Br. vel.}. ( 1977 ), 133 , 32 7
THE RESULTS O F POST- M ORTEM EXAM INATI O N OF 13 2 WILD BIRDS By j . R . B AK ER
Clinical Pathology Unit, Department of Veterinary Pathology, University of Liverpool, Leahurst, N eston, Wirral
S U MMAR Y
T his pa per records the post-mortem findings of 132 wild b irds fo und dead or dying. Thirty- three per cent of the birds died of infectious di seases, 27% were poiso ned , 16% had traumatic injuries, 2% were severely infested with parasites a nd in 9% no diagnosis was reached . The remaining 13% died of miscellaneo us ca uses. These res ults are similar to those reported by McDo nald (I 965), j ennings (I 961 ) a nd Keymer (I9 58 ).
INTROD UCT IO N
There have been a number of surveys of d eath s of wi ld birds (McDiarmid, 1962, 1965; McDonald , 1962, 1963, 1965 ; jennings, 1961 ; Keymer , 1958) some specifi cally rela ted to raptors (Weir, 1971 ; Cooper, 1972 ; Keymer , 197 2) whilst Blackmore & Keymer (I969) rep orted o n cuta neo us diseases. Several o f these repo rts include qui te large numbers of p ost-mo rtem examinatio ns on captive birds. Th ere are also very ma ny reports in th e litera ture of exa mina ti o ns post mortem of sm all numbers or individual birds. Saunders et al. (I 96 I) in a report on toxic chemicals in agriculture sta ted 'a majo r difficulty in the investigation of some of the causes of m ortality of birds and m amma ls in the fie ld has been the lack o f knowledge o f the habi ts and circumstances of na tural death of the vario us species', and it is therefore considered that a fu rther rep ort may be of interest.
MATE RI ALS AN D MET HOD S
The b ird s were either picked up dead or they died in captivity after being found ill o r inj ured. Birds which had been in captivity for more tha n three days are excluded fro m this report to avo id conditio ns associated with captivi ty. Also excluded a re bird s fo und dead o n roads a nd those on beaches with significant degrees o f oiling of th e plumage. T he birds were examined post mortem with bacteri ologica l and histological exami natio ns where indicated and chemical assays were a lso performed o n samples rrom some birds in which poisoning was suspected .
328
BRITI SH VETE RI
RESU LTS A
ARY JO UR N AL , 133,4
D DI SCUSS IO N
One hundred a nd thirty- two birds, of 33 species, were obtained ; o f these 54 were ma les, 52 females and in 26 the sex was no t recorded . With th e excep ti on o f 12 specim ens th ey were all from the Wirral area of Cheshire. The resu lts a re presented in T ables I and II. Table I gives the co ndi tion considered re po nsib le for death a nd Ta ble II li sts oth er abno rmalities foun d, som e of which may have played a minor part in causing death . The generic na me is given for each sp ecies the fi rst time it a ppears in the Ta bles. The bacteria listed a re no t necessaril y consid ered pa thogenic, except where indi cated . De tails o f th e m ore interesting or unu sual co nditio ns a re given below. A corncra ke, which was considered to have died of enteritis and which also had a hea ling fracture o f the wing, was fo und in a pile of scra p meta l in a shipbuilding yard at leas t three miles from the nearest op en country but was in good fat co nd itio n. Two yo ung kestrels died o f starvation due to the fo rmation o f granul omas, o ne abo ut 1 cm across, at the commisures o f the beak and inside the cheek. Cooper ( J 972) b riefl y describes a simila r co nditio n in a captive goshawk. The other was fo und subcutaneously a t the base of the neck o ccluding the oesophagus and causing la teral di splaceme nt o f the trachea. In neither case was the cause of the granul o ma discovered bu t it is proba ble tha t they fo llowed mino r trauma . A ph easant also died o f starvation fo llowing fractures o f the left mandible and zygoma. These had healed and fu sed together so that the bird was unable to op en its mouth resulting in gross overgrowth of the beak before it died in an emaciated state. There were fo ur cases of Salmonella typhimurium septicaemia in sparrows which were asso cia ted with cases in canaries and peafowl o n a bird farm . Whe th er the wild birds affected the captive o nes or vice versa cou ld not be discovered . Outbreaks of salmonellosis in hou se sparrows and greenfinches have been described by McDonald & Cornelius (J 969 ) bu t th e gross les io ns seen by these a uthors in a proportio n of the cases were no t seen in the birds in the present study. Five birds died of interna l haemorrhage, fo u r of ruptu res of the great vessels near the heart, but histology revealed no changes o th er tha n the recent rupture. The case in the wood-pigeon was striking as the bird was under o bserva tion wh en it was seen to literally fall out of the sky, post-m o rtem examinatio n revealed massive internal haemorrhage from a rupture of the aorta 4 mm from its origin . Th e fi fth death associated with haemorrhage presented as extensive subdural haemorrhage with no evidence of tra uma. A fl edgling cu ckoo died of a naemia, fo llowing aplasia of the haem op oietic tissue, none of wh ich could be found eith er in th e bo ne ma rrow or so ft tissues such as liver. A tawny owl, which had b een o bserved fo r several days partially pa ralysed in bo th legs and the left wing, was fo und dead . At postmo rtem examina tion there were lesions on the sciatic nerves and left brachia l plexus whi ch were indistinguishable from Mareks disease. Similar lesio ns h ave been reported in a pa rtridge (Je nnings , 1954 ) and sparrow- hawks (Woodfo rd & Glas ier, 1955) . Unfortunately no case has been examined for presence o f virus. Muscula r degeneration , similar histolo gically to nutritional muscular dystrophy as seen in mammals, was seen in the pectoral muscles of a collar ed dove which was observed unabl e to fl y and with its wings trailing on the ground. Histological examinati o n of th e pectoral muscles o f a sta rling fo und dead revealed evidence of repeated episodes o f d egenerati o n.
POST-MORTEM EXAM INATION OF WILD BIRDS
329
TABLE I CAUSES OF DEATH , LISTING LESIONS AND WHEN POSSIBLE THE CAUSE
Lesions involving one system Alimentary system Enteritis 3 Guillemots Uria aalge (Escherichia coli-2 , oil in intestine- I), 2 Razorb ills Alca torda (E. coli and oil- I), I Herring gull LaTUS argentatus (Streptococcus sp. and E. coli) , I Gannet Sula bassana (oil in intestine), I Kestrel Falco tinnunculus (Staphylococcus sp.), I Corncrake Crex crex. Hepatic necrosis I Guillemot (oil), I Bullfinch Pyrrhula pyrrhula. Parasitic enteritis 2 Guillemots (Cosmocephalus sp.), I Blackbird Turdus merula (Cestode). Starvation I Gannet (following oiling), I Kestrel (granuloma in mouth-I and In neck- I), I Pheasant Phasianus colchicus (fractured jaw) Impacted intestine I Great crested grebe Podiceps cristatus (food ), I Blackbird (helminths), I Mute swan Cygnus olor (vegetable fibres ), Salmonellosis 4 House sparrows Passer domesticus (Salmonella typhimurium). Respiratory system Pneumonia I Oyster-catcher Haematopus ostralegus (E . coli), I Lapwing Vanellus vanellus. Aspergillosis 3 Gui llemots; I Oyster-catcher, I Blackheaded gull Larus ridibundus, I Lapwing. Vascular and haemopoietic system Haemorrhage I Guillemot, I Tawny owl Strix aluco, I Scoter Melanitta nigra, I Magpie Pica pica, I Wood-pigeon Columba palumbus. Bone marrow ap lasia I Cuckoo Cuculus canorus. Urinary system, renal infarction I Little owl Athene noctua. Nervous system Mareks disease (suspected ) I Tawny owl Locomotor system Muscular degeneration I Collared dove Streptopelia decaocto, I Starling Sturnus vulgaris. Multiple exostosis I Gannet. Lesions involving multiple systems Sepsis and septicaemia I Tawny owl (Pasteurella septica), I Sparrow-hawk Accipiter nisus (Mixed, following fracture of wing), 3 Partridge Perdix perdix (Pasteurella septica-2, Streptococcus sp.-I), 2 Pheasants (Streptococcus sp .-I , E. coli-I), I Blackbird (E. coli), I Dove (Corynebacterium sp.), I Wood-pigeon (Pasteurella septica). Tuberculosis I Heron Ardea cinerea, I Wood-pigeon . Poisoning 20 House sparrows (Chlorine-12), 12 Starlings, I Wood-pigeon (a chloralose), I Magpie (Strychnine), I Raven Corvus corax (Strychnine).
330
1
BRITISH VETERINARY JOURNAL, 133,4
Neoplasia I Tawny owl. Ascites I Kestrel Stress I Black-throated diver Cavia arctica. Shock I Crow Corvus corone. Drowned I Roo k Corvusfrugilegus. Trauma I Guillemot, I Oyster-catcher, 2 Tawny o wls, I Kes trel, 2 Bullfinch, 2 Chaffinch Fringilla coelebs, I Hero n , 7 House sparrows, I Wood-pigeon, I H erring gu ll , I Gannet, I Raven, I Blue-tit Parus caeruleus. No cause of death found 2 Guillemots, I Manx shearwater Pulfinus pulfinus, I O yster-catcher, I Common gull Larus canus, 2 Scoter, I Tawny owl, I House sparrow, I Starling, I Collared dove, I Greater spotted woodpecker Dendrocopos major, I Blue- tit.
With regard to the secondary lesions found (Table II) hepatosis and nephrosis were frequent findings, both conditions occurring in five birds, two had nephrosis alone. These changes were considered to have been due to the ingestion of oil although little or none was found on the plumage. These lesions have been reported frequently in publications dealing with oiling of seabirds (Anon, 1970, 1971 , 1972 , 1973, 197 4). Mycotic oesophagi tis was seen in three guillemots, fungal mycelia was seen in sections of this organ but no cultural work was carried out. Three birds had arthritis of the ti b io tarsal -phalangeal joints. Two birds were received with abnormal feathers . One was a fl edgling rook which had extreme fragility of the large wing and tail feathers, many of whi ch were broken. The feather shafts varied greatly in thickness, the primary and secondary raphes were absent or malformed and the feather sheaths did not break off regularly; one was 4 in long. Another fledgling in the nest was also known to b e affected . Feath ers were also received from another rook fledgling with a similar condition from another part of the country. The lesions were similar to those seen in domestic fowl (Jordan, personal communication) due to cysteine or methionine deficiency, although other causes cannot be excluded. The body of a lapwing was almost totally bald ; histology of the skin showed atrophy of the feather follicles, these being represented by a few inactive cell clusters, the skin in general was hyper-plastic with accumulation of kera tin, containing large numbers of organisms resembling yeasts and also staphylococci, but whether these were primary or secondary to some other condition is impossible to say. A number of cases of partial or total alopecia have been recorded by Blackmore & Keymer (1969) but these were almost all of unkown etiology. A number of cases of sepsis and septicaemia are listed in Table I and the bacteria listed in this section are considered to be pathogenic and to have caused the condi tions listed. Similar lists of pathogenic bacteria are given by MacDonald (1965), J ennings (1954 ) and McDiarmid (1965 ). The only organism which was reported by these three authors not seen in the present survey was Pasteurella pseudo-tuberculosis. Two cases of
POST-MORTEM EXAM I ATIO
OF WILD BIRDS
33 1
TABLE II SEeo DARY LESIONS
Enteritis I Little owl, I Blackbird. Hepatosis and nephrosis I Black-headed gull, I Common gull , I Herring gull, I Scoter , 2 Guillemots. Hepatic infarct I Starling. Parasitic enteritis 3 Guillemots (Cosmocephalus sp.), 2 Gannets (nematode), I Starling (ces tode). Impacted cloaca I Guillemot (urates). Myco tic oesophagi tis 3 Guillemots. Ulcerated gizzard I Black-throated diver, 1 Great spotted woodpecker, 1 Mute swan. Pneumonia 1 Sparrow-hawk. Aspergilfosis (healed) 1 Scoter. Syngamus trachea 1 Crow. Visceral Gout 1 Starling. Arthritis I Guillemot, 1 Oyster-catcher, 1 Pheasant. Sepsis I Herring gull. Pan-ophthalmitis 1 Oyster-catcher, 1 Tawny owl. Trauma 1 Tawny owl, 1 Corncrake, 1 Blackbird. Abnormal Feathers 1 Rook, 1 Lapwing. Lice 1 Wood-pigeon (Coloceras sp.).
tuberculosis were found. The first was in a wood-pigeon with the typical dark plumage (McDiarmid, 1948 ) in which lesions were widely disseminated throughout the carcass and from which the typical avian strain of Mycobacterium avian was recovered. The second case was in a heron found dead in the grounds of a zoological garden at a time when avian tuberculosis was a problem in exhibited species. The heron could have had access to a number of pens were the disease was occurring. The post-mortem examination of the heron revealed a fusiform mass 9 cm x 2 cm of a uniform meaty texture in the position of the pancreas and, until histological examination revealed this to be of tuberculosis, it was considered to be a pancreatic neoplasm. A number of the cases of poisoning were of interest. Twelve sparrows were received out of a total of 32 found dead one morning in one room of a firm producing specialized metal castings and similar products. The room was large and airy with a number of opening sky-lights through which the sparrows were readily gaining access
332
BRITISH VETERINARY JOURNAL, 133,4
to the building, the evening before the deaths occurred the majority of the sky-lights were closed for the first time for several months. We were consulted to see if there was any risk to human beings but post-mortem examination of the birds revealed congestion and haemorrhage in the lungs of a non-specific type. We were later informed by the company that a process had been incorrectly set up to run over the night in question and considerable quantities of chlorine gas had been liberated . Eight sparrows were received for examination out of a total of 114 found dead after a corn crop had been sprayed by a helicopter but it was not possible to discover the nature of the agent sprayed. Similarly 12 starlings were considered to have been poisoned bu t the agent was not discovered. The birds were found dead over a small area of a recently sown field and the finder reported that the birds were 'unusually rigid and in peculiar positions' . There were no macroscopic lesions. In retrospect it is considered possible that this was mercury poisoning. A wood-pigeon was found in a town garden with clinical symptoms, prior to death, suggestive of a chloralose poisoning. This drug was being used to control feral pigeons in the area at the time. A magpie and a raven were found dead on open moorland close to the opened carcass of a rabbit which had obviously been shot. Analysis of the gizzard contents of both birds revealed large amounts of strychnine together with pieces of rabbit intestine. We were also involved with strychnine-injected hens eggs left on a public footpath, presumably with the object of poisoning crows. Two dogs ate one of the eggs and died and analysis of another egg revealed sufficient strychnine to kill approximately 20 people. The incidence of poisoned birds reported here is probably higher than its incidence in the avian population as a whole. The reasons for this are that mass deaths attract the interest more than individual deaths. Neoplasia was found in a tawny owl which had an anaplastic tumour of the tissues of the posterior part of the mouth, nares and upper part of oesophagus and larynx. Most authors agree that neoplasia is relatively uncommon in wild birds with th e exception of squamous papillomas of the feet of chaffinches (Blackmore & Keymer, 1969; Keymer & Blackmore, 1964). The examination post mortem of a black-throated diver revealed the presence of minute adrenal glands, about quarter the size of those in a bird of the same species which had been in captivity for three months following fracture of the wing. The author has seen similar atrophy of the adrenals of some species of birds in zoological gardens where the lesions were considered to be exhaustion atrophy following prolonged stress. A fledgling crow was considered to have died of shock; it fell out of the nest, being unable to fly due to a feather defect (vide infra), into a bowl of water, was immediately rescued but died three minutes later. A number of birds died of trauma, a proportion of these were almost certainly traffic accidents but as they were found away from the immediate vicinity of roads , they had presumably died a little while after being hit. A heron was found under some power lines, a gannet with extensive fractures of the skull was found at the base of a cliff, and a raven and an oyster-catcher had been shot. REFERENCES
(1970, 1971, 1972, 1973, 1974). lst, 2nd, Jrd, 4th and 5th Annual Reports of the Advisory Committee on Oil Pollution of the Sea, Research Unit on the Rehabilitation of Oiled Seabirds. Department of Zoology, University of Newcastle-upon-Tyne.
A NON,
POST-MORTEM EXAMINATION OF WILD BIRDS
333
BLAC KMORE, D. K. & KEYMER, I.F. ( 1969 ). Br. Birds, 62, 316. COOPER, J.E. ( 1972). Veterinary Aspects of Captive Birds of Prey, The Hawk Trust, Newent, Clo u cestershire . J EN NINGS, A . R . ( 1954 ).j. compo Path. 64,356 . JENNINGS, A. R. ( 196 I). Bird Study, 8, 25. KEYMER, I. F. (1958). Vet . Rec. 70, 713 and 736. KEYMER, I. F. (1972 ). Vet. Rec. 90,579 . KEYMER, I. F. & BLACKMO RE, D . K. (1964 ). Br. Birds, 57,157. MAC DIARMID, A. (I 948 ).}. compo Path. 58,128. MAC DIARMID, A . (J 962 ). Disease of Free Living Wild Animals. Rome: F.A.O. MAC DIARMID, A. (1965 ). Br. vet.}. 121,245 . M c DoNALD, J. W. ( 1962). Bird Study, 9, 147. Mc DONALD,]. w. (1963). Bird Study, 10,91. McDoNA LD,]. W . (1965 ). BirdStudy, 12, 181. M c DONALD, ]. W. & CORNELI US, L . W. (1969 ). Br. Birds, 62, 28. SAUNDE RS, H. E. et at. (196 I). Cited by McDonald,]. W. (1963). Bird Study, 10,91. WEIR, D . N. (J 97 I). Bird Study, 18, 147 . WOODFO RD, M. & CLASIER, P. E . B. (1955 ). Falconer, 3, 63.
(Acceptedfor publication 26 August 1976)
THE RESULTS O F POST- M ORTEM EXAM INATI O N OF 13 2 WILD BIRDS By j . R . B AK ER
Clinical Pathology Unit, Department of Veterinary Pathology, University of Liverpool, Leahurst, N eston, Wirral
S U MMAR Y
T his pa per records the post-mortem findings of 132 wild b irds fo und dead or dying. Thirty- three per cent of the birds died of infectious di seases, 27% were poiso ned , 16% had traumatic injuries, 2% were severely infested with parasites a nd in 9% no diagnosis was reached . The remaining 13% died of miscellaneo us ca uses. These res ults are similar to those reported by McDo nald (I 965), j ennings (I 961 ) a nd Keymer (I9 58 ).
INTROD UCT IO N
There have been a number of surveys of d eath s of wi ld birds (McDiarmid, 1962, 1965; McDonald , 1962, 1963, 1965 ; jennings, 1961 ; Keymer , 1958) some specifi cally rela ted to raptors (Weir, 1971 ; Cooper, 1972 ; Keymer , 197 2) whilst Blackmore & Keymer (I969) rep orted o n cuta neo us diseases. Several o f these repo rts include qui te large numbers of p ost-mo rtem examinatio ns on captive birds. Th ere are also very ma ny reports in th e litera ture of exa mina ti o ns post mortem of sm all numbers or individual birds. Saunders et al. (I 96 I) in a report on toxic chemicals in agriculture sta ted 'a majo r difficulty in the investigation of some of the causes of m ortality of birds and m amma ls in the fie ld has been the lack o f knowledge o f the habi ts and circumstances of na tural death of the vario us species', and it is therefore considered that a fu rther rep ort may be of interest.
MATE RI ALS AN D MET HOD S
The b ird s were either picked up dead or they died in captivity after being found ill o r inj ured. Birds which had been in captivity for more tha n three days are excluded fro m this report to avo id conditio ns associated with captivi ty. Also excluded a re bird s fo und dead o n roads a nd those on beaches with significant degrees o f oiling of th e plumage. T he birds were examined post mortem with bacteri ologica l and histological exami natio ns where indicated and chemical assays were a lso performed o n samples rrom some birds in which poisoning was suspected .
328
BRITI SH VETE RI
RESU LTS A
ARY JO UR N AL , 133,4
D DI SCUSS IO N
One hundred a nd thirty- two birds, of 33 species, were obtained ; o f these 54 were ma les, 52 females and in 26 the sex was no t recorded . With th e excep ti on o f 12 specim ens th ey were all from the Wirral area of Cheshire. The resu lts a re presented in T ables I and II. Table I gives the co ndi tion considered re po nsib le for death a nd Ta ble II li sts oth er abno rmalities foun d, som e of which may have played a minor part in causing death . The generic na me is given for each sp ecies the fi rst time it a ppears in the Ta bles. The bacteria listed a re no t necessaril y consid ered pa thogenic, except where indi cated . De tails o f th e m ore interesting or unu sual co nditio ns a re given below. A corncra ke, which was considered to have died of enteritis and which also had a hea ling fracture o f the wing, was fo und in a pile of scra p meta l in a shipbuilding yard at leas t three miles from the nearest op en country but was in good fat co nd itio n. Two yo ung kestrels died o f starvation due to the fo rmation o f granul omas, o ne abo ut 1 cm across, at the commisures o f the beak and inside the cheek. Cooper ( J 972) b riefl y describes a simila r co nditio n in a captive goshawk. The other was fo und subcutaneously a t the base of the neck o ccluding the oesophagus and causing la teral di splaceme nt o f the trachea. In neither case was the cause of the granul o ma discovered bu t it is proba ble tha t they fo llowed mino r trauma . A ph easant also died o f starvation fo llowing fractures o f the left mandible and zygoma. These had healed and fu sed together so that the bird was unable to op en its mouth resulting in gross overgrowth of the beak before it died in an emaciated state. There were fo ur cases of Salmonella typhimurium septicaemia in sparrows which were asso cia ted with cases in canaries and peafowl o n a bird farm . Whe th er the wild birds affected the captive o nes or vice versa cou ld not be discovered . Outbreaks of salmonellosis in hou se sparrows and greenfinches have been described by McDonald & Cornelius (J 969 ) bu t th e gross les io ns seen by these a uthors in a proportio n of the cases were no t seen in the birds in the present study. Five birds died of interna l haemorrhage, fo u r of ruptu res of the great vessels near the heart, but histology revealed no changes o th er tha n the recent rupture. The case in the wood-pigeon was striking as the bird was under o bserva tion wh en it was seen to literally fall out of the sky, post-m o rtem examinatio n revealed massive internal haemorrhage from a rupture of the aorta 4 mm from its origin . Th e fi fth death associated with haemorrhage presented as extensive subdural haemorrhage with no evidence of tra uma. A fl edgling cu ckoo died of a naemia, fo llowing aplasia of the haem op oietic tissue, none of wh ich could be found eith er in th e bo ne ma rrow or so ft tissues such as liver. A tawny owl, which had b een o bserved fo r several days partially pa ralysed in bo th legs and the left wing, was fo und dead . At postmo rtem examina tion there were lesions on the sciatic nerves and left brachia l plexus whi ch were indistinguishable from Mareks disease. Similar lesio ns h ave been reported in a pa rtridge (Je nnings , 1954 ) and sparrow- hawks (Woodfo rd & Glas ier, 1955) . Unfortunately no case has been examined for presence o f virus. Muscula r degeneration , similar histolo gically to nutritional muscular dystrophy as seen in mammals, was seen in the pectoral muscles of a collar ed dove which was observed unabl e to fl y and with its wings trailing on the ground. Histological examinati o n of th e pectoral muscles o f a sta rling fo und dead revealed evidence of repeated episodes o f d egenerati o n.
POST-MORTEM EXAM INATION OF WILD BIRDS
329
TABLE I CAUSES OF DEATH , LISTING LESIONS AND WHEN POSSIBLE THE CAUSE
Lesions involving one system Alimentary system Enteritis 3 Guillemots Uria aalge (Escherichia coli-2 , oil in intestine- I), 2 Razorb ills Alca torda (E. coli and oil- I), I Herring gull LaTUS argentatus (Streptococcus sp. and E. coli) , I Gannet Sula bassana (oil in intestine), I Kestrel Falco tinnunculus (Staphylococcus sp.), I Corncrake Crex crex. Hepatic necrosis I Guillemot (oil), I Bullfinch Pyrrhula pyrrhula. Parasitic enteritis 2 Guillemots (Cosmocephalus sp.), I Blackbird Turdus merula (Cestode). Starvation I Gannet (following oiling), I Kestrel (granuloma in mouth-I and In neck- I), I Pheasant Phasianus colchicus (fractured jaw) Impacted intestine I Great crested grebe Podiceps cristatus (food ), I Blackbird (helminths), I Mute swan Cygnus olor (vegetable fibres ), Salmonellosis 4 House sparrows Passer domesticus (Salmonella typhimurium). Respiratory system Pneumonia I Oyster-catcher Haematopus ostralegus (E . coli), I Lapwing Vanellus vanellus. Aspergillosis 3 Gui llemots; I Oyster-catcher, I Blackheaded gull Larus ridibundus, I Lapwing. Vascular and haemopoietic system Haemorrhage I Guillemot, I Tawny owl Strix aluco, I Scoter Melanitta nigra, I Magpie Pica pica, I Wood-pigeon Columba palumbus. Bone marrow ap lasia I Cuckoo Cuculus canorus. Urinary system, renal infarction I Little owl Athene noctua. Nervous system Mareks disease (suspected ) I Tawny owl Locomotor system Muscular degeneration I Collared dove Streptopelia decaocto, I Starling Sturnus vulgaris. Multiple exostosis I Gannet. Lesions involving multiple systems Sepsis and septicaemia I Tawny owl (Pasteurella septica), I Sparrow-hawk Accipiter nisus (Mixed, following fracture of wing), 3 Partridge Perdix perdix (Pasteurella septica-2, Streptococcus sp.-I), 2 Pheasants (Streptococcus sp .-I , E. coli-I), I Blackbird (E. coli), I Dove (Corynebacterium sp.), I Wood-pigeon (Pasteurella septica). Tuberculosis I Heron Ardea cinerea, I Wood-pigeon . Poisoning 20 House sparrows (Chlorine-12), 12 Starlings, I Wood-pigeon (a chloralose), I Magpie (Strychnine), I Raven Corvus corax (Strychnine).
330
1
BRITISH VETERINARY JOURNAL, 133,4
Neoplasia I Tawny owl. Ascites I Kestrel Stress I Black-throated diver Cavia arctica. Shock I Crow Corvus corone. Drowned I Roo k Corvusfrugilegus. Trauma I Guillemot, I Oyster-catcher, 2 Tawny o wls, I Kes trel, 2 Bullfinch, 2 Chaffinch Fringilla coelebs, I Hero n , 7 House sparrows, I Wood-pigeon, I H erring gu ll , I Gannet, I Raven, I Blue-tit Parus caeruleus. No cause of death found 2 Guillemots, I Manx shearwater Pulfinus pulfinus, I O yster-catcher, I Common gull Larus canus, 2 Scoter, I Tawny owl, I House sparrow, I Starling, I Collared dove, I Greater spotted woodpecker Dendrocopos major, I Blue- tit.
With regard to the secondary lesions found (Table II) hepatosis and nephrosis were frequent findings, both conditions occurring in five birds, two had nephrosis alone. These changes were considered to have been due to the ingestion of oil although little or none was found on the plumage. These lesions have been reported frequently in publications dealing with oiling of seabirds (Anon, 1970, 1971 , 1972 , 1973, 197 4). Mycotic oesophagi tis was seen in three guillemots, fungal mycelia was seen in sections of this organ but no cultural work was carried out. Three birds had arthritis of the ti b io tarsal -phalangeal joints. Two birds were received with abnormal feathers . One was a fl edgling rook which had extreme fragility of the large wing and tail feathers, many of whi ch were broken. The feather shafts varied greatly in thickness, the primary and secondary raphes were absent or malformed and the feather sheaths did not break off regularly; one was 4 in long. Another fledgling in the nest was also known to b e affected . Feath ers were also received from another rook fledgling with a similar condition from another part of the country. The lesions were similar to those seen in domestic fowl (Jordan, personal communication) due to cysteine or methionine deficiency, although other causes cannot be excluded. The body of a lapwing was almost totally bald ; histology of the skin showed atrophy of the feather follicles, these being represented by a few inactive cell clusters, the skin in general was hyper-plastic with accumulation of kera tin, containing large numbers of organisms resembling yeasts and also staphylococci, but whether these were primary or secondary to some other condition is impossible to say. A number of cases of partial or total alopecia have been recorded by Blackmore & Keymer (1969) but these were almost all of unkown etiology. A number of cases of sepsis and septicaemia are listed in Table I and the bacteria listed in this section are considered to be pathogenic and to have caused the condi tions listed. Similar lists of pathogenic bacteria are given by MacDonald (1965), J ennings (1954 ) and McDiarmid (1965 ). The only organism which was reported by these three authors not seen in the present survey was Pasteurella pseudo-tuberculosis. Two cases of
POST-MORTEM EXAM I ATIO
OF WILD BIRDS
33 1
TABLE II SEeo DARY LESIONS
Enteritis I Little owl, I Blackbird. Hepatosis and nephrosis I Black-headed gull, I Common gull , I Herring gull, I Scoter , 2 Guillemots. Hepatic infarct I Starling. Parasitic enteritis 3 Guillemots (Cosmocephalus sp.), 2 Gannets (nematode), I Starling (ces tode). Impacted cloaca I Guillemot (urates). Myco tic oesophagi tis 3 Guillemots. Ulcerated gizzard I Black-throated diver, 1 Great spotted woodpecker, 1 Mute swan. Pneumonia 1 Sparrow-hawk. Aspergilfosis (healed) 1 Scoter. Syngamus trachea 1 Crow. Visceral Gout 1 Starling. Arthritis I Guillemot, 1 Oyster-catcher, 1 Pheasant. Sepsis I Herring gull. Pan-ophthalmitis 1 Oyster-catcher, 1 Tawny owl. Trauma 1 Tawny owl, 1 Corncrake, 1 Blackbird. Abnormal Feathers 1 Rook, 1 Lapwing. Lice 1 Wood-pigeon (Coloceras sp.).
tuberculosis were found. The first was in a wood-pigeon with the typical dark plumage (McDiarmid, 1948 ) in which lesions were widely disseminated throughout the carcass and from which the typical avian strain of Mycobacterium avian was recovered. The second case was in a heron found dead in the grounds of a zoological garden at a time when avian tuberculosis was a problem in exhibited species. The heron could have had access to a number of pens were the disease was occurring. The post-mortem examination of the heron revealed a fusiform mass 9 cm x 2 cm of a uniform meaty texture in the position of the pancreas and, until histological examination revealed this to be of tuberculosis, it was considered to be a pancreatic neoplasm. A number of the cases of poisoning were of interest. Twelve sparrows were received out of a total of 32 found dead one morning in one room of a firm producing specialized metal castings and similar products. The room was large and airy with a number of opening sky-lights through which the sparrows were readily gaining access
332
BRITISH VETERINARY JOURNAL, 133,4
to the building, the evening before the deaths occurred the majority of the sky-lights were closed for the first time for several months. We were consulted to see if there was any risk to human beings but post-mortem examination of the birds revealed congestion and haemorrhage in the lungs of a non-specific type. We were later informed by the company that a process had been incorrectly set up to run over the night in question and considerable quantities of chlorine gas had been liberated . Eight sparrows were received for examination out of a total of 114 found dead after a corn crop had been sprayed by a helicopter but it was not possible to discover the nature of the agent sprayed. Similarly 12 starlings were considered to have been poisoned bu t the agent was not discovered. The birds were found dead over a small area of a recently sown field and the finder reported that the birds were 'unusually rigid and in peculiar positions' . There were no macroscopic lesions. In retrospect it is considered possible that this was mercury poisoning. A wood-pigeon was found in a town garden with clinical symptoms, prior to death, suggestive of a chloralose poisoning. This drug was being used to control feral pigeons in the area at the time. A magpie and a raven were found dead on open moorland close to the opened carcass of a rabbit which had obviously been shot. Analysis of the gizzard contents of both birds revealed large amounts of strychnine together with pieces of rabbit intestine. We were also involved with strychnine-injected hens eggs left on a public footpath, presumably with the object of poisoning crows. Two dogs ate one of the eggs and died and analysis of another egg revealed sufficient strychnine to kill approximately 20 people. The incidence of poisoned birds reported here is probably higher than its incidence in the avian population as a whole. The reasons for this are that mass deaths attract the interest more than individual deaths. Neoplasia was found in a tawny owl which had an anaplastic tumour of the tissues of the posterior part of the mouth, nares and upper part of oesophagus and larynx. Most authors agree that neoplasia is relatively uncommon in wild birds with th e exception of squamous papillomas of the feet of chaffinches (Blackmore & Keymer, 1969; Keymer & Blackmore, 1964). The examination post mortem of a black-throated diver revealed the presence of minute adrenal glands, about quarter the size of those in a bird of the same species which had been in captivity for three months following fracture of the wing. The author has seen similar atrophy of the adrenals of some species of birds in zoological gardens where the lesions were considered to be exhaustion atrophy following prolonged stress. A fledgling crow was considered to have died of shock; it fell out of the nest, being unable to fly due to a feather defect (vide infra), into a bowl of water, was immediately rescued but died three minutes later. A number of birds died of trauma, a proportion of these were almost certainly traffic accidents but as they were found away from the immediate vicinity of roads , they had presumably died a little while after being hit. A heron was found under some power lines, a gannet with extensive fractures of the skull was found at the base of a cliff, and a raven and an oyster-catcher had been shot. REFERENCES
(1970, 1971, 1972, 1973, 1974). lst, 2nd, Jrd, 4th and 5th Annual Reports of the Advisory Committee on Oil Pollution of the Sea, Research Unit on the Rehabilitation of Oiled Seabirds. Department of Zoology, University of Newcastle-upon-Tyne.
A NON,
POST-MORTEM EXAMINATION OF WILD BIRDS
333
BLAC KMORE, D. K. & KEYMER, I.F. ( 1969 ). Br. Birds, 62, 316. COOPER, J.E. ( 1972). Veterinary Aspects of Captive Birds of Prey, The Hawk Trust, Newent, Clo u cestershire . J EN NINGS, A . R . ( 1954 ).j. compo Path. 64,356 . JENNINGS, A. R. ( 196 I). Bird Study, 8, 25. KEYMER, I. F. (1958). Vet . Rec. 70, 713 and 736. KEYMER, I. F. (1972 ). Vet. Rec. 90,579 . KEYMER, I. F. & BLACKMO RE, D . K. (1964 ). Br. Birds, 57,157. MAC DIARMID, A. (I 948 ).}. compo Path. 58,128. MAC DIARMID, A . (J 962 ). Disease of Free Living Wild Animals. Rome: F.A.O. MAC DIARMID, A. (1965 ). Br. vet.}. 121,245 . M c DoNALD, J. W. ( 1962). Bird Study, 9, 147. Mc DONALD,]. w. (1963). Bird Study, 10,91. McDoNA LD,]. W . (1965 ). BirdStudy, 12, 181. M c DONALD, ]. W. & CORNELI US, L . W. (1969 ). Br. Birds, 62, 28. SAUNDE RS, H. E. et at. (196 I). Cited by McDonald,]. W. (1963). Bird Study, 10,91. WEIR, D . N. (J 97 I). Bird Study, 18, 147 . WOODFO RD, M. & CLASIER, P. E . B. (1955 ). Falconer, 3, 63.
(Acceptedfor publication 26 August 1976)
