Committee still believed that Klein's " Grouse Disease" was an established fact (though his diagnosis might require revision), and spoke of it as the "true epidemic Grouse Disease," or "Klein's acute infectious pneumonia." At the same time, the Committee believed it to be an advantage for them to see one disease at a time, and began to distinguish Cobbold's Strongylosis as a specific disease apart from Klein's acute infectious pneumonia. The foregoing resume is necessary in order to show the position of the controversy when the Committee of Inquiry was beginning its work. It explains many of the unavoidable errors into which the Committee was led by the inaccuracy of much that had been published on the subject. Even Professor Klein's w'ork, accurate and painstaking as it was, and clear oause of as were his published descriptions of whatever he himself saw, was P^°fessor misinterpreted by him for the sole reason that bacteriology (a science ®''™'"- of which he was one of the most honoured founders) was still in its infancy. His deductions as to the disease being an acute infectious pneumonia due to a specific bacillus have now been shown to be founded upon a misconception ; ' Klein, "Grouse Disease," p. 19. 200 THE GROUSE IN HEALTH AND IN DISEASE but, in the days when he was working at the subject, no cue could have arrived at other conclusions than those to which he himself came. It is due to so great and careful a worker to say that at that time he was years ahead of any other bacteriologist. That he should since have been found to be in error merely shows how dependent is science upon the methods available at the moment, and how impossible it is for any one at any time to be certain that even the most probable explanation of observed facts is the right one. It has been thought necessary to set forth the different stages of opinion through which the Committee has passed in order to account for many mittee's provisional conjectures, since shown to be faulty, as to the cause of diagnoses death in birds that were submitted for examination in the earlier incorrect. ^ r j_i t days 01 the Inquiry. From the first it was thought advisable to acknowledge the receipt of every bird sent to the officials conducting the Inquiry, and, where possible, to account for its death or its sickness, or for any abnormality which it presented. In the earlier days the field-observers believed firmly in Klein's view that " Grouse Disease " was an acute infectious pneumonia, and in a few isolated cases they believed that the lesions described by him with so much detail were present. They thereupon made the necessary diagnosis and sent in their report, and for the next week or two awaited an inundation of dead birds showing similar lesions. But no epidemic occurred and the inundation did not happen, and by degrees it became evident that there was something doubtful about the view which had been provisionally adopted. This doubt was confirmed when the bacteriologist, Dr Seligmaun, found that the bacillus which Professor Klein considered to be the specific cause of Klein's Grouse pucumonia was in fact only to be discovered in any number found to be ^omc twclvc or twenty-four hours after death. It became gradually m'^tem'"'' clear that not only the grosser appearances in the lung which Klein change. considered to be due to pneumonic congestion, but the microscopic appearances of the lung - tissue in section, as well as the colonies of bacilli which he described and figured in the lung, were in fact only to be found some hours or days after the death of the bird. They were undoubtedly due to a post-mortem migration into, and colonisation of, the tissues in question l)y numbers of Bacillus coli which had escaped from their proper sphere in the intestine at the moment when the normal defence had broken down. It gradually began to dawn upon the Committee that the appearances in "GROUSE DISEASE" 201 the lung upon which Klein had relied in making a diagnosis of acute infectious pneumonia differed in no way from the appearances which had been g^^'^g^gj.. observed by the Committee in the luno;s of hundreds of birds found istic;s foimd J o 111 all dead dead from all causes, including Cobbold's Strongylosis, general birds. Helminthiasis, accidents, or even shot wounds. Klein describes accurately the post-mortem changes leading to a discoloration of the lungs which invariably take place. These begin, almost always, where the lung is in contact with the liver, and strongly suggest (what at first the Committee frequently mistook it for) congestion and pneumonia. This discovery undermined the faith which the Committee were prepared to place in the existence of Klein's acute infectious pneumonia, and it soon became evident that in birds obviously dying of " Grouse Disease," there was no dangerous ante - mortem infection of the lung or other tissues with the bacillus in question, and no recognisable lesion in any organ of the bird except in parts of the intestine. All the appearance of congestion and pneumonia in the lung, the "inky" or "tarry" appearance of the liver, the small dark spleen and the several other characteristics which were previously attributed to Klein's pneumonic disease, were now found to be due to 2^ost-mortem change alike evident iu diseased and in perfectly healthy normal birds. The point was further tested by taking a number of healthy pigeons, and killins; the whole of them at the same time with chloroform. The ° . Experi- birds were numbered and opened on consecutive days and the change ment in the appearance of the viscera was noted. It was evident that in healthy -Pill n ■ 1 pigeons. every case where there had been extravasation oi blood or serous Huid owing to rough handling, or damage by the knife in dissecting the pigeon, the tissues of the lung became black, and took upon themselves precisely the same appearance that is seen iu a Grouse found dead upon the moor, or examined some days after being shot. The appearance of pneumonia was evidently due to a soaking of the lung-tissue iu decomposing blood and serum, and the 2}0st- mortem colonisation of the tissues by Bacillus colt} Once this fact became clear, the Committee was no longer burdened with the task of recognising and investigating the type of " Grouse Disease " „ . , ^ t> o o t^ J r ^ Pomts to described bv Professor Klein, for it now became impossible to accept his be imesti- . . gated by explanation of the disease. This being recognised it became necessary to set the Com- IXlltJL66t on foot more detailed investigations to determine the following points : — ' vide also chap. xii. pp. 273 et seq. 202 THE GROUSE IN HEALTH AND IN DISEASE 1. To prove that the amended view of Klein's work was the right one, and that the "Grouse Disease" which he saw and described as a form of infectious pneumonia was in reality not different to the "Grouse Disease" which the Committee were seeing constantly, and were describing as Cobbold's Strongylosis. 2. To make every effort to obtain fresh and living samples of wild Grouse actually suffering from " Grouse Disease," for systematic laboratory work, with a view to discovering whether this or any other wide- spread form of " Grouse Disease " was caused by bacterial infection or not. 3. To complete the investigation of the Grouse parasites, ectozoa as well as entozoa, with a view to determining whether by any possibility " Grouse Disease " could be considered attributable to some of them, or even to one of them. 4. To investigate the blood of the Grouse in health and in sickness, and especially to try and discover the presence of toxfemia with its resultant anaemia and changes in the respective proportions of leucocytes. It was thought possible that the toxins produced by Helminthes in the intestine might be the cause of some increase in the eosinophil corpuscles. 5. To make certain that " Grouse Disease" did not result from the presence in the intestines, or in the blood, of any protozoan parasite for the transference of which we knew the Grouse had ticks, bird-lice, flies, fleas and other external parasites. 6. To make a complete and special investigation of the life-history of the Trichostrongylus pergracilts or the Strongyle of Cobbold, with a view to understanding its mode of infecting Grouse, its action when in the caecum of the Grouse, its method of reproduction, its dis- semination, and the conditions which enable it to hatch from the egg, to pass from the larval stage to encystnient, to survive on a Grouse moor, and to ensure its being swallowed by the bird at a stage when to be swallowed means completing the cycle of parasitic life, instead of being merely digested. The life history of this threadworm was obviously required in its smallest details, in order that Strongylosis might be understood. How these various questions were dealt with may now be explained. "GROUSE DISEASE" 203 During the period of the Inquiry all the birds that have passed through the Committee's hands, have been examined as carefully as circumstances allowed at the moment. Every bird, almost without exception, was dissected, and the more important points were noted and tabulated, providing in this way a very considerable mass of observations from which to deduce averages, construct tables and curves, and so obtain information which had previously been inaccessible.^ In addition to this, in the majority of the more interesting cases, parts of the various organs, as well as the contents of the different portions of the alimentary canal, were submitted to microscopic examination. The tissues were hardened and cut, and a very large number of sections examined microscopically, not by one member of the staff alone, but by a number ■of workers qualified to give an opinion upon what they saw, so that bit by bit a true reading of the observed facts was attained. One or two questions regarding Professor Klein's work were to some extent settled by the bacteriological work which Dr Seligmann carried out in the first two years of the Inquiry. Dr Seligmann, before resigning his position conclusions as Bacteriologist to the Inquiry, on leaving for Ceylon in December by^i^'cterio- 1907, wrote an interim report of his work in which he gave his ^"Sists. provisional conclusions. Dr. Cobbett and Dr. Graham Smith were then enlisted on behalf of the bacteriological work, and their results are to be found in detail in chapter xii. They came to a very definite conclusion as to the absence of pneumonia in the birds which they examined " in a perfectly fresh condition, the lungs being always pale pink in colour and free from congestion." They ascertained that the redness of the mucosa of the cseca was obviously not a post-mortem change. They concluded further that diseased birds as a rule have a very large number of Trichostrongylus, whereas healthy birds may have but few, and do not very often have a large number. They also came to the definite conclusion that " ' Grouse Disease' is not an infection with those bacteria" which find their way in limited numbers into the organs of birds which contain Ti-ichostrongylus. They have not been able to satisfy themselves that the bacilli which find their way into the organs do much harm. Some harm no doubt they do ; but how much they cannot say. 1 A complete list of all birds examined, with a note of the principal lesions observed, is given in Appendix B. 204 THE GROUSE IN HEALTH AND IN DISEASE Adam's view is that a potent cause of disease is the "constant absorption of small quantities of bacteria," hence the question put by Drs Cobbett and Graham Smith, " Is it a toxaemia caused by the poison liberated from bacteria which have been absorbed from the intestine, and which have almost immediately perished in the tissue ? " Tlieir work has all tended to the view that Klein's observations required revision in the light of modern work in bacteriology, that his deductions required amendment, and that " Grouse Disease" is not an acute infectious pneumonia. Can we then believe that there is an epidemic form of "Grouse Disease" which in spite of minute inquiry and search has eluded the vigilance of the Inquiry during the last six years ? Drs Cobbett and Graham Smith {see p. 274) go the length of saying : "It is, we suppose, just possible that we never came across the genuine epizootic 'Grouse Disease' at all." Apart from the question of whether Klein's pneumonia has any existence .„„^ in reality, all the outbreaks of disease amongst Grouse which have All " Grouse ■' ' ° . Disease" comc Under the observation of the Committee can be ascribed either either . . i • i i Strongylosis to Strono-ylosis or to Coccidiosis, the only two diseases which the or Cocci- "■^ . . , , diosis. Committee now recognise as causing widespread mortality amongst Grouse. It is quite clear that one of the most important signs of disease, whether it be Strongylosis or Coccidiosis, is a loss of weight. And this loss of condition. Loss of even to emaciation, which follows on Strongylosis, is a character to chafacLr- which fuU prominence is given by all writers about " Grouse Disease," these°^ '^"'^^ *^°"S^ no measurement of actual weights had ever been recorded so- diseases. fg^p ^^ ^g^g jjnown before the present Inquiry began its work. The omission to record weights in the past is the more to be regretted because the chief characteristic of the only other form of "Grouse Disease" which has been reported is the fact that the weight of birds that have succumbed to it remains normal. Probably one of the most persistently quoted observations, which many Theory that sportsmen and gamekeepers still maintain to be a fact, is that in some Grouse'' epidemics there is a certain proportion of birds which succumb to dieTn'giod "0 acutc and virulent a form of "Grouse Disease" that they die condition, i^gfofg ^ny loss of flesh or weight can have time to show itself, and before any change in the appearance of the feathers becomes manifest. "GROUSE DISEASE" 205 This view is founded not on actual measurement of weight, but on the bird's general appearance of good feather and normal weight, as estimated hy the observer who takes the bird in his hand when it is found dead on the moor. In most alleged outbreaks of "Grouse Disease" the birds have been collected and burned, or buried by the score in a soft moss-hag or under a rock. They were never weighed, and never carefully examined. Yet without careful weighing and examination it is impossible to come to any reasonable conclusion as to their condition or the cause of their death. The Committee's field-observer has himself been present on several occasions when such birds have been picked up and passed from one to another of the keepers and the ghillies ; full-featliered, richly-coloured hens, perhaps found almost warm but dead upon their nests. And these birds have been weighed in the hands and their weight guessed as fully normal, notwithstanding the condition of the breast, yet the spring balance has invariably proved appearances deceptive, except in the cases where accident has been the cause of death. If the case is a hen whose feathers have been recently donned for nesting a most misleading impression of good condition is given even in a wasted bird, where the plumage has not been drenched with rain or bleached by sunshine. In the cocks it is diflerent, for the feathers have not been changed for the nesting season, and the plumage is often worn and faded in comparison with the new, nesting plumage of the hen.^ It is often hard to believe that a hen Grouse which has died in full nesting plumage, however thin and poor, is not actually heavier than the dingy cock bird of the same month. And if no rain has fallen on the hen since her death the comparison between her and the cocks which are found in all stages of disease, decayed, weathered and bleached, is even more misleading. The point has now been too often tested to allow of doubt. No bird dies of Strongylosis without loss of weight. That some birds waste more and some less before succumbing to the disease is certainly true, the difference in this respect depends mainly upon the season ; yet it must be conceded that sex and individual strength also make a difference.^ On one point the Committee can speak with entire confidence. During the whole period of the Inquiry, from 1904 to 1910, there has not been a single outbreak of "Grouse Disease" in which the birds died without loss of weight. ' Vide chap. iii. ^ Vide chap. vi. p. 142. 206 THE GROUSE IN HEALTH AND IN DISEASE While, therefore, it is possible that the virulent form of disease does, in fact, sometimes occur, it is also possible that the belief in it is entirely without justification, and is the result of inadequacy in method and inaccurracy in observation. During the investigations of the Committee's observers, an interesting side- light has been thrown on a possible connection between Coccidiosis and the earlier work of Tegetmeier on pneumo-enteritis. In some Grouse-chicks dying of intestinal Coccidiosis, cysts were found in the bronchioles, bronchi, and trachea, but not in the lung-tissue itself, while the lungs of the young birds exhibited apparent symptoms of pneumonia. The coccidian cysts in the bronchioles might be capable of setting up suflicient irritation to account for the pneumonic symptoms. It is possible that there may be here some explanation of the pneumo-enteritis of earlier writers. CHAPTER X " GROUSE DISEASE " — CONTINUED — STRONGYLOSIS * Part I. — The Threadworms {Nematoda) ~ By Dr A. E. Shipley Part II.- — On the Development and Bionomics of Teichostrongylus PERGRACILIS By Dr Robert T. Leiper (I.) Family Strongylidae (i.) Trichostrongylus pergracilis (Cobbold) Synouym : Strongylus gracilis Cobbold This round-worm was first described under the name of Strongylus pergracilis (Cobbold), by Cobbold,^ whose words we quote : — " Characters. — Body filiform, finely striated, gradually diminishing in front, uniform in thickness below ; head bluntly pointed, with a simple oral aperture ; tail of the male furnished with a bilobed bursa, each half supporting four pointed rays ; spicules two, thick, and slightly divergent ; tail of the female slightly swollen above the subterminal anal orifice, rather sharply pointed at the tip ; vaginal opening situated at the upper part of the inferior sixth of the body. " Length of male \ inch to f inch ; body ^^ inch in diameter, tapering anteriorly to ^^Vir ^^^^ at the head ; greatest breadth immediately above the bursa TTjr inch. ^ The term " Strongj'losis " is employed in this chapter to denote the disease caused by Tricho- strongylus 'pergracilis (Cobbold) ; though it would perhaps be more strictly correct to name the disease Trichostrongylosis. - Reprinted with slight alterations from the Proceedings of the Zoological Society of London, 1909. 3 Cobbold " Grouse Disease," p. 16. 207 SOS THE GROUSE IN HEALTH AND IN DISEASE " Length of female mostly f inch, sometimes very nearly ^ inch ; breadth above the tail -577 inch to ttttt inch, narrowing at the extreme point to ^^xru ^^^^ ' longitudinal diameter of the eggs itItt inch, their breadth being ah> inch." Eight years later Cobbold described,' under the name of S. douglassii, a nematode which occurred in great numbers in the proventriculus of certain South African ostriches. Their presence was associated by the ostrich-farmers with a certain amount of disease, and with some deaths. Finally, we have the species S. quadriradiatus recently described by E. C. Stevenson. It occurred in considerable numbers in the intestines of a flock of fancy pigeons which had been almost destroyed by a malady of unknown origin early in 1904. In his article upon this disease, Stevenson points out that the presence of a few nematodes in the ceecum of the pigeon causes little harm. If, however, the threadworms exist in large numbers, disease becomes manifest. This Stevenson attributes to two causes : the first is the loss of blood ; but there is, I think, little or no evidence that these nematodes live on blood. The second cause is the piercing of the walls of the intestine," which permits the bacteria in the contents of the alimentary canal to make their way into the peritoneal cavity, where they set up peritonitis. Evidence is gradually accumulating as to the occurrence of this, and some of the French authorities even think that such a perforation, made as a rule by Trichocephalus trichiurus [dispar), is one of the more common, if not the most common, causes of appendicitis in man. The presence of these worms further sets up an inflamed, catarrhal condition of the walls of the intestine, which leads to a debilitating diarrhoea and to general disorders of the digestive system. As in other cases, the nematodes doubtless give off toxins, the effect of which is largely confined to the nervous system and to the cells in the blood of the host. The genus Trichostrongylus has recently been established by Looss ' to include certain forms which he has separated out from the large genus Strongxjlus. The Strongylus pergracilis of Cobbold corresponds so closely in structure with the species described by Looss that I think there can be no doubt that it also should be included in the new genus. The suggestion made above ' Journal of the Linnaan Society, London, " Zoology," xvi., p. 184, 1883. "An actual iieiforation of the membrane is not in all cases neces.sary. Tlieie are examples ofliacteria traversing tlie wall or parts of the wall of tbe alimentary canal which have been locallj' or temporarily wejikened in some way. " " Centralblatt fur Bakteriologie, Parasitenkuude," xxxix., ]>. 409, 1905. PLATE XXXIII. 3. Unsegniented egg. Egg with two blastomeirs. Egg with four blastomeies. Ej;g with eight lilastomeies, oiilj' six showing. Egg with lilastonieres, all showing. Egg with sixteen lilastonieres. Egg with thirty-two hlasto- ineres. Egg with sixty-fonr hlastomeres. Egg with eoiled- up larva, lipe for hateliing. A similar egg, artificially rnptiired, and the larva in the act of escaping. This shows the contraction of the egg-shell when niptnrej. Fig. 1. Male Trkho- slmrtgyhis pi rgrocilis, sliowing vt month, ali- mentary canal, sj»ie»iles, and geiMtal Imrsa. Magnitied. Firj. 2. Eeniale T. per- gracilis, sliowing on. anus : r (j/. cephalic glands ; m. month ; oc. lescipliagus; (;/'. ove- jeet"r; o. ovary; j}li. pharjnx ; r. rectum ; !(/. uterus with aegincnt- ing eggs; n. vagina. Magnified. Fii;. 5. A female 7'ri-hosoiifi loiijicolle. Magnitied about seven times. I'lo. 4. Three specimens of female Triclwsoma longieotlc. Magnitied about twice. TniCIIOfiTliONGYLUS I'EIKiliACILIS AND TlilCIIOSOMA LONGICOLLE. Oiiposilr ;>. 200.1 " GROUSE DISEASE "—STRONGYLOSIS 20^ that Strongylus tennis Eberth of the goose should also be reckoned as a species of Trichostrongylus was made to me by Dr R. T. Leiper. Specimens of T. pergracilis are found in the caeca of most Grouse. They are apt to cover themselves with mucus and dirt, and are consequently hard to see and often overlooked. We have found them, with hardly an exception, in every one of the two thousand Grouse examined.^ They are rendered opaque and white, and hence much more apparent, by shaking up the contents of the csecum in 75 per cent, alcohol, to which a few drops of corrosive sublimate have been added. Their presence is also readily detected by compressing a drop or two of the caecal contents between two microscope-slides and holding them up to the light. The worms, if there be any, then appear as thin, white, transparent lines. We owe this method to Dr Wilson. T. pergracilis is an extremely fine worm, measuring in the male on the average 6 to 8 mm., and in the female 8 to 10 mm. They are very narrow and hair-like, and, as a rule, whitish in colour, but sometimes have the tinge of blood when seen in a very thin layer on a slide through the microscope. They are very transparent, readily revealing their internal structure, and they are so soft that the pressure of a cover-slip almost always ruptures them. The cuticle is very clearly and definitely ringed, and the rings are so constituted that whilst the worm can easily work its way forward through a tissue, it would have diflficulty in wriggling backward. The rings give the edge of the body a strongly serrated appearance like a saw. This is most marked a little way behind the head, and extends over about one-third the body length. There is no trace of longitudinal marking on the cuticle {vide PI. xxxiii., Figs. 1 and 2). The genital bursa or expansion at the tail of the male is well formed, and opens by an oval opening with its long axis longitudinal. The bursa is supported by a number of ridges as an umbrella is by its ribs, and, using Looss's nomenclature, these are arranged in three groups. The members of each group arise from a common root and are recognisable, even when, as in the case of T. pergracilis, some of them run close to and parallel with members of another group. The three groups are: (1) Dorsal; (2) Lateral ; (3) Ventral. The spicules in the male are very conspicuous and very difificult to describe. They are short, strongly chitinised, with thickened edges and a kind of haft or base at the anterior end ; and each spicule is hollowed something like a crumpled, withered, lanceolate leaf. Each spicule is provided with retractor and protractor muscles, ' Vide vol. ii. Appendix D. VOL. I. 0 '210 THE GROUSE IN HEALTH AND IN DISEASE and when protracted they are divaricated. When in this extruded condition they form a cross, the left spicule projecting to the right and vice versa. Besides the spicules and between them, rather to the posterior end, lies the accessory or median piece, which Looss calls the " guberuaculum." It is best seen in profile, and has then somewhat the outline of a Turkish slipper. It also has muscles inserted into its ends. Near the base of each spicule is an oval clear vesicle ; but apparently the end of the spicule was outside and not inside the lumen of the vesicle. The head presents very little signs of differentiation. In some specimens with a one-twelfth objective three very minute lobes can be seen, but they are not visible in all cases, and their appearance may be due to some expansion of the mouth. The mouth is terminal and leads into a slightly bulb-like cavity which soon narrows into the thin capillary lumen of the alimentary canal. The oesophagus is more granular than the intestine, and separated from it by a very shallow groove ; its walls consist of flatly rounded cells with conspicuous nuclei. I could not detect any parts in the intestine ; it appears to be an undifferentiated tube running from mouth to anus, the lumen lined with chitin and the walls formed of granular cells with visible nuclei. No food was seen in the alimentary canal. Posteriorly the intestine widens into a spacious rectum, which just in front of the anus narrows again into a short, thin, terminal portion. The anus in the male opens into the genital bursa ; in the female it is a little distance in front of the end of the pointed tail, but relatively not so far forward as it is in the larva. Two cervical glands run about a fifth of the length of the body backwards, and end with rounded ends about the same level. In the male the testis begins about the level where these glands end. It consists of a single tube, the cells lining which give rise to the spermatozoa. Anteriorly the cells when squeezed out seem amoeboid, with rounded and very refringent nuclei. The hinder end of the testis is, however, crowded with spermatozoa shaped like little squat bottles, and in some specimens the genital bursa sheltered two clumps of these, looking as though they had escaped from the two vesiculse seminales. I saw nothing of excretory canals or their opening, and unless an ill-defined ring which surrounded the alimentary canal about one-twenty -fifth of the body- length from the anterior end be the nerve-ring, I saw nothing of the nervous system. The ovaries are double. Each tube arises about the level or a little behind the "GROUSE DISEASE "-STEONGYLOSIS 211 level of the hinder end of the cervical glands. One of them runs, with but slight undulations, straight to the "ovejector" which opens by the vagina, situated about one-sixth of the body-length from the hinder end, the other passes the vagina and reaches back almost to the anus ; it then doubles forward again and opens into the posterior "ovejector." The anterior end of each ovary contains undifferentiated protoplasm, but soon eggs begin to appear. At first these are very flattened, like a pile of coins, much broader than they are long ; then they become thicker, and, finally, three or four times longer than they are broad. The rounded nucleus is in every stage very conspicuous. It is impossible to say precisely where the ovary ceases and the oviduct begins. We find the long cylindrical cells rounding themselves off", and an egg shell beginning to appear. By this time fertilisation must have taken place, but I have not seen any spermatozoa in the oviduct. The oval cells usually lie at first with their long axis at right angles to the longitudinal axis of the oviduct ; then, when a little older, they lie obliquely, and, finally, they come to lie with their long axis parallel to that of the duct, in which position they are most readily swallowed by the "ovejector." The anterior and the posterior oviducts usually contain one, two, or three unsegmented ova ; then come some six to eight segmented eggs repre- senting as a rule the stages with two, four, eight, sixteen, thirty-two, sixty-four, and sometimes a hundred and twenty-eight blastomeres. One or two of these stages may be represented by two ova, but in any case the segmentation must be very rapid {vide PL xxili.. Fig. 3). The lower end of the oviduct is lined by what, in optical section, appear to be high columnar cells with very granular disintegrating borders. These seem to be secreting something. The walls of the oviduct pass suddenly into the "ovejector," which consists of three parts : (a) The most internal is somewhat funnel or trumpet- shaped, its wider mouth is continuous with the walls of the oviduct and is crenellated ; the funnel is richly supplied with both longitudinal and circular fibres ; not infrequently it contains an egg. (6) The second chamber of the "ovejector" is spherical, very transparent, and is marked by the presence of a large number of radiating muscle-fibres running from the periphery to the limits of the lumen. The contraction of these fibres would enlarge the lumen and suck the egg on. (r) The third chamber of the " ovejector" is thin-walled, with a chitinous lining. It frequently shelters an egg. At its outer end it narrows, and uniting with the similar narrow end of its fellow it forms an extremely short vagina which opens to the exterior by a longitudinal slit, the edges of which are also crenellated {vide PI. xxxiii. Fig. 2). 212 THE GROUSE IN HEALTH AND IN DISEASE The ova are laid iu the Huid contents of the host's ceeca in which they are frequently found floating. We have found developing ova in the caeca of a young Grouse chick of seven to ten days of age from Auchentorlie, Dumbartonshire. Apparently the ciBca are the chief centres of absorption of the digested food ; they contain none of the cellulose skeletons of vegetable cells so common in the intestine, and none of the masses of cast epithelium which make up so large a proportion of the flocculent masses in the duodenum. The eggs may develop further inside the csecum, though as yet we have not found an egg containing an embrj^o in its contents. A small pellet of the cascal contents, such as can be carried away on the point of a needle spread out under a cover-slip, will, in a well infected bird, show some twelve to twenty worms and one hundred to two hundred eggs in the field of a two-thirds inch Ross's objective with a No. 2 eyepiece. Allied I'^ ^^^ Memoir on the genus Trichostrongylus, Looss enumerates species. ^]^g following four species : — (1) T. EETORTJEFORMis (Zeder), 1800. From the duodenum and exceptionally from the stomach of i/ej>«s iM?wt/ws and Lepiis cunicuhis (when undomesticated). Railliet says it coexists with Strongylvs strigosus, and helps to give rise to a per- nicious anaemia. It develops directly without intermediate host. (2) T. /irar^^/i/^ (Railliet), 1893. Syn. T. suUilis Looss, 1905. From the duodenum and exceptionally from the stomach of Ovis aries, Oris laticauda, Antiloije dorcas, Camelus dromedarius (Egypt), Papio (Cyiiocephcdus) hama- dryas (North Africa), and occasionally in Man (Egypt and Japan). Railliet states that this species, together with Hcemonchus contortus, lives in the duodenum of sheep which succumb to pernicious anaemia. (3) T. PiJOJSOiC'ijra (Railliet), 1896. From the duodenum of Oris aries, Ovis laticauda, Antilope dorcas, and occasionally of Man (Egypt), and Camelus dromedarius (? Paris and Egypt). (4) T. riBRiNus Looss, 1905. From the duodenum of Ovis aries, Ovis laticauda, occasionally from Camelus dromedarixis and Man (Egypt). Looss regards this as a rare species. To these must be probably added : — (5) T. TEmjis {WoQxih), 1861. Syn. 5. ienuis (Mehlis) Eberth, 1861. From the caecum of the goose, Anser cinei'ea, and (6) T. NODULAius {'R\xA.),\m^. Syn. aS. nocZ2er^?'aci7i's in the caeca of nearly all sick adult Grouse, it became a matter of importance to study in some detail the life-history of this parasite with a view to determining the manner in which it is reproduced and disseminated, the mode of infection of healthy birds and, if possible, to obtain experimentally the symptoms of " Grouse Disease" under artificial conditions. In order also to have some reasonable basis of fact upon which to establish preventive and curative measures, a knowledge of the conditions favourable to and inimical to the growth of the parasite at its various stages of development became necessary. The present section deals with the results of an inquiry into these problems. The parasites are exceedingly fine hair-like worms of about one-third of an inch in length, and of a pale pink colour, but of such transparency as to be almost 1 See "Journal Tropical Medicine and Hygiene," x, p. 304, 1907. Filaria amithi cannot, however, stand as the name is preoccupied by Cobliold's species, Filaria smithii, from the elephant. Tranmctions of the Linnmtn Society of Londvii, 2nd. " GROUSE DISEASE "—STRONGYLOSIS 219 Fig. 16. Morulce of eggs. invisible to the naked eye. They live in the caecal portions only of the intestine of the Grouse. The sexually mature females give rise to •' ° Develop- their progeny as eggs, which undergo a certain degree of develop- ment ment while still within the body of the worm. By the time they are body of the laid the egg content has become subdivided into a large number of cells, forming what is technically known as the morula (Fig. 16). As morulce these eggs pass into and mix with the contents of the cajca, all further development thereupon ceasing. This suspen- sion of development appears to depend upon a lack of some necessary stimulant in the ceecal contents, for the eggs may be found alive and at the same stage not only several days, but even so long as a month after the death of the bird. In nature the cseca are evacuated periodically, and the ova thus pass out of the body with the soft portion of the bird's dropping. In one or two cases where a portion of the csecal contents had passed into the rectum, and had there become diluted somewhat by the fluid from the great intestine, eggs were found to have progressed to the formation of an embryo while within the body of a dead bird ; but such a condition is obviously abnormal, and does not invalidate the general conclusion that the eggs of this parasite require to pass out of the body of the bird before they are able to continue their growth, and that, in consequence, the parasites within the body cannot increase in number by sexual multiplication. Each and every parasite found within the body of the Grouse must therefore have actually entered it from the outside. We shall see later that this explains the apparent anomaly that whereas practically all Grouse are infected with Trichostrongi/lus only some suffer from the disease. The egg, when newly passed, measures 0"075 mm. by 0"046 mm. and contains a morula composed of about sixty-four cells. If a freshly passed csecal dropping be isolated and kept uncontaminated no further development will take place in the ova contained in it. A fundus will gradually grow upon it, and owing to this and bacterial con- oeveio tamination the eggs eventually die. If the dropping be exposed ™^"* °f *^® to the drying influence of sun and wind, as on the moors during ^^^ ^'^^y- summer, it becomes caked and dry, and the eggs die. If, on the other hand, csecal dropping be spread out in such a w^ay as to admit of the whole becoming 220 THE GKOUSE IN HEALTH AND IN DISEASE oxygenated by the atmosphere, and it be also slightly moistened, development will proceed, its rapidity increasing with the temperature. Cultural ^'^^ ^^^ experimental study of the extra-corporeal development the methods, following method was found most reliable. Petri dishes, as used in bacteriological research, of a diameter of about 4 inches, were employed in pairs. Into the upper dish was placed a closely fitting piece of thick blotting paper, which was thoroughly moistened with water. The inside of the lower dish was smeared uniformly with a very thin layer of csecal dropping or ceecal content taken direct from a dead bird. Several drops of water were then added and mixed into the viscid layer by means of a glass microscopical slide so as to produce a glairy mixture that would but slowly slide off the Petri dish when it was held almost upright. The layer of fceces should be sufficiently thin to allow of an examination under the microscope with a two-thirds inch lens. The upper Petri dish was then placed over the lower dish, forming a close chamber, the atmosphere of which quickly became saturated with water vapour. From time to time the Petri dish was opened and a small quantity of fseces removed on a platinum wire for microscopical examination, or the lower part was placed upon the stage of the microscope and directly observed. A similar method, and one which permitted the study of the various stages of development in a small number of eggs, was the use of hanging drop dishes. If the former of these two methods has been adopted, in the course of twelve hours the colour of the culture in the Petri dishes should have changed from a greenish yellow to a reddish brown, and a sickly sweetish odour, similar to that found in lactic acid fermentation, should have become distinctly appreciable. Otherwise experience teaches that putrefactive processes will almost certainly set in and lead to the destruction of the eggs and worms in the culture. After the eggs have hatched, and when minute worms are seen wriggling through the culture, it will be found advantageous to leave the Petri dish open for several hours in order to allow of the evaporation of some of the water, and the culture to acquire more consistency. A larger amount of water appears to be necessary for the growth of the young parasite previous to hatching than afterwards. Indeed we shall see later that a certain amount of consistence appears to be absolutely necessary for the full growth of the young worm. In the culture made by the above method the egg mass continues rapidly GROUSE DISEASE"— STRONGYLOSIS 221 to segment until the resulting cells are exceedingly small. The mass becomes somewhat flattened, and a slight dimple appears at one border of Deveiop- the oval disc (Fig. 17). This is the first step towards the formation "han^fes in of the cylindrical body of the young embryo. By the gradual deepen °'^""'"- ing of this dimple the egg mass acquires a tadpole - like appearance, the anterior end being, thus early, easily distinguished from the posterior end of the body. The anterior portion soon exhibits a central depression, which indicates the commencing for- mation of the mouth (Fig. 18). As the lateral dimple continues to deepen the body mass elongates to such an extent as to become folded upon this two or three times, in order to become accommodated within the shell (Fig. 19). The alimentary canal meanwhile has gradually been developing, so that by thetimethe embryo attains a cylindrical form the canal is found to extend throughout the body as a distinct cell-walled tube (Figs. 20, 21). During the whole of this period the embryo remains quiescent, but about an hour or so before it leaves the egg-shell it commences to exhibit a certain amount of movement. This movement gradually increases Fig. 17. Fig. 18. Developing ova of T. pergracilis. Fig. 19. Fig. 20. Formation of the larva of T. pergracilis. Fig. 21. in extent and vigour, until it ultimately overtaxes the resistance of the egg shell, which suddenly ruptures. The success or failure of these eff"orts on the 222 THE riROUSE IN HEALTH AND IN DISEASE part of the young worm appears to depend on the amount of water which is imbibed from the outside, for if only such an amount of water be added to the culture as is absolutely necessary to set the process of development in motion, and the culture be then allowed to dry somewhat, it will be found that the embryo is incapable of rupturing the egg shell. A slight collapse of the egg shell, owing to an insufficiency of water, causes the death of the embryo at any period of its growth. Hatching usually takes place in from thirty-six to forty- eight hours after the egg passes out of the bird ; but in summer it may be delayed for even as long as a month. When the embryo is hatched there seems little purpose in its early movements. The cuticle, at first irregularly crinkled, gradually smoothens as the parasite becomes saturated with water. The movements now appear to gain in purpose, and very soon the little worm is actively moving about, obviously in search of food. When newly hatched, the embryo measures 0'36 mm. in length, and 0'015 mm. in greatest thickness (Fig. 22). The cuticle shows no regular striation. The body Anatomi- i'"^ Cylindrical, tapering to a slender pointed tail in the last O'l of a acters'o^f ™™- of its length. Anteriorly it maintains an almost uniform diameter theembiyo. ^^ within 0"05 of the mouth, when it shows a slight and gradual narrow- ing. The anterior extremity ends bluntly, and has a diameter of 0 "007 5 mm., presenting at its summit the small rounded opening of the mouth capsule. At 0'06 mm. from the tail the anal pore opens with but little external indication. Alimentary Canal. — Two faint parallel lines are seen running inwards for a distance of O'Ol mm. from the oral pore. These are the walls of a cylindrical mouth capsule, which later, with the growth of the worm, become much more thickened and obvious. The oesophagus measures 0"1 mm. in total length, and is divided into two portions. The anterior two-thirds is cigar-shaped, uniting by a narrow neck with the posterior one-sixth which becomes bulbous. Surrounding this narrow neck are a number of large refractile cells, forming the nerve ring of the central nervous system. The oesophageal portion of the gut discharges into a long chyle intestine. The epithelial cells of its wall lie at first almost in touch, and the lumen is visible merely as a long, fine, wavy streak passing along the centre of the body. The rectum is short, 0"01 mm. in length, and is cuticular. Upon the success of the embryo in obtaining a plentiful supply of food depends almost wholly its future growth. If a freshly hatched embryo be " GROUSE DISEASE "— STEONGYLOSIS 223 Figs. 22 and 23. Xewly hatched embryos of T. pergracilis, highly magnified. 224 THE GROUSE IN HEALTH AND IN DISEASE transferred to plain water it will live for several days, but show no growth or further development. Evidently there is only a sufficiency of reserve sub- stance within the ovum to develop the embryo to the time of hatching. When there is enough food, but the medium is very aqueous, the worm requires to exert itself to a much greater extent in order to entrap small solid The first .,„„,...., ^ moult or particles or food into its rigid and chitinous mouth capsule. If, Gcdvsis. however, the culture is of such consistency that the embryo is able, by burrowing its way through the faecal matter, to force this into its mouth capsule, there follows a very rapid growth in size and early differentiation of tissue, even when there is a marked lack of oxygen. Under these favourable conditions of food supply an embryo increases in size to such an extent that on the fourth or fifth day from the commencement of the culture it is obliged to shed its cuticular covering. At this time thousands of very delicate sheaths may be found floating in the culture for a few hours ; Ijut they very rapidly disappear. The embryo now measures about 0"46 mm. in length, the oesophagus 0'12 mm., the anus line 0'08 mm. from the tip of the tail (Fig, 23). An excretory 2wre is to be seen 0'09 mm. from the anterior end of the body, and at 0"24 mm. from the anterior end there is now visible a small clear globule 0*005 mm. in diameter lying on the ventral surface between the body wall and the wall of the chyle intestine. This is the rudiment of the future genital system. A marked difference is now noticeable in the chyle intestine. Three large well - developed valves are seen governing the entrance to it from the oesophagus. Its lumen is widely dilated, 0*01 mm. in diameter, and is filled with ingested faeces. The cells of the gut wall are flattened and very finely granular. No gross structural alterations accompany this first moult or ecdysis, but during the succeeding three or four days certain changes within the body of the worm gradually become evident. The cylindrical mouth capsule (Fig. 24) slowly loses its clear cut border and appears to be undergoing absorption, and its lumen decreases (Fig. 25). At Themeta- ^^^ samc time the oesophagus lengthens, the bulbous posterior portion morphosis. becomes pyriform, and later merges into the anterior portion, but so gradually as to be only definable with difficulty. The cuticular lining of the whole oesophagus, and the marked triradiate lining of the oesophageal bulb (Fig. 24) become resolved into a simple thin cuticular covering (Figs. 25, 26). The walls of the intestine, which have gradually increased in size, become more "GROUSE DISEASE"— STRONGYLOSIS 225 clearly defined, and now appear as cylindrical turgid cells distended with large globules of highly refractile substance, giving the larva a characteristic appear- ance by which it can be readily distinguished from free-living nematodes (Fig. 26). The whole body appears to have slightly narrowed during the process of metamorphosis, by the conclusion of which the larva has become changed into a slender actively moving worm, with a simple elongated tesophagus without mouth capsule (Figs. 26, 28). Accompanying the metamorphosis in structure is a marked change in habits, for instead of burrowing into the denser portions of the food Fig. 24. Fig. 25. Fig. 26. Changes in T. pergracilis during ecdysis and encystment. Fig. 27. these metamorphosed forms now rush about with great rapidity, and either wriggle into the patches of open water or make their way on to the actual surface of the culture, and may be seen standing out in numbers into the moist atmosphere above, forming a kind of hoar frost on the surface of the faeces apparently in search of oxygen. Those larvse, which are fortunate enough to be near the edge of the culture, ascend in the condensed water on the sides of the Petri dish and make their way on to the upper part, eventually reaching the blotting paper. VOL. I. P 226 THE GROUSE IN HEALTH AND IN DISEASE Others will crawl out of the thin edge of the culture medium and become stranded on the dry glass. This metamorphosis takes place between the eighth and sixteenth day from the commencement of the culture, the difference in time depending almost entirely on the temperature at which the culture is kept. If the blotting paper be now removed, and the upper part of the Petri dish be put aside, so that the moisture on its inner surface, which contains The second *^^ actively Wriggling metamorphosed larvae, be allowed to evaporate '^eiioyrt- slowly, it will be noticed that as the water disappears the move- ment." ments of the larvas gradually diminish and eventually entirely cease, so that ultimately the larvae lie sometimes making irregular figures like notes of interrogation, sometimes coiled up like a watch spring (Fig. 29). If drying proceeds sufficiently slowly it would be found on examining the dish with a band lens, that when all traces of moisture have disappeared the little coiled larvae stand out as turgid, glistening streaks. They seem to be capable in this condition of retaining a certain amount of moisture within their thick resistant cuticle for several days, and to make up for any loss of fluid by evaporation by slowly retracting the body from either end and of detaching themselves from their cuticular skin (Figs. 26, 27, 30). This retraction may go on to such an extent that if one suddenly adds water once more to a Petri dish containing such dried forms the little worms are found enclosed in long sheaths that extend much beyond each end, recalling the sheathed embryos of filaria seen occasionally in the blood of man. This second formation of a sheath, or as it is sometimes called, the " encystment," is the last stage of the development of the larvae outside the body (Fig. 30). It appears to be a necessary preliminary to the attainment of infectivity, and once this stage is reached the larvae can remain alive without food or further growth for weeks. The larva does not shed this second sheath until it reaches the alimentary canal of the Grouse. There are thus two moults in the extra-corporeal development. The first is completed prior to metamorphosis ; the second, subsequent thereto, is not completed during the non-parasitic period. So much then for artificial experiments. The following details of an experiment made during August 1909 serve to illustrate what actually becomes of the hatched worms under Larval ... migrations natural Conditions upon the moors. A culture made in the manner on heather, i ., , , n -n i r i t) r described above was taken to a small village, on the coast oi the Jiay oi Cardigan, where no Grouse lived or had been known to exist for many years. " GROUSE DISEASE "—STRONGYLOSIS 227 Some young plants of bell heather were sought, and eventually two or three small suitable plants were detached uninjured from crevices in rocks. These were planted in a Petri dish, and the dish was half filled with water so as to cover the roots. The plants were then set aside. A week later they were found to have survived the transplantation, and to have commenced to grow Fig. 28. Fig. 29. Larvte forms of T. pergracilis Fig. 30. Encysted larvse of T. pergracilis. under the new conditions. As the weather was showery the plants and dishes were left out in the open, and for two or three days in succession the raindrops hanging from the tips of the heather were microscopically examined. They were found to be almost free of life. On one occasion, however, a small free living nematode was found. Although slightly resembling the larvae of Trichostrongylus pergracilis it was readily dis- tinguished from them by its microscopical characters. 228 THE GROUSE IN HEALTH AND IN DISEASE Immediately after one of these periodical examinations, the culture of Trichostrongylus pergracilis, in which the majority of the larvae had just under- gone metamorphosis, was poured into the water round the roots of one of the experimental plants. The plant was left out in a typical " Scotch mist " for a couple of hours. At the end of that time raindrops were again taken from the highest tips of the heather, which were about 3 J inches above the surface of the water, and they were found to be literally swarming with the actively wriggling metamorphosed larvse of Trichostrongylus pergracilis. These larvae had ascended the wet stems and leaves of heather against the current of water that was trickling down towards the roots. Their intense activity was doubtless due to the large amount of oxygen present in the fresh rain. The plant was then taken from the Petri dish and placed in a cardboard box, which was sealed down. A month later the box was opened. The heather was found to be alive still and growing, but very dry. The tips of the shoots from which the raindrops had been taken were cut off and soaked in little watch glasses of fresh water, and in the course of half an hour there wriggled out from the crevices of the leaves of the heather a considerable number of larvae, showing at either end the long collapsed parts of the sheath which as we have already seen are characteristic of the larvae that have undergone drying under artificial conditions. The intestine showed the characteristic refractile appearance already noted. The following synopsis of the life-history of this parasite may be of interest Synopsis as Summarising the order and minimal duration of the various stages history. m the lite-cycle. April 1. Egg in morula stage passes out of Grouse. ,, 3. Larva hatches out and lives in dropping or in moist earth. ,, 5. First moult or ecdysis. ,, 8. Metamorphosis, larva now in actively migrating form. ,, 9 (or after). Larva ascends to tips of heather; if there is no mist, rain, or dew the ascent will be postponed. ,, 10 (or after). Encystment or drying; this represents the first stage of the second moult — an indefinite interval may intervene^ here. ,, 10. Larva swallowed by Grouse, and completes second moult. 11. Reaches cerg7-acilis and of centrifugalised wash- ings of heather from the moors to healthy uninfected Grouse had . . •' Experi- given uniformly negative results. From the observations described mental c -1 iuductioQ above the explanation of these failures becomes very evident. The of THcho- J 1 <• 1 • • 1 stronqylosis. eggs and embryos or the parasite require to undergo certain essential developmental changes for a period of almost a fortnight's duration before they acquire the power of infection when swallowed by Grouse. The forms got from the heather were undoubtedly non - parasitic nematodes and their young, for these bear a general resemblance to the unmetamorphosed embryos of Trichostrongylus pergracilis — many of them having a very similar type of mouth capsule. Moreover, the embryos of Trichostj'ongylus pergracilis do not acquire their migratory habit until they have become metamorphosed, and there- fore do not ascend the heather until they have entirely lost their oral ca^DSule. Until the above described experiments were successfully concluded the characters of the metamorphosed larvae were quite unknown, and therefore it was impossible that they should have been recognised in washings of heather. Owing to the fact that the deliberate administration of Grouse ffeces to healthy Grouse for the purpose of scientific observation is considered to be a form of vivisection (accidental infection occurs continually on the moors), and owing to the desirability that the various experiments of this character should be carried out by one member only of the Committee, the cultures were handed over to Dr Wilson for the purpose of administration to hand-reared Grouse at the Frimley experimental station. 230 THE GROUSE IN HEALTH AND IN DISEASE On June 19th, 1909, the culture which had just undergone metamorphosis, and which was therefore in the active migrating stage, was administered to an adult male bird one year old. The droppings of this bird were entirely- free from Trichostrongylus ova when the experiment was begun. An examination of the ffeces on the successive days showed that no infection had taken place. By June 26th the culture had undergone further development changes, and showed a large number of encysted forms. A dose was again administered by Dr Wilson, and some four days later ova of Trichostrongylus pergracilis were found in the droppings. The number of ova increased on successive days. On July 3rd a further dose of the same culture, now thirty days old, was adminis- tered. The bird died five days later, showing distinct loss in weight, the presence of a large quantity of chalky fluid in the rectum, and the caecal contents red with blood. From the j^ost-mortem examination I came to the conclusion that the bird had been killed by the passage of some of the last culture into the lungs, for there was considerable pneumonia, and quantities of the culture were found in the fine tubules. This first experiment was therefore not wholly conclusive as regards the actual induction of Trichostrongylosis by the administration of encysted metamorphosed Trichostrongylus jfer-gracilis larvae. It served to establish, however, that these larvte can reach the casca of the Grouse, attain their adult condition, and become sexually productive in the very short space of four days. It also demonstrated that the sudden invasion of the cfeca by a large number of Ti-iehostrotigylns jyergracilis produced such a marked eff'ect upon the mucous membrane as to fill the cpeca with blood. In the second experiment made by Dr Wilson ray culture was much older, and contained encysted forms. The doses were repeated periodically, with the result that in the course of two and a half months the bird fell in weight from 17 ounces to llf ounces. The ctecal droppings were as full of Trichostrongylus pergracilis ova as those of a bird suffering from Tricho- strongylosis, and the bird itself showed a similar condition of progressive weak- ness and emaciation. The mucous membrane of the caeca was covered wdth Trichostrongylus pergracilis, but no evidence of extravasation of blood into the lumen of the caeca was found on the death of the bird. Apparently that seen in the first case must have been associated in some way with the development of the parasite before reaching maturity. These two experiments indicated in so far as such a limited number may, "GROUSE DISEASE "—STRONGYLOSIS 231 that this parasite in very large numbers has a marked pathogenic action upon Grouse, inducing loss of weight, progressive wasting, and in extreme cases, death. An examination of serial sections of the cfeca in heavily infected Grouse shows that here and there the mucous membrane is penetrated by the anterior end of the worm ; but no evidence was obtained from the sections that such penetration led to the local invasion of the tissues by intestinal bacteria. The presence of eosinoplulia in the blood as demonstrated by Dr Fantham indicates that • 1 Signifi- certain substances secreted or excreted by the parasite pass into the oanceof circulation.' These, together with the loss of function of the cseca, owing to the extensive decortication of the epithelial lining by the worms, seem^ to me to sufficiently account for the resulting symptoms of the disease. The final invasion of the general circulation by bacteria represents the terminal phase in the progress of the disease, and not an essential factor in its causation. Most adult Grouse suffer also from a slight degree of Coccidiosis. This parasite to a much greater extent destroys the epithelial lining, so that were the common disease amongst Grouse primarily the result of invasion by intestinal bacteria, the coccidia should play a more important role than the Tricho- strongylus in the causation of the symptoms of " Grouse Disease." Yet it is well known that the droppings of adult birds may show evidence of considerable infection with coccidia without any symptoms of disease being apparent. Death of adults from Coccidiosis apparently only results from an intensity of infection not met with on the moors, but only in the hand-reared birds or birds experimentally infected. If it be accepted that Trichostrongylus jiergracilis is the primary and essential factor in the production of the common form of "Grouse Disease" Remedial remedial measures must be directed either to the destruction of the ™'^^s"'"'^s- adult parasite within the bodies of the birds, or of the young forms during their stay outside the body. The impracticability of the former of these two methods is obvious. The birds are unapproachable, and are spread over a very wide area. Vermifuges or antihelminthics are expensive and more or less poisonous substances, the dosage of which has to be carefully estimated and controlled. The problem therefore resolves itself into that of destroying the eggs and larvae of the parasites during their stay outside the body. The destruction of the eggs or embryos by surface dressing with cheap ' Vide chap. xiii. p. 316. 232 THE GROUSE IN HEALTH AND IN DISEASE chemical substances would appear at first sight to be a hopeful line of action, but the occurrence of the csecal droppings more or less all over the moor, and the enormous area requiring treatment, render any such methods futile. Moreover, as we have shown, the larvae after a brief period of development ascend the heather and can remain hidden in the crevices of the leaves, in a quiescent, invisible and living state for a prolonged period. The only conditions that could be inimical to these, the infective forms, would be atmospheric conditions Effect of °^ marked severity, possibly a prolonged frost or a prolonged drought, frost. Qj. destruction of the infected heather by fire or cutting. The eflect of extreme cold has been tested by subjecting the metamorphosed larvae to freezing in the cold storage rooms at the Albert Dock for a period of a week. On being thawed out of the solid block of ice it has been found that they quickly regained their activity. Exposure to slow drying, on the other hand, under experimental conditions, results in the death of the encysted larvae. Effects of Death from lack of moisture must be continually taking place on the drought, moors, although there may often be, even at the hottest parts of the day, an insensible transpiration from the growing plant, sufiicient to maintain the life of the larvae by preventing desiccation. Burning and cutting appear to be the only practical means by which infected heather plants can be properly purged. To one more or less unaccustomed to the moors it is a matter of astonish- ment to notice what might be described as the extraordinarily insanitary condition of the Grouse's home. Nearly every square yard of moorland shows traces of faecal deposits, and forcibly directs attention to the fact that there is an unnatural over-j^opulation of the moors. When one remembers that practically all Grouse are infected with Trichostrongylus pe7■5'rac^7^s, and that from every dropping thousands of Beiationof potential parasites normally emerge, it becomes evident that the In°d Trii^ro?^ greater the number of birds upon a given area, the greater in turn strongylosis, jj^yg);, \^q i\^Q infecting Capacity of the moor. But on most moors only a very small proportion of the heather is suitable for food for Grouse at certain times of the year,^ and as the Grouse is a very heavy feeder it follows that the parts of the moor from which the food supply is derived are just those likely to be the most heavily contaminated with droppings. The number of birds on a moor should be correlated, not with the size of the moor but with the extent of the suitable food area thereon. The amount ' Vide chap. iv. p. 71. "GROUSE DISEASE"— STRONGYLOSIS 233 of stock on a large moor may seem very low proportionately to the whole area, but when estimated in proportion to the food area it may prove exceptionally high, and this means a high potential capacity for the pro- duction of Trichostrongylosis, whilst the entrance of a few bacteria or protozoan parasites into the body may suffice to cause serious diseases owing to the rapid multiplication of the original germs. In helminthic infections, as we have shown, the parasite cannot multiply inside the bird. Birds with few worms remain healthy. The progress of the disease is correlated with the actual number of parasites entering and surviving in the body. The more heavily infected the food, the more heavily infected does the bird become. The following facts connected with the growth of the parasite outside the body of the Grouse emerged from our Inquiry, viz. : (1) that moisture is necessary for the development of the egg ; (2) that a minimal tempera- ture of several degrees above freezing point is essential not only for facts ^ • f ^ established. the development of the egg, but also for the metamorphosis or the embryo ; (3) that the embryo ascends the heather only after metamorphosis. These facts aflford us some explanation of the disease being a fatal one in the spring months. During the summer months many of the Cfecal droppings must be dried by the sun and wind shortly after they are passed, and the eggs thereby killed. The same agencies must also desiccate beyond revival a large number of the encysted larvfe upon the heather. During the winter months, however, this loss does not occur. Owing to the low temperature and continual wet the eggs remain in a living but quiescent condition. Even if an occasional spell of warmer weather occurs, and the eggs develop into embryos, it would be necessary that such period of high temperature should continue for at least a fortnight to enable these embryos to become converted into active migrating larvae. The result probably is that there accumulates upon the moors during the whole winter vast numbers of undeveloped eggs and unmetamorphosed embryos. The low temperature does not kill them, but merely suspends their growth for the time being. At the spring-time the minimal temperature rises gradually to such a point as to allow the continuous development of the eggs and embryos to and through metamorphosis, with the result that at this period there presumably ascends the heather the accumulated result of fsecal contamination during the winter months. The frequent rains and mists give the larvee ample opportunity to reach the topmost tips of the heather at this time. 234 THE GROUSE IN HEALTH AND IN DISEASE The rapid death of the eggs of Trichostrongylus pergracilis in fseces that have undergone temporary drying indicates that the drier the moor, the more T-c^ i ^ efficacious will wind and sun prove as natural antagonists to " Grouse Effects of '^ ° drainage, Disease." Again, as the infective forms of the parasite occur on the buruing, ■- ^ and "food" heather, it is evident that the greater the amount of "food" cutting. , , . . . heather in proportion to each bird, the less likely it is to become infected. As the periodical burning of heather increases eventually, not only the area of food heather, but at the same time destroys in the only effective way known the living parasites upon the area of heather burned, the policy of heather burning, advocated by other members of the Committee upon other grounds, receives additional support. The practicability and value of a periodical cutting of the heather requires further consideration by those acquainted with local conditions ; but, if practicable, such a measure should not only be a means of ridding large areas of the moor of infective material, and of bringing about a rapid increase in the "food" heather area, but might also be applicable to those parts of a moor and in those seasons of the year when burning is impossible. CHAPTER XI " GROUSE DISEASE " CONTINUED COCCIDIOSIS By Dr H. B. Fantham Part I. — The Morphology and Life History of Eimeria [Cogciuiuh) avium A Sporozoon causing a Fatal Disease among Young Grouse ^ I. Introduction. The subject of this memoir is a microscopic, protozoal parasite, which infests the lining epithelium of the alimentary canal of Grouse. It belongs to the Coccidia, a group of parasitic protozoa, many of which are known to occur in the digestive tracts of both vertebrates and invertebrates. These minute organisms reproduce by means of resistant spores, and belong to that class of the protozoa known as the Sporozoa. The Coccidia are of economic importance, inasmuch as they destroy the mucous membrane of the intestine of the host, thereby setting up enteritis which is accompanied by diarrhoea, and very often has a fatal eifect upon the unfortunate animal harbouring the parasites, especially if the host be young. Such a disease — termed Coccidiosis — has long been known in rabbits, and is often fatal. Occasionally Coccidiosis occurs in man. The life-history of a coccidian parasite is complicated. There are two phases in the life-cycle : — (1) 'i- multiplica- tive phase within the cells of the gut-epithelium of the host, and (2) a reproductive phase leading, after a sexual act, to the formation of resistant spores adapted for life outside the body of the host. The spores so formed are the means of spreading the parasite, and lead to the infection of fresh hosts. The two phases were formerly considered to belong to separate parasites ; but the occurrence of alternation of generations in the life-cycle of Coccidia was first suggested by R. Pfeiffer in 1892, conjugation was discovered in Coccidia by Schaudinn and Siedlecki (1897), and the complete life-cycle was demonstrated with a wealth of morphological and cytological ' Reprinted from the Proceedings of the Zoological Society of London, 1910. 235 236 THE GROUSE IN HEALTH AND IN DISEASE detail in the celebrated memoir of the late Dr Schaudinn (1900) on Eimeria {Coccidium) schubergi, parasitic in the gut of the centipede Lithohius forjicatus. Coccidia have been recorded from most of the gi-eat groups of the metazoa, but very few coccidian life-histories have been investigated completely. Dr Leiper, while working on helminthiasis in Grouse in May 1909, noticed the occurrence of coccidian cysts in large numbers in the gut of many Grouse chicks, with concomitant enteritis, very often proving fatal. The coccidian cysts are oval, and at first sight might easily be mistaken for eggs of worms. Dr Leiper suggested that Coccidiosis was a factor in " Grouse Disease," especially in young birds. Early in June 1909 I spent some time on one of Lord Lovat's moors in Scotland for the purpose of investigating Coccidiosis in Grouse chicks.' Previously we had noticed, at various times, the occurrence of Coccidian cysts in adult Grouse, but not in large numbers. I have much pleasure in expressing my thanks to Lord Lovat, Dr A. E. Shipley, Dr E. A. Wilson, Dr Hammond Smith, and Dr Leiper for aiding my researches by procuring material for me, and to Professor Nuttall, in whose laboratory much of my work was done. I also availed myself of the services of the Secretary of the Committee, who placed me in communication with a large body of correspondents through whom I obtained further material to enable me to continue the investigation, and to whom my thanks are tendered. In this paper I wish to record my researches on tlie morphology and life-history of Eimeria avium, more especially as it occurs in the Grouse. I would point out that the length of time at my disposal for these researches has been limited, only one season being available to me for procuring material, and I have had several other investigations to consider during the period, so that I was not able to give undivided attention to the elucidation of the protozoa of Grouse. However, the complete life-cycle of Eimeria avium, responsible for the dwindling of Grouse broods in spring, is here set forth for the first time, so far as I am aware. II. The Generic Names Eimeria A^^) Coccidium. Unfortunately, owing to the rule of priority, the generic name Coccidium (Leuckart, 1879) no longer holds, but is replaced by that oi Eimeria (A. Schneider, 1875). I am in sympathy with Professor Minchin, when he writes in a recent review : — " We regret to see the familiar generic name Coccidium replaced by Eimeria ; this is one of those many cases where, in our opinion, rebellion against ' The number of Grouse chicks dying of Coccidiosis on the moors is not easily estimated, for the chicks die in the lieather, and their tiny corpses are rarely found. "GROUSE DISEASE "—COCCIDIOSIS 237 the law of priority in nomenclature is not only lawful but imperative " {Nature, March 3rd, 1910). It would save much confusion if the question of zoological nomenclature were settled by an international committee/ as has been suggested by many able workers. The Coccidia of birds were first recorded in fowls by Silvestrini and Rivolta (1873), under the name Psorospermium avium. Subsequently Railliet and Lucet (1891) recorded Coccidia from fowls, naming the parasite Coccidium tenellum. I have followed Doflein (1909) in naming the Coccidia of birds Eimeria avium. The coccidian parasites were obtained from Grouse chicks, and I have succeeded in transmitting the Coccidia of Grouse to fowl chicks and to young pigeons. III. Methods. In this investigation of Coccidiosis both fresh and preserved materials were used. Samples of gut contents, taken from different regions, were examined fresh, and often these have been fixed wet with osmic or formalin vapour, and stained by Delafield's htematoxylin or by Giemsa's stain. Such smears were sometimes useful for examining merozoites. Oocysts, because of the chitinoid and almost impenetrable character of their walls, had to be examined fresh. For preserved material, the best fixatives were found to be Schaudinn's fluid (corrosive-acetic-alcohol) and Bouin's fluid (picro-formol-acetic), to which a few drops of absolute alcohol were added. Schaudinn's fluid tends to shrink the tissues, while Bouin's fluid requires much washing out. Sections, 5^ to 6^ thick, were made of the duodenum and csecum of infected birds, these parts of the digestive tract being esj^ecially examined. The chief stains used were Delafield's heematoxylin (either alone or counterstained with orange G or eosin), which was found to be most useful, safranin and lichtgriin, iron-hasmatoxylin (with or without Van Gieson's picro-fuchsin), and paracarmine. On the whole the heematoxylins proved of most service. On diluting some of the csecal contents or faeces of a Grouse chick suSiering from Coccidiosis, and examining the preparation microscopically, numerous oval cysts are seen (PL xxxvii., Figs. 61-66). Sometimes the cysts are also Morpho- seen in the small intestine just beyond the duodenum. These cysts may '°^y- have homogeneous contents, or, when older, may show four more or less well ' The subject of zoological nomenclature is now (1911) being so considered. 238 THE GROUSE IN HEALTH AND IN DISEASE differentiated sporocysts within them (Figs. 67-70). Each sporoeyst, if ingested by another Grouse, can develop two active, motile -germs or sporozoites (Figs. 71-76), which can penetrate the intestinal epithelium — especially of the duodenum — and so begin a new infection. Though the oocysts and spores are the most obvious external manifestation of Coccidiosis, it is usual, and certainly more convenient, to begin the life-cycle of the Coccidium with the minute sporozoite (PI. xxxiv., Fig. 2), the agent whex'eby primary infection is brought about. The sporozoites are minute, falciform, or vermicular bodies (PI. xxxiv., Fig. 2) capable of fairly rapid movement, and possessing great penetrative powers. They measure from 7u to lOu in length. The ends of the sporozoite are rather Young . 1 ■ 1- 1 1 growing pointed, the extremity that moves foremost being slightly more acuminate than the posterior end. The general body cytoplasm is more or less homo- geneous, exhibiting but very fine granulations. The nucleus has a definite rounded or oval contour. The chromatin is evenly distributed throughout the nucleus. When the sporozoites are liberated from the investing sporoeyst (PI. xxxvn.. Figs. 74-76), by the action of the pancreatic juice of the Grouse, they are capable of active movement. The usual method of progression resembles that of the sporozoite or motile trophozoite of a gregarine. The organism moves forward with a slow gliding movement, the forward progression being facilitated by the secretion of a viscid proteid substance that rapidly hardens. On the smooth surface thus pro- vided the coccidian sporozoite glides forward. The track of the sporozoite, as shown by its trail, can be stained, and the organism then shows the gelatinous or proteid material issuing from near the posterior region of its body (PI. xxxiv., Fig. 2). During the gliding movement waves travel down the body of the sporo- zoite, recalling what is seen on a larger scale in the billowy undulations of the foot of a snail. On other occasions a more rapid movement of the sporozoite occurs. The two ends of the organism become approximated and then rapidly straightened, the effect being to propel the organism forwards much more quickly than when the gliding movement alone is used. The sporozoite thus makes its way to an epithelial cell of the duodenum and proceeds to penetrate the cell. As it forces its way inwards (PI. xxxiv.. Figs. 3, 4), so the sporozoite curves on itself (Fig. 7) and becomes round and immobile (Figs. 5, 6, 8). The young, rounded parasite (Figs. 8-lU) is now on the trophic phase of existence, and continues to grow for some time, feeding passively on the food-materials of the host-cell. During this period the parasite is called a trophozoite (Figs. S-12a). PLATE XXXIV. '-■■e -^M-^ •^j -i/ji F" ■/*lW^ "■■■-I ■'■- ■ysT*''* ■ i«) I #1;: f. f^ ' 6.' 7. 'W &M' -^■^i ?'». II, ■^^*.^- 10. ■'«s^ 15. 16, i ■■■Pn ^■•^ r^ #: ■*»»«!,., ^^' ■f ( _m'^ -■ :^.- MB 17. H B Fantham del. 20, EIMERIA (COCCIDIUM) AVIUM. (Schizogony,) 22. E.WDson, Cambridge Opposite p. 238.] "GROUSE DISEASE"— COCCIDIOSIS 239 The nucleus of the trophozoite is approximately central in position, or sometimes to one side, and at first contains scattered granules of chromatin. It then becomes somewhat vesicular (Figs. 8-11), and gradually the chromatin collects into a central karyosome, lying within the nuclear sap (Fig. I2a). The position of the karyosome, however, is not always centrally fixed ; it may lie to one side of the nucleus (Figs, S, 10). The growth of the trophozoite naturally affects that of the host-cell. The protoplasm of the latter becomes more and more tenuous, great hypertrophy of the host-cell occurring. This condition is maintained for some time, and finally a limit is reached and atrophy sets in, the nucleus of the host-cell then appearing as a small, often crescentic mass (Figs. 10, 14) to one side of the film (Fig. 12) that represents the host-cell. A clear space often intervenes between the parasite and the enveloping epithelial film (Figs. 9, 11, 12). The trophozoite, having attained its full size (some 10/x to 12^ in diameter) within the host-cell, proceeds to divide, and the result of its division is to increase the number of parasites within the host. This stage in the existence of Eimeria aviuin is known as the schizont (agamont), and the method of multiplication is termed schizogony. The schizont (Fig. 12) is a more or less spherical parasite. At first it is uni- nucleate (Fig. 12a), but soon its nucleus begins to fragment (Fig. 126). The division of the nucleus of the schizont is of the nature of multiple fragmentation gchizo- rather than of a series of binary fissions of the nucleus and karyosome ^°°^'" (Figs. 13-18). The parasite is very small, and it is not easy to follow the cytological details, even under the best and highest powers of magnification. Some of the portions of chromatin in multiple fragmentation may sometimes appear connected by thin strands (Fig. 13) for a short period, but the fragments soon travel to the periphery of the schizont. The small daughter masses of chromatin, at first homogeneous, gradually show diflferentiation, becoming minutely vesicular with a dot of chromatin usually to one side (Figs. 14-16), but occasionally central. Thus the nuclei of the future merozoites are forming their karyosomes early. The daughter nuclei having migrated to the periphery of the mother cell (Fig. 16), the cytoplasm of the schizont concentrates around them, forming small ovoid masses (Figs. 18, 19). The daughter-forms so produced are the merozoites (agametes) which measure 6^ to 10/x in length. They gradually acquire a vermiform shape, and arrange themselves around the remains of the protoplasm of the mother 240 THE GROUSE IN HEALTH AND IN DISEASE cell like the segments of an orange or the staves of a barrel (PI. xxxiv., Figs. 20-22 ; PI. xxxv., Figs. 23, 24). Owing to this method of grouping, the merozoites are said to be arranged " en barillet." The groups, when ripe, soon break up, and the individual merozoites are liberated. The movements of the merozoites, w^hen free, resemble those of the sporozoites. The number of merozoites formed from a single schizont seems to vary. Eight to fourteen seem to be common numbers, but as many as twenty have been found. The merozoites finally are slightly curved vermicules (PI. xxxv., Figs. 23, 24), possessing a nucleus wJiich may be approximately central (PI. xxxiv.. Figs. 20, 21) or somewhat towards one end (PI. xxxiv.. Fig. 22 ; PI. xxxv., Fig. 23). The nucleus of the merozoite is small, and the presence of a karyosome is often not very evident, though there is a small granule of chromatin — representing the karyosome — usually to one side of the nucleus (Fig. 24). The ends of the merozoites are rather less pointed than those of the sporozoites, a feature that E. avium has in common with E. schubergi as described by Schaudinn. When the merozoites reach a new host-cell, they enter, become round, and proceed to grow as trophozoites in the same way as did their parent organism, and vxndergo later nuclear fragmentation in a similar manner. As the result of this, many more merozoites are produced, and as schizogony may be continued through several generations, the destruction of the gut-epithelium is very extensive (PI. XXXIV., Fig. 1). Towards the end of schizogony — especially in the csecum — relatively smaller schizonts with larger and fewer merozoites (Fig. 25), about five in number on the average, are produced. These larger merozoites appear to be formed near the end of infection, in company with large numbers of gametocytes, so far as evidence is available. These difi"erences in the schizonts might be taken by some investigators to be indicative of difierence in species — in other words, that more than one species of Coccidium may occur in the gut of Grouse. I do not state that this is not so, but personally prefer the view that the di3"erences in the schizonts and merozoites noted are refiexes of the condition of nutriment of the parasite. Wenyon (1907) has some interesting observations on the variations in the schizogony of E. falciformis in the mouse, and states that the variations are due to the nourish- ment available for the parasite. Again, the species found in the liver and gut of the rabbit (Coccidium oviforme and C. j^^^'Jorans) are now usually united into one species, Eimeria stiedce. PLATE XXXV. T^d*' ■:9 iairSaN • 23. 25. /(P ■ a - > . .si:; 29. ?./(*• 30. 24. ■ -tr'^-dl^'. 26. ..Xvfc V.-*^ , -or>. 27. 28 w' >.-- 31. 32. 1»J(^' ii%l 33. H B Fan'.ham del 34. 35. EIMERIA (COCCIDIUM) AVIUM. (Macrogamece formation.) 36. E .Wilson, Cambridge Opposite p. 24(1. J "GROUSE DISEASE"— COCCIDIOSIS 241 The merozoites originally produced in the duodenum pass lower down the gut and reach the caeca. At the ileo-caecal junction the epithelium is attacked again, and the merozoites rapidly grow to schizonts, which produce new generations of merozoites, so that the caeca soon contain very large numbers of the parasites. Probably Coccidiosis set up in the duodenal wall is sufficient to kill very young chicks, e.g., chicks eight to ten days old, while older chicks dying at the age of about four to six weeks may have partially recovered from duodenal Coccidiosis, but succumb to Coccidiosis in the caecum (typhlitic Coccidiosis). In cases of intense duodenal Coccidiosis, merozoites are found free in the intestinal contents, and even in freshly shed faeces. Sooner or later a limit is reached, both to the power of the Grouse chick to provide nourishment for the parasite, and to the multiplicative capacity of the parasite itself In other words, the host begins to react on the parasite. Consequent on the now unfavourable environment, the parasite proceeds to form gametes, in order that its species may be perpetuated. The gametocytes or mother cells of the gametes (PI. xxxv.. Figs. 26-28 ; PI. xxxvi., Fig. 37) are modified schizonts which are of slow growth, and therefore can accumulate more reserve food material in the form of granules within their cytoplasm. The processes leading to the formation of the gametes may be termed gametogony, which we may now consider. Sexual differentiation is characteristic of the gametes of Coccidia, and in the case of Eimeria avium the differentiation is apparent in the gametocyte phase. Two forms of gametocytes can be distinguished. The first group are intra- cellular parasites containing large granules of food reserve within their gonj'- cytoplasm. These are the macro-gametocytes (PI. xxxv., Fig. 26) which give rise each to one female gamete. On the other hand, the micro - gametocytes (PI. XXXVI., Fig. 37) or male progenitors contain a little reserve food material in the form of very minute granules, distributed evenly throughout the body substance. Each micro-gametocyte gives rise to many microgametes. The structure of the macro-gametocyte and of the single macrogamete that arises from it is very difficult to interpret in Eimeria avium, on account of the large amount of reserve food material contained within the cytoplasm. game°ocyte Further, it is very difficult to draw the exact dividing line between the gamete?'^" macro-gametocj'te and the female gamete, as the one gradually merges into the other. These forms vary from 11 "8^ to 17 '5^ in length by 6/x to 11^ in VOL. I. Q 242 THE GEOUSE IN HEALTH AND IN DISEASE breadth, as seen in sections. Many relatively large granules occur in the cytoplasm of the macro-gametocyte. As the macro-gam etocyte grows from round to ovoid, these granules gradually concentrate to form larger, roundish, haematoxylin-staining granules, which are albuminoid (PI. xxxv., Fig. 29), the chromatoid granules of many authors. There are also other, non-basic staining, granules known as plastinoid granules ("granules plastiques " of Thelohan and Labbe) composed of coccidin (Labbe). These ultimately are large and round (Figs. 30-32) and are refractile in fresh preparations, where they appear yellow or greyish-green. They tend to shrink in preparations fixed with sublimate or sublimate acetic (Fig. 29). The plastinoid granules occur between and among the chromatoid granules (Figs. 30-32). In stained preparations ^ the granules are best seen by staining with iron-hfematoxyliii followed by Van Gieson's picro-fuchsin, when the chromatoid granules appear blackish, while the plastinoid granules take on a uniform, yellowish hue. The plastinoid granules stain with lichtgrlln in marked contrast with the red of safranin taken up by the chromatoid granules. With Delafield's hsematoxylin, the chromatoid granules stain intensely (Figs. 29, 31, 32) and somewhat misleading appearances result, suggesting multiplication of the cell. As the parasite grows, the chromatoid and plastinoid granules travel towards the periphery (Figs. 29-32). The macro-gametocyte at this time encysts within the epithelium, and the chitinoid material of the cyst seems to be formed from the chromatoid granules. At any rate, the inner layer of the cyst-wall seems to take its origin therefrom (Figs. 34-36). The formation of the cyst-wall from the chromatoid granules has been noted by Simond (1897) and Wasielewski (1904) in the case of Coccidium oviforme {Eimeria stiedcB of Stiles). The formation of the cyst of Eimeria avivni takes place while the organism is still within the epithelium (Figs. 34, 35), and therefore the parasite encysts pre- cociously. Tlie macrogamete at this stage is ovoid, and the number of chromatoid granules within it is reduced. The cyst formed is ultimately rather thick-walled, but a small aperture or micropyle, which may be in a slight depression, is left for the entry of the microgamete (PI. xxxvi., Fig. 47). When Scliaudinn investigated the life-cycle of E. schuhergi, he described a process of maturation of the macro-gametocyte, whereby the karyosome of the nucleus was expelled in fragments. I regret that I am not at all sure as to the fate of the karyosome of the macro-gametocyte of E. avium. Several causes combine to defeat the attempts made to elucidate this subject. In the first place, ' The reactions of the gi-amiles are discussed by Labbr (189C) and by Mincliin (1903). PLATE XXXVI. \:. ■h---^A 37. "^ .jr. C 38. M '^'^ I, ->■; '.I 43. 42. 40. W' 39. '"7/- 45 V^ ^ 46, 44. (^:=- 48, 49 f 'Mf^ 53. H.B,Fanlham del EIMERIA (COCCIDIUM) AVIUM. (Microgametes, Sporogony.) 58. E VTilson, Cambridge Opposite p. 213.] "GROUSE DISEASE"— COCCIDIOSIS 243 the entire parasite {E. avium) is much smaller than E. schnbergi, and its karyosome is not nearly so well differentiated a structure. Further, the presence of the chromatoid granules, which stain deeply with basic stains, much confuses the structure. Similar causes prevail in E. oviforme {E. stiedce), as I can vouch from personal observation, and Wasielewski (1904, p. 54) states that he is unable to follow the maturation process in E. oviforme. It may be that E. avium is like some other Coccidia (e.g., C. lacazei C. proprium, Adelea ovata) where the karyosome is retained in the gamete and is left behind in the residual protoplasm of the oocyst. On a few occasions, I have observed a small chromatin-like granule in the oocyst residuum (PI. xxxvi., Fig. 57), and this body may be the karyosome of the macro-gametocyte. E. avium is distinguished by having a very small cystal residuum, which, together with the smallness of the karyosome, and indeed of the whole parasite, increases the difficulty of investiga- tion. However, at the time of fertilisation, the distinctness of the karyosome of the macrogamete has disappeared (PI. xxxv.. Figs. 29-36), and the nucleus of the macrogamete appears to contain granules of chromatin which are rather indistinct. The micro-gametocyte ^ (PI. xxxvi., Fig. 37) is an ovoid cell about 13/* long and Sfi. broad in the specimens that I have seen. It possesses a central nucleus contain- ing a karyosome. The process of the formation of the microgametes of E. avium is as follows : — The chromatin of the nucleus, laroely concen- ^^'^''°" ' & J gametocyte trated in the karyosome, breaks up (Figs. 38-40) into minute granules or '^^^ "uoro- •' r \ o I o gametes. chromidia which pass towards the surface of the cell, where they appear to form a very fine chromidial network (Fig. 38). The chromidia then collect into groups or patches, arranged in the form of minute, irregular loops with central hollows (Figs. 38, 39). These chromatic loops form a number of minute, fiexible, rod-like bodies, composed almost entirely of chromatin (Figs. 41-45). These are the young microgametes (Figs. 43-46). The adult microgametes are small parasites, their chromatic bodies measuring 3m to 4m in length, possessing a rod-like, some- what curved body composed of a core of chromatin, which is surrounded by a tenuous film of cytoplasm, prolonged outwards to form two fine flagella (Figs. 44, 46). The flagellum, which I term the posterior flagellum, trails behind the organism, and is practically a continuation of its body ; the other flagellum is at the opposite end of the body, and so is termed the anterior flagellum. In life, the microgametes are capable of serpentiform movements. Owing to the minute size 1 Uni - nucleate micro - gametocytes seemed rare in preparations, for the cell rapidly proceeds to form many microgametes. 244 THE GROUSE IN HEALTH AND IN DISEASE of the microgamete (about 3^ to 4^ long) it is only with the greatest diflficulty that the flagella can be discerned. The whole of the micro-gametocyte is not used in the formation of the micro- gametes. When separation of the microgametes from their mother cell occurs, a large amount of the body-substance of the latter remains as a somewhat faint staining residuum, in which the pale staining remains of the karyosome (Fig. 43, cf. Fig. 38) can sometimes be distinguished. The residuum takes no further part in the vital activities of the parasite. The microgametes are set free into the lumen of the gut, and proceed to seek out the macrogametes. When the macrogamete has attained its maximum development, it often lies in the epithelium, near the outer edge of the tissue, or may even burst through the Fertiiisa- attenuate wall of the host-cell and so reach the margin of the lumen of the *''°"' gut. The minute but active microgametes (PI. xxxvi., Fig. 46) mean- while have broken away from the residual protoplasm of the host-cell, and swum out with rapid lashing movements of their flagella into the gut. Here they are attracted, possibly by some chemiotactic substance, towards the macrogametes. The micro- gametes swarm round the micropyle of the macrogamete (PI. xxxvi., Fig. 47*) and several have been seen trying to enter it simultaneously. The nucleus of the macrogamete travels upwards nearei- the micropyle, and before long one microgamete effects an entry (Fig. 47 *), appears to bore its way into the female, reach the nucleus, and finally be lost to view. The macrogamete secretes a plug of protoplasm across the micropyle, whereby other microgametes are excluded, and the individuals thus shut out degenerate (Fig. 48). Such is the process of conjuga- tion as seen in the living organism, and the evidence of stained preparations is fully confirmatory of what has just been described. Owing to the presence of granules in the macrogamete it is extremely difficult to follow the subsequent stages of fertilisation. Occasionally there are indications of a fertilisation spindle (Figs. 50, 51), but the nature of the material frequently precluded observation of the same. The term "fertilisation spindle" is not exactly a happy one, for the object of that structure is the intimate interminefling of the chromatin of the uniting gametes. After the microgamete has reached the nucleus of the macrogamete, fusion. ' &et also PI. x.xxviil., Fig. 3, p. 252. 61. PLATE XXXVII. 62 /^. 63. 64. 65. 68. EIMERIA (COCCIDIUM) AVIUM. (Sporogon^) Opposite p. 215.] "GROUSE DISEASE "—COCCIDIOSIS 245 occurs and a zygote is produced. The contents of the zygote at first fill the oval oocyst (PI. XXXVI., Figs. 49-52), but gradually they shrink away from the poles. ^ The oiicyst itself may increase slightly in size during the con- centration of its contents, which ultimately form a globular mass, consisting of cytoplasm rich in fatty matters, within which is a nucleus, usually centrally placed. The nucleus (synkaryon) of the zygote proceeds to divide directly, first into two (Figs. 53, 56) and then into four (Fig. 54), the divisions following one another very rapidly. The granular protoplasm segments around the nuclei, and four sporoblasts (Fig. 57) are produced, each sporoblast separating from its neighbours as a small, rounded body (Figs. 55-57). Occasionally oocysts containing two ovoid masses of protoplasm (PI. xxxvii., Fig. 82) are seen, but as a rule the form containing four sporoblasts is the one found, the four sporoblasts being formed almost concurrently. The sporoblasts become ovoid (PI. xxxvi., Fig. 58 ; PI. xxxvii., Fig. 68), and each gradually secretes a tough, chitinoid sporocyst, usually differentiated as epispore and endospore, and so becomes a firm, resistant spore (PI. xxxvii.. Figs. 71-76). A minute amount of the cytoplasm of the zygote is not used in spore formation, but remains within the zygote as a small cystal residuum. The sporocysts continue within the oocysts for some time, during which period each sporocyst undergoes developmental changes, leading to the production of actively motile sporozoites. The contents of the spore at first are homogeneous (PI. xxxvii., Figs. 68-70), but gradually two refractile bodies or vacuoles appear at either end (Fig. 73), and the protoplasm gradually concentrates into two masses, just internal to each vacuole. The nucleus is at first central, but divides into two, and the halves migrate to the opposite poles of the sporocyst (PI. xxxvi., Fig. 58). The protoplasmic masses gradually displace the polar vesicles, so that the two vacuoles move towards the centre and coalesce (PI. xxxvii., Fig. 73), leaving nearly all the protoplasm of the sporocyst in two masses, one at each end (Fig. 71). Each of the protoplasmic masses gradually becomes vermiform, extending along one edge of the spore (Figs. 71, 72). Two vermiform sporozoites are thus formed (Figs. 72, 74), sometimes with their more rounded ends placed at opposite ends of the sporocyst (tete-heche) (Figs. 72, 74, 75), sometimes with the slightly swollen ends side by side (PL xxxvi., Fig. 59 ; PI. xxxvii., Fig. 76), the sporozoites being capable of movement within the spore just previous to their escape. There is a slight sporal residuum. ' In some cases the zygote-contents of the oocyst may be slightly nearer one pole than the other. 246 THE GROUSE IN HEALTH AND IN DISEASE The sporocysts when quite ripe tend to become more pointed at one end (PL XXXVI., Fig. 60; PI. xxxvii., Figs. 71 , 75, 76), where a slight thickening or small Stieda's plate (Fig. 71) may appear, which is a point of weakness, for here a rupture may occur under the action of the digestive juices of the fresh host, forming a sort of micropyle through which the sporozoites escape. Partially ruptured sjiorocysts are sometimes found (PI. xxxvi., Figs. 59, 60). In the case of Grouse chicks dying from acute Coccidiosis, ripe sporocysts have been found in the caecal walls themselves, as well as in the caecal contents, though usually mature sporocysts are found in csecal droppings that have been exposed. The oocysts of Eimeria airium show a fair amount of variation among them- selves. Usually the oocysts are oval (PI. xxxvii., Figs. 65-68, 71, 72, 77, 78), actually measured specimens varying from 25/u to 35m in length and from 14^ to 20/x in breadth. Sometimes the oocysts are not oval but subspherical (Fig. 70), and these are from 18m to 20yu in diameter. Somewhat pyriform or egg-shaped oocysts (Fig. 69) are intermediate in size between the oval and subspherical forms. Morse (1908) noted the occurrence of both round and oval oocysts when investi- gating white diarrhoea of fowls, in which Coccidiosis played an important part. Among the oocysts of E. avium certain were found with somewhat squarish ends (Fig. 78), while others had a slight depression at the apex (Fig. 79), but their development was identical with that of the more common forms. Occasionally, oocysts with two sporocysts only (Figs. 81, 82) were found, but these were abnormal forms, as was also a parasite (Fig. 83) in which the cytoplasm extended in a cone or funnel-like fashion to the edge of the oocyst. The size and shape of the oocysts are largely determined by the space in which the macrogamete develops and the amount of food available for the parasite. When there are many Eimeria present in any particular region of the gut, the oiicysts produced are relatively small, while where abundance of space and nourishment are available, the oocysts tend to be large. From experiments made by feeding birds with coccidian oocysts, I conclude that schizogony takes from four to five days. Uni-nucleate oiicysts mature their sporocysts in two to three days. The period for the total life-history of the parasite would be from eight to ten days. The larvae and imagines of Scatophaga stercoraria, the dung-fiy, ingest the oocysts of E. avium along with the Grouse faeces. The oocysts pass through the bodies of the larvae uninjured, and are scattered with the excrement, thus serving to disperse the spores to some extent. "GROUSE DISEASE"— COCCIDIOSIS 247 IV. Summary of the Life-History of Eimeria avium. The life-cycle of Eimeria avium is complicated, even though the organism completes its development within one host. The life-history may be represented diagrammatically as iu Text-Fig. 1, A-T (p. 248). Beginning as a sporozoite (PI. XXXIV., Fig. 2 ; Text-Fig. 1, A) liberated by the action of the pancreatic juice of the Grouse, the parasite rapidly penetrates an epithelial cell of the duodenum (Text-Fig. 1, B) and entering the cell rounds up (Text-Fig. 1, C) and becomes a passive growing trophozoite (PI. XXXIV., Figs. 3-7; Text-Fig. 1, D). After a period of rapid growth, during which time the trophozoite (Figs. 8-11) practically destroys the cell harbour- ing it, the parasite enters upon an asexual, multiplicative phase termed schizogony. The schizont is at first uni-nucleate (Fig. 12 ; Text-Fig. 1, D) but the nucleus soon fragments (Figs. 12, 13), the daughter nuclei migrate to the periphery (Figs. 14-16 ; Text-Fig. 1, E), cytoplasm segregates around each (Text-Fig. 1, F), and the daughter forms thus produced become meridionally arranged, like the segments of an orange, the arrangement of the merozoites being "en barillet" (PI. xxxiv., Figs. 17-22; PI. XXXV,, Figs. 23-25 ; Text-Fig. 1, G). Each merozoite is a small, vermicular organism, having a nucleus with a somewhat ill-defined karyosome usually to one side (Fig. 24). The groups of merozoites break up (Text-Fig. 1, H), and the free germs seek out and enter an hitherto uninfected cell where the parasite again assumes the trophic phase and then undergoes division as before. Several successive generations of schizonts and merozoites are thus pro- duced, resulting in a great destruction of the gut-epithelium of the host. Finally a limit is reached to the ability of the host to provide nourishment and to the multiplicative powers of the parasite, and this results in the onset of sexual differentiation. Gametogony may occur both in the duodenum and caecum. Certain schizonts become considerably modified in one of two directions. In the first case, food material accumulates, and a large, uni-nucleate food-laden form is produced (Figs. 26-30). This is the macro-gametocyte (Text-Fig. 1, I 9), destined to give rise to a single macrogamete (Text-Fig. 1, J ?). In the second instance (Text- Fig. 1, I etw^een the pla.<:tinoid gmn- ules. J. Micro-gametocyte with many bi-flagel- late microgametes about to separate from it. Karyosome left at the centre. Fertilisiition. One micro- gamete is penetrating the macrogamete, while other male cells arc near the micropylc but will be excluded. Fertilisation. The male pro- nucleus which entered through a micropylc is lying above the female chromatin. Degenerat- ing microgametes are shown outside the oocyst. . Oiicyst (encysted zygote) with protoplasmic contents tilling it completely. Nucleus with signs of fertilisation sjundle, , Oocyst with contents concentrated, forming a central spherical mass which has a vacuole in the middle and the nucleus to one side. Many such cysts seen in infected ca-cal droi»pings, P. Oticyst with four nuclei. Diagram of Life-cycle of Eiineria {Coccidium) avium. D-11 reprcvsent Scliizogony. 1-L, Gainetogoiiy. N-T, Sporogoiiy. Epithelial host-cells diagrammatical ly outlined. "GROUSE DISEASE "—COCCIDIOSIS 249 (PI. XXXVI., Figs. 47, 48 ; Text-Fig. 1, K ?). This oocyst-wall is formed while the parasite is within the epithelium. Fertilisation (Figs. 47, 48; Text-Fig. 1, L) occurs — the process has been watched in life — and the micropyle is then closed (Figs. 49-51 ; Text-Fig. 1, M). The fertilised oocyst (Text-Fig. 1, N) then passes into the lumen of the gut and is voided with the ffeces of the Grouse. The further development of the oocyst largely depends on climatic conditions. Under the influence of warmth and moisture, the contents of the oval oocyst (PI. xxxvi., Fig. 52; PI. xxxvii., Figs. 61, 62, 64) shrink away from the poles and become a rounded, central mass (Figs. 65, 77, 78 ; Text- Fig. 1, 0). The nucleus rapidly divides into two (PI. xxxvi.. Fig. 56) then four (Fig. 54 ; Text-Fig. 1, P) ; each nucleus has protoplasm segregated around it (PI. XXXVI., Fig. 55 ; PI. XXXVII., Figs. 67, 70 ; Text-Fig. 1, Q), a wall is secreted, and the net result is that four sporocysts (Figs. 58, 71-76 ; Text-Fig. 1, R) are produced within the oficyst. Within each sporocyst two sporozoites gradually differentiate (Figs. 58-60, 71-76; Text-Fig. 1, S), and when the sporocyst (Text-Fig. 1, T) is ingested by a new host, the sporozoites creep out of the sporocyst softened by the pancreatic juice of the new host and proceed to attack the epithelium of the gut, producing thereby the primary infection of the bird. The main differences between Eimeria avium (Silvestrini and Rivolta) and E. schnbergi (Schaudinn) may be briefly summarised : — (1.) E. avimn is smaller than E. schuhergi. (2.) The merozoites of E. avium are arranged "en bardlet," those of E. schuhergi "en rosace." (3.) Precocious encystment of E. avium occurs before fertilisation. This is not the case with E. schuhergi. (4.) Fertilisation in E. avium is micropylar; in E. schuhergi a cone of reception is formed by the macrogamete. (o.) The macrogamete of E. avium contains much more deeply staining reserve food-material than that of E. schuhergi, thereby increasing the difficulty of minute examination of the parasite. (G.) The cysts of E. avium are oval, those of E. schuhergi are round. V. The Effect of Eimeria avium on the Host. The effect of Coccidiosis on the Grouse may now be considered briefly, fuller details regarding the symptoms of the disease and its effects being given in the article relating to experimental Coccidiosis.^ 1 Vide Part II. p. 252. 250 THE GROUSE IN HEALTH AND IN DISEASE External Effects. — The chief external evidence of Coccidiosis is the pale colour and great fluidity of the csecal (soft) droppings of the Grouse, the pale tint being due to myriads of oocysts and the condition being that of diarrhoea. A similar disease in fowls is known among poultry-men as " white-diarrhoea." As the coccidian parasites cause great denudation of the intestinal epithelium, digestive derangements are brought about, and consequent on this, malnutrition occurs and the bird becomes very emaciated and " anfemic." Feathering also is poor and ragged, leg weakness is fairly common, and a peculiar bluish tint is sometimes seen at the cere, ears, and other parts. Eimeria avium appears to be purely a parasite of the gut of the Grouse and does not affect such gut diverticula as the liver. The crop and gizzard of infected birds are rarely parasitised, though they may contain oc'icysts in the internal condition in which they have been ingested with food. Examination of organs. •' ° the duodenum shows that the sporocysts ingested with the food are attacked by the pancreatic juice (as I have proved by pancreatic digestion ex- periments, using both natural pancreatic juice and trypsin), and the sporozoites are set free. These invade the tissue of the duodenum, rapidly become schizonts and multiply, the result being that the duodenum is often riddled by the parasites, and consequently inflamed. Both the villi and the crypts of Lieberkiihn are attacked, and the parasites have also been found, though much more rarely, in the submucosa. Great hypertrophy followed by atrophy of the epithelial host-cell occurs, and the tissue attacked is often reduced to a finely granular, structureless mass. Desqua- mation of the gut is common, and epithelium containing various developmental stages of the parasite can be found floating free in the gut contents. Some of the merozoites formed in the duodenum pass down the gut, reach the cseca and re-commence their life-cycle there. Active schizogony and sporogony go on in the cseca,' chiefly in the epithelium, very rarely in the submucosa. Often the cfeca are as heavily parasitised as the duodenum, whole areas being completely denuded of the epithelium, especially when the fertilised oocysts pass outwards into the csecal contents. The walls of the cseca are often rendered very thin and tender by the action, direct and indirect, of the parasite. Ripe oocysts and sporocysts occur in the lumen of the cseca of dying chicks. Podwyssozki (1890) stated that he found coccidian oocysts in the vitellus of eggs of fowls, especially in summer. He considered it possible that the cysts ' Coccidiosis may sometimes occur along the entire lengtli of tlie small intestine, and gametes may be formed far forward, in the duodenum. "GROUSE DISEASE "—COCCIDIOSIS 251 were derived from Coccidia in the oviduct of the mother, or perhaps from intestinal Coccidia which had ascended by way of the cloaca. I think that cloacal conta- mination was the more probable, for I have never seen Coccidia in the genitalia of adult (Irouse examined. A reflex of Coccidiosis is seen in the blood of infected birds, where polymor- phonuclear leucocytosis is induced (vide chapter xiii. p. 315). Lesions caused by Coccidia in the mucous membrane may admit bacteria to the circulation of the host (vide chapter xii. pp. 295 et seq.). Rettger (1909) believes that " white diarrhoea " of fowls in America is due to a bacterium, while Morse (1908) considers that it is primarily due to Coccidiosis. The discrepancy between the results of these American workers is thus capable of explanation. VI. Concluding Remarks. • Eimeria avium of Grouse is not restricted to this particular bird, for by administering f«ces containing oocysts from diseased Grouse to young fowl chicks and pigeons, I have been able to reproduce the disease exactly as it occurs in Grouse (p. 254). M'Fadyean (1891) found Coccidiosis in pheasants, while "white diarrhoea " of fowls has been the subject of much investigation, particularly recently in America, where Morse (1908) and Hadley (1909) have worked on the subject. Morse's account of preventive measures is very good, and he also notes Coccidiosis in many other birds, but the figures of the complete life-cycle of the parasite are not yet published. Labbe (1896) also has described Coccidiosis in certain marine birds. Though Coccidiosis is peculiarly fatal to Grouse chicks during the first few weeks of their lives, adult Grouse also can become infected, for I have examined an adult bird that probably died of Coccidiosis. Old birds in the chronic condition serve as reservoirs of oocysts and so may form sources of new infections on the moors. All infected corpses should be burned, not buried. I may add that, while correcting the proofs of this memoir, I have been able to examine pheasant chicks dying from Coccidiosis, the birds being obtained through the courtesy of Drs Shipley and Hammond Smith from various parts of England during June and July 1910. The economic importance of Coccidiosis in birds, especially in the young, is evident, and I trust that this work, which to the best of my belief is the first fully illustrated and detailed life-history of an Avian Coccidium, may draw more attention to a subject both of great scientific interest and of practical importance. 252 THE GROUSE IN HEALTH AND IN DISEASE Part II. — Experimental Studies on Avian Coccidiosis, especially in Relation to Yoong Grouse, Fowls, and Pigeons. I. Introduction. Protozoal parasites are highly specialised animalcules which live in intimate relation with the hosts they infect. While many of the protozoa are capable of living in one host only, there are others which are under suspicion of infectiilg several species of higher organisms as host, and of not being so limited to one host as was formerly believed. One test for the specificity of any protozoal parasite is that it fails to develop in any animal other than its special, natural host, and merely perishes when inoculated or otherwise introduced into any other animal. In order to test the specificity of the coccidian parasite of the Grouse, experiments were made, with the result that the Coccidium pathogenic to young Grouse and responsible for the dwindling of the broods, particularly in the spring and early summer, was found to be equally injurious to healthy young fowls and young pigeons. Healthy Grouse chicks also were experimentally treated by administering food mixed with small quantities of infected feeces from other Grouse suffering from Coccidiosis, and fatal results ensued. The results set forth in this Memoir are those obtained from one season's work only, to which my investigations were limited. II. Experimental Methods. The birds used in experimental Coccidiosis were Grouse chicks, fowl chicks and young pigeons, all of which were initially healthy. Coccidian oocysts (PI. xxxvni., Figs. 4, 5) contained in cfecal droppings from infected Grouse were allowed to develop spores to some extent by being thinly spread in Petri dishes and covered in order to prevent complete drying. Under these conditions the spores (Figs. 6, 7) developed in two to three days at summer temperature. The ffeces so prepared were then administered to the healthy young birils. (A) Gronse Chicks. — As these birds are somewhat wild, even though bred in captivity, a rapid feeding method was adopted. Some of the partly dried fa'cal matter was taken up on a spatula and inserted directly into the mouth of the bird. Rather large quantities were given as first doses, but if infection was not fairly rapidly brought about the dose was repeated. The c?ecal droppings of treated PLATE XXXVI II. \ !:r.z , -...1.;...;--, liK' H.B.Fantham c- E Wilson, Cambridge. AVIAN COCCIDIOSIS. Ofrjmsite p. 252.] "GROUSE DISEASE"— COCCIDIOSIS 253 chicks were collected each morning, for these soft droppings are more abundant during the night than they are during the day, and in the early morning there is a better chance of obtaining excrement free from soil. Examination of faeces collected in the evening was sometimes made. The Grouse chicks were kept on the experimental ground at Frimley, and the feeding experiments were conducted by Dr E. A. Wilson. Samples of the freces of the birds were sent to me daily. (B) Fowl Chicks and Young Pigeons. — A method of feeding similar to that used for Grouse chicks was employed with fowl chicks and young pigeons (squabs). These experiments were conducted by me at Cambridge. The chicks used were from incubated eggs, the eggs having been carefully cleansed antiseptically before incubation. Ccecal droppings containing oocysts were administered directly to the Ijirds. Very small daily doses were used for several days and then none for a couple of days, and so on. This method of administering oocysts was quite efiective, and had the advantage of reproducing somewhat the condition of wild Grouse on the moors, where intermittent ingestion of oocysts with food or drink occurs. One experiment was performed in which a single dose only had a fatal effect on a fowl chick. Droppings containing oocysts in different stages of development (Figs. 4-7) were also used. When the oocysts contained developed sporocysts the onset of Coccidiosis was more rapid. Again, I have found coccidian oocysts in the water of tarns at which Grouse chicks drink and also in dew collected from the heather on the moors (Fig. 8). Grouse chicks, then, can acquire coccidian oocysts by way of their drink. To show this method of infection experimentally, a healthy fowl chick was supplied with water containing coccidian oocysts. This bird also became infected with Coccidiosis. Control birds were most carefully kept. These were supplied with food and drink exactly as were the treated birds, and kept under the same conditions. Examination of their faeces was made twice daily, and careful search was made for oocysts as the possibility of natural Coccidiosis of both fowls and pigeons ' was well recognised and most carefully guarded against. Control birds were invariably healthy, and made more rapid progress in growth than did the subjects of the experiment. ' Through the courtesy of a friend I was able to examine coccidian oocysts from a pigeon suffering from natural Coccidiosis. On PI. xxxviii., Fig. 13 is drawn a cyst of this Coccidium (C. pfeifferi oi Lahhe). It is spherical, about 17m iu diameter. 254 THE TtROUSE IN HEALTH AND IN DISEASE In every instance I most carefully compared the results obtained experimentally with the cases of natural Coccidiosis in Grouse chicks that I investio-ated on one of Lord Lovat's moors in Inverness-shire, and in other cases obtained from Perthshire, Dumfriesshire and Yorkshire. Some authors have given the name Coccidimn cunicidi ^ to the parasite of birds, thereby identifying the Coccidium of birds with that of rabbits. Having had the opportunity of obtaining fresh material from rabbits dying rapidly of acute Coccidiosis, I fed a healthy young pigeon directly with oocysts of C. cuniculi. At first oocysts were voided by the pigeon, then none were found in tlie fteces, nnd no symptom associated with Coccidiosis appeared at any time. The first 0()cysts voided were merely those supplied to the bird which had passed unchanged through its alimentary tract. Though this pigeon received several doses of the oocysts of Eimeria (Coccidium) cuniculi, it never developed Coccidiosis, and the post-mortem examination made immediately after killing the bird .showed a perfectly normal condition of every organ. I consider that these experiments show conclusively that E. avium and E. eunieuli are distinct species of Eimeria and are not identical. There are also morphological differences between the two, chiefly of size {E. avinni is the smaller). III. Symptoms of Coccidiosis. The symptoms of Grouse suffering from natural Coccidiosis and those of Grouse, fowl chicks, and pigeons, in which the disease has been artificially induced, are identical. The symptoms that have been noted in the case of the birds examined may now be stated. Chicks after ingesting coccidian oocysts become far less active in their move- ments as a rule. The first noticeable feature is the drooping of their wings and a habit of constantly looking downwards. The birds stand about more than normal birds, and their calls are more plaintive. While fowl chicks and pigeons appear to mope, their appetite is increased, and chicks experimentally infected with Coccidiosis eat far more greedily than the control birds. They also drink considerably more. In spite of the increase in the amount of food consumed, the birds rapidly get thinner, the muscles of the breast and legs showing this to a marked degree. Throughout the progress of the disease the growth of the affected birds is much retarded. It was necessary to feed infected young pigeons by hand, for even when they ' The correct nairn' of this parasite is Eimeria stieda: Liudeiiiaiin. GROUSE DISEASE "— COCCIDIOSIS 255 reached practically adult life they failed to feed themselves, merely thrusting their heads into the food oflered them, without attempting to swallow any of it. Several breeds of fowl chicks were used in experimental Coccidiosis, and each lost weight steadily till death occurred. The loss of weight of one pure bred Leghorn chick was very noticeable. It was first fed with coccidiau oocysts when six weeks old. It and its control bird were then of equal weights {7h oz.). Two months later the infected chick died, its weight at death being 5 oz., while the weight of its control on the same day was 1 lb. 6 oz. Sample weights of other experimental birds are given below : — Bum. Weiglit of Infected Bird. Weight of Control Bird. Difference in Weights. Remarks. Grouse chick A . 4oz. •5| oz. 11 OZ. r Dosed once wlien 1 1 days old. Grouse cliick B . Hoz. 7 oz. 2f oz. Killed in extremis when aged 6 weeks. Grouse chick C . 61 oz, 9 oz. 2i oz. Died, aged 10 weeks. Minorca hen 3 \h. 2 oz. 5 lb. 2 oz. 2 lb. Died, aged 6 months. Plymouth Rock cock . 4 lb. 8 oz. 6 lb. 5 oz. 1 lb. 13 oz. Killed, at acute stage of disease. Gross-bred Leghorn ■1 lb. 10 oz. 5 lb. 4 oz. 10 oz. Chronic. Pigeon 9J oz. 12 oz. 21 oz. Died, aged 11 weeks. Note. — The three fowl clucks were first treated with coccidian oocysts when aged three weeks. Another fowl chick fed with coccidian oocysts when aged one day, died when nine days old. The pigeon squab was dosed first when aged nine days. Another instance of loss of weight resultant on Coccidiosis was seen in the case of a pure bred female Leghorn chick which was attacked when seven weeks old by Coccidiosis after drinking water fouled with coccidian oocysts. This bird became " a chronic," and when adult weighed 4 lb. 3 oz., while its sister bird that acted as control weighed 5 lb. 4 oz. Besides loss of weight the infected birds become anaemic. The cere, comb, and wattles become much paler and the blood-vessels beneath the wing also look pale. The head appendages gradually become more and more pale as the disease progresses, and finally acquire a peculiar bluish tinge. This tint also is shown by the eyelids and ears, and the legs are affected, though to a less extent. The feathers on the 256 THE GROUSE IN HEALTH AND IN DISEASE head tend to fall off so that the forepart of the head and the regioii round the bill become almost bald, and the bird presents a very peculiar appearance, owing to the bluish coloration. Leg weakness was present in several cases. The plumage of the infected birds is affected in regions other than the head, and the quills are less rigid than in normal birds. The feathering of the legs is ragged, and the sheen on the neck and tail-coverts is not so well developed, while the replacement of nestling down by ordinary feathers is much retarded in diseased birds. During the progress of Coccidiosis the birds sometimes develop much mucus and a very offensive " breath," a smell of sulphuretted hydrogen being notice- able. Both sticky mucus and smell disappear as a rule in a few days, but may recur. While birds suffering from Coccidiosis feed greedily, internal digestive troubles occur, and the fseces voided by the birds are very fluid, the condition being that of diarrhcea. The caecal droppings are the more noticeable, and they contain many resistant cysts (oocysts) (Figs. 4-8) of C. avium. Both sportsmen and keepers have noted that diarrhoea is a marked symptom of "Grouse Disease." Examination of soft droppings daily shows the relative numbers of oocysts present, and may be a rough gauge of the intensity of the infection.^ In good health the cascal drojjpings are of firm consistency and olive-green to brown in colour. When Coccidiosis is slight, the fgeces become softer and brownish yellow. In acute cases the excrement is almost fluid, and the birds void sulphur-yellow faeces with a heavy, foetid odour. Fatty matters may be present in the cascal contents. A day or so before the death of the infected bird the slimy, mucilaginous dis- charge recommences, ooze coming from the beak, nares, ears, and eyes. Examina- tion of this liquid by the microscope shows the presence of oval coccidian oocysts {cf. PI. xxxviii.. Figs. 4-8), all of which show the characteristic cyst- wall within which is a single uninucleate mass of protoplasm. The mucus also contains some shed epithelial cells in which occasionally macro- and micro-gametes may be found. The ooze from the eyes and beak chiefly contains oocysts which may be due to regurgita- tion from the crop just before death. However, it should be noted that while raucous discharge is common, it is not an invariable feature of Coccidiosis. Death from Coccidiosis appears to be sudden. Some of the experimental fowl chicks were feeding greedily an hour before death, though death was almost ' It should be noted that in severe cases of duodenal Coccidiosis, merozoites may be found free in the gut contents and faces of infected birds when no oocysts are present. "GROUSE DISEASE "—COCCIDIOSIS 257 expected from the great emaciation and " bluish " appearance of the birds for some days previous to the actual decease. All infected corpses should be burned, not buried. IV. Internal Organs. Detailed examination of diseased birds shows that Coccidiosis of fowls, pigeons, and young Grouse is confined chiefly to the digestive tract, and so is unlike the Coccidiosis of the rabbit, where both the liver and the gut may be affected. Dead chicks have shown oval coccidian oocysts (Text-Fig. 2, p. 258) in the discharge from the nostrils. Scrapings from the soft palate, trachea, and oesophagus of diseased birds have shown the presence of oocysts embedded in mucilage. Possibly the oocysts may have regurgitated from the gizzard or intestine. Oocysts are occasionally present in the crop and gizzard, mixed with crushed food, having been probably taken up with the food. The intestine is more highly parasitised than any other part of the alimentary tract. The oocysts (PI. xxxviii.. Figs. 7, 8, 11, 12), which show much variation among themselves, are softened by the pancreatic juice, the four sporocysts (Figs. 9, 10) emerge, and from each of them two active, motile sporozoites or germs come out and proceed to attack the epithelium of the duodenum. Having penetrated the epithelium (Fig. 1) they become round, grow and produce individuals, destined to divide and give rise to a barrel-shaped mass of active daughter germs, the merozoites (Fig. 1, mt). These merozoites separate from one another and infect fresh epithelial cells, the whole mucous membrane being soon badly infested, and becoming reduced to an almost structureless mass (Fig. 1). Owing to heavy infection in the duodenal epithelium, death of the young Grouse may occur. However, in many cases, some of the merozoites pass into the lumen of the gut and reach the caeca, the tissues of which are similarly mutilated. As far as my experiments go at present, the full period of schizogony would appear to be from four to five days, as judged by the appearance and general moping of the birds. After several generations of merozoites have been produced, the power of the host to provide food for the parasite fails, and consequent on this, the latter begins to make preparation for extra-corporeal life, and produces large, granular forms, which are female (mother) cells or macro-gametocytes (Fig. 1, ?) and somewhat smaller, less granular ones which are micro-gametocytes (Fig. 2, 6). Each macro- gametocyte gives rise to one passive macrogamete or female element (Fig. 1), while VOL. I. E 258 THE GROUSE IN HEALTH AND IN DISEASE each micro-gametocyte gives rise to many minute, motile microgametes, the male elements (Fig. 2). Fertilisation (Fig. 3) occurs through a micropyle left in the wall with which the macrogamete invests itself, and the fertilised oocyst so produced, passes out through the much damaged epithelium into the lumen of the gut and thence to the outside. The epithelium of the duodenum and cseca is sometimes Text Fig. 2. Figs. A-F. Stages in the development of the oocysts of Eimeria avium, as seen in fresh preparations. A. Oocyst (encysted zygote) with protojilasm coiupletely filling it. B. Older oocyst with zygote contents forming a central sphere. Many such cysts are found in infected cteca and infected fieces of Grouse. C. Oocyst with four nuclei, about to form sporoblasts. D. Oocyst with four round sporoblasts. E. Four ovoid sporocysts within oocyst. F. Fully mature oocyst with four sporocysts, each containing two sporozoites, entirely denuded by the action of the many parasites that infest it, and the sub- mucosa also is sometimes infected by the Eimeria. The contents of the oocyst, at first filling the interior (Text-Fig. 2, A), gradually contract (Text-Fig. 2, B), towards the centre, or occasionally towards one pole, and then divide (Text-Fig. 2, C) into four round masses (Text-Fig. 2, D) known as sporoblasts. Each sporoblast becomes an oval sporocyst (Text-Fig. 2, E) while still within the oocyst, and within each ripe sporocyst two sporozoites or germs are developed. Consequently each oocyst gives rise to eight sporozoites (Test- Fig. 2, F). "GROUSE DISEASE "—COCCmiOSIS 259 A certain amount of variation, as exhibited by the oocysts of ^. avium, has been noticed by Morse (1908) in the coccidian parasite of " white diarrhoea" of fowls, where the oocysts are round to oval, and from 12m to 25^1 in diameter. The oocysts of E. avium in Grouse, which is identical with the parasite found in " white diarrhoea " of fowls, also vary among themselves. Usually the oocysts are oval (PI. xxxviir., Figs. 4-8), but a series of varying sizes and shapes can readily be found (Figs. 8, 11, 12, 14), while round oocysts also occur (Fig. 11). The exact shape and size of the oocyst is determined by the space in the cell available for the development of the macrogamete, and should not be insisted upon as a specific character, for where many parasites are aggregated together in a limited area of epithelium, the macrogametes and oocysts are small, while in areas of the gut but poorly parasitised, large oocysts preponderate. Nutrition of the parasite has obviously a great influence on both its size and its propagative power. In some cases the gut- wall is extremely thin and tender ; in other birds this^ effect is not marked. Inflammatory patches may be seen at intervals, particularly in the caeca, and the cagca usually are enlarged. At the ileo-csecal junction, where a recurrence of schizogony and sporogony occurs, much degenerated epithelium is present in the gut contents, and this epithelium contains both schizonts and gametocytes. The large intestine of chicks infected with Coccidiosis sometimes shows inflammatory patches, and blood may be present in the rectal contents. The rectum itself seems rarely to be attacked by E. avium, though its contents usually contain oocysts. The kidneys, spleen, liver, and gall-bladder of birds suflering from Coccidiosis never contained Eimeria, though the spleen and gall-bladder were sometimes enlarged. Examination of the generative organs has shown no stage of E. avium so far, though it is possible that eggs may become contaminated during their passage through the cloaca of the mother. The young chicks then might be hatched in contact with infectious material, and so acquire Coccidiosis early in life. Eight days old Grouse chicks were the youngest naturally infected chicks that I examined. The period of eight to ten days is the one determined roughly by my experiments as being required for the complete developmental cycle of E. avium in fowls and pigeons, from the time of ingestion of the oocysts to the excretion of the maximum number of oocysts of the second generation. Many bacteria are present naturally in the gut of the Grouse, and their active movements can be well seen, especially in the ceecal contents of freshly killed 260 THE GROUSE IN HEALTH AND IN DISEASE Orouse. Examination of sections of the gut of the Grouse, especially of sections stained with iron-heematoxylin and iron-htematoxylin followed by Van Gieson's stain, reveals the presence of numerous bacteria, which are present, not only in the lumen of the gut, but forming a layer along the striated edge of the columnar epithelial cells, and also are found in lesions left by the outward passage of gametes and merozoites. These bacteria may have a harmful effect on the tissues invaded, and there is evidence to show that they gain access to the tissues very early, the sporozoites and merozoites acting, in fact, as inoculating needles, whereby the injurious bacteria are passed into the tissue of the gut, whence, by way of the blood and lymph, they can reach other organs. Further, the denudation of the epithelium of the gut allows of easy entry of bacterial agents of infection. In connection with the action of bacteria in the disease of fowls known as " white diarrhoea," there are two opposing views. Morse (1908), working in America, has investigated white diarrhoea in fowls and other l)irds, and always found intestinal Coccidiosis. Hadley (1909), also working on the subject, found not only intestinal but also hepatic Coccidiosis in fowls suffering from white diarrhcea. Morse notes the presence of bacteria in the gut, and thinks that they may gain access to the system on account of the denudation of the gut epithelium. Rettger (1909), on the other hand, considers that white diarrhoea is due entirely to a bacterium. Bacterium septicemice gallinarum or Bacterium pullortim. Probably both of these conflicting views are right as far as they go, but separately they may only partially explain the cause of " white diarrhoea." Drs Cobbett and Graham-Smith have shown (1910) experimentally that bacteria may be inoculated by means of Coccidia, and find their way into the internal organs probably by way of the portal vein (vide chapter xii. p. 295 et seq.). The agency of parasitic worms and Coccidia in causing lesions of the mucous membrane througli which harmful bacteria may enter is of far-reaching importance, and probably of wide application in the elucidation of certain intestinal diseases. Morse's paper gives much valuable information regarding treatment of Coccidiosis .and brief notes on intestinal Coccidiosis of various birds. Game birds other than Grouse are susceptible to Coccidiosis, for M'Fadyean reported Coccidiosis in Pheasants in 1893-1894. At the time of correcting proofs of this article I am engaged in investigating Coccidiosis which is causing the death of many young Pheasants in various parts of England. The onset of sporogony of E. avium means, as a rule, either the recovery or the