Lead Toxicity in Mute Swans

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I ' ABSTRACT The use of blood lead levels in assessing lead exposure in Mute swans Cygnus olor (Gmelin) is investigated. 823 blood samples were taken from 456 uniquely ringed Mute swans at a coarse-fish angling site over a period of 24 months. Blood lead values in individual swans monitored over several weeks were shown to conform to a recently reported kinetic model for blood lead values in birds. The highest median lead level for flock birds were recorded in the winter and spring and the lowest during the summer moulting period. The use of Free Red Blood Cell Protoporphyrin for detecting lead exposure was examined. Whole blood lead detected 44% (n=357) with elevated lead, while free red blood cell protoporphyrin detected 34.50%. In a large number of cases levels of protoporphyrin were above the normal level while the corresponding lead levels were low. The value of both methods and the need to correct each value for haemoglobin is discussed. - 13 -
I INTRODUCTION Lead poisoning due to ingestion and retention of shotgun pellets has been well documented in waterfowl. In the United States of America, it is a serious problem, with losses of up to two million ducks and geese each year from lead poisoning (Roscoe et al., 1979). During feeding, spent gunshot is ingested from the marshy bottoms of shallow waters in heavily hunted areas. Lead poisoning has also been recorded in upland game birds. (Reiser and Temple, 1981) and birds of prey (Wilcove and May, 1986). In Denmark and Ireland lead poisoning has been reported from areas of clay-pigeon shooting (Clausen and Wolstrup; 1979 and O'Halloran ~al., 1987a). Lead 'split shot' and 'ledger weights'used for fishing have caused mortality in Mute swans, Cygnus olor (Gm) [O'Halloran et al., (a) in press, Birkhead, 1982]. Post-mortem examinations may reveal lead poisoning in wildbird populations, but there is an increasing need to monitor the situation in live wild birds. Most prior investigations have involved the feeding of lead to live birds in the laboratory, but the validity of extrapolating these results to the natural environment has been questioned because of the contrasting pattern and duration of exposure to pollutants in the two situations (Hutton, 1980). Birkhead (1983) was one of the few workers to employ routine live bird assessment 'in the field'. Two methods are commonly employed in assessing the extent of lead poisoning in live birds: (1) measurement of whole blood lead and (2) measurement of free red blood cell protoporphyrin IX (FRBCP); birds have nucleated red blood cells, thus the term erythrocyte should not be used. The - rationale for blood lead assessment is clear: (a) blood lead is easily accessible for biopsy, (b) methods of analysis are well - 14 -
Page 2 and 3: 0004067t:.7 1~11111 /I llll II llll
Page 4 and 5: This thesis is dedicated to my moth
Page 6 and 7: ABSTRACT Lead toxicity in Mute swan
Page 8 and 9: - what are the best methods for the
Page 10 and 11: Benson, W.W., Brock, O.W., Gabrica,
Page 12 and 13: CHAPTER 1 DETERMINATION OF HAEMOGLO
Page 14 and 15: MATERIALS AND METHODS Blood was obt
Page 16 and 17: standards are now available, it is
Page 20 and 21: developed and (c) information on bl
Page 22 and 23: MATERIALS AND METHODS Study sites.
Page 24 and 25: Swans were sexed by cloacal examina
Page 26 and 27: Red blood cell protoporphyrin .. Th
Page 28 and 29: RESULTS Blood Lead Levels Diel vari
Page 30 and 31: 16.00 24.CO 2.00 7.00 - ~ ~--1_ J l
Page 32 and 33: for corrected lead values (ug /g Rb
Page 34 and 35: Table 2. Blood lead levels of indiv
Page 36 and 37: 30 20 (A) n = 357 10 0-.99 1- 2- 3-
Page 38 and 39: Blood lead is very labile (Chamberl
Page 40 and 41: median value of lead in April is si
Page 43 and 44: elevated lead levels. (2) Haemoglob
Page 45 and 46: Chisolm, J.J. & Browne, D.R. (1975)
Page 47 and 48: Ohi, G., Seki, H., Akiyama, K. & Ya
Page 49 and 50: CHAPTER 3: SECTION 1 LEAD POISONING
Page 51 and 52: mammals' (Finley et al. 1976). This
Page 53 and 54: commute from areas up to 20km away
Page 55 and 56: TABLE 1: Causes of death in Irish s
Page 57 and 58: I 4. Coiled shot: malleable stainle
Page 59 and 60: CHAPTER 3: SECTION 2 LEAD POISONING
Page 61 and 62: I INTRODUCTION The importance of le
Page 63 and 64: 42,000 anglers visit the State each
Page 65 and 66: MATERIALS AND METHODS Study sites B
Page 67 and 68: 30KM f Fig.l Map of Ireland indicat
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lead. X-ray. They were subsequently
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RESULTS Blood levels Blood lead lev
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I Table.II Proportion of lead poiso
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I of the gizzard and oesophagus and
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Table IV. 11 (of 41) X-rayed swans
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Table V. Median water lead levels (
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of pellets had occured. What is sig
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irds by Bellrose (1959) in the U.S.
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I the pellets as they moved in shor
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i Chamberlain, A.G. (1985). Predict
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Ong, C.N. & Lee, W.R. (1980). Inter
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SUMMARY Reference levels of some bi
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I adults, immatures, females and ma
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I centrifugation in microhaematocri
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RESULTS All blood samples included
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Table 1. Mean (± s.e.) maximum and
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Table 3. Haematological and biochem
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Table 5. Haemoglobin, haematocrit a
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Table 6. Age, sex, blood lead level
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DISCUSSION The normal range of haem
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considered when using protoporphyri
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I the blood constituents, reflectin
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REFERENCES Bates, F.Y., Barnes, D.M
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i Lucas, A.M. and Jamroz, C. (1961)
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CHAPTER 5 TISSUE LEAD LEVELS AND HA
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INTRODUCTION Lead poisoning through
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I r MATERIALS AND METHODS Collectio
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I RESULTS Tissue lead levels Tissue
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Table 1. Tissue lead levels (ug/ g)
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Table 3 Age, sex, blood lead level
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DISCUSSION Tissue lead levels have
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which had collided had raised blood
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REFERENCES Anders, E., Dietz, D.D.,
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O'Halloran, J., Myers, A.A. and Dug
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many others for helping to catch sw
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APPENDIX 1 LEAD LEVELS IN MUTE SWAN
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intense fishing in summer and large
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area of 4m 2 , were taken. The samp
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levels of the birds on the Lee also
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i oesophagus, proventriculus and gi
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in blood. In general, healthy birds
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toxic lea? l~vels. The post-mortem
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London area. Part 2 Biological Effe
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Prelin1inary results of ringing Mut
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Ringed Mute S1rans ?f the. 61 I r~~
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Acknowledgments Ringed Mute S1ra11s
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Lead Toxicity in Mute Swans

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