Lead Toxicity in Mute Swans

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Swans addition, birds are fitted with coded rings for individual recognition and to determine the extent of movement within the country. Knowledge of movements should prove to be of considerable use in evaluating birds as biological indicators of pollution, and in determining a focus of contamination. Where possible, live birds have been X-rayed to determine if ingested lead shot is present. Lead is a ubiquitous element and although lead shot, either from anglers' weights (Birkhead 1982) or from hunters' gunshot cartridges, is commonly regarded as a direct contaminant, it should be realised that background levels of lead vary considerably and probably contribute to elevated levels in birds. Environmental lead, particularly from vehicle exhaust, undoubtedly increases blood lead levels in urban populations of birds. Fifty per cent of birds sampled at Cork City Lough, for example, had between 0-2µ.moles Pb/L, equivalent to 40µ.gl lOOmL (cf. levels in humans: see paper by M. Murphy, this volume) (Fig. 1), which probably reflects background levels of lead in the environment. It should be borne in mine, however, that the swan community of the laugh is composed, on the one hand, of a mainly urban group and, on the other hand, of an immigrant component originating in a wide range of rural sites. Many rural birds have less than 1 µ.mole Pb/L of blood, while urban birds range from 1-2µ.moles Pb/L. Whilst the number of samples taken elsewhere (Dublin, Shannon and Killarney) is small, a trend of low values of lead is apparent (Fig. 1). These examples illustrate that environmental lead is present in varying degrees and the total amount varies from location to location. In the present work. Cork City Lough was chosen as the main sampling site. The laugh is a small shallow freshwater lake located in the western suburbs of Cork city about 7.5 ha (15 acres) in size. It is one of the most famous coarse fishing areas in the country and the risk from discarded anglers' weights is considerable. In addition, spent gunshot, from shooting during the early part of this century, must also be considered as a possible source of lead contamination. Owing to artificial feeding by man, a large flock of mute swans (up to 200) visit and feed in the area. These birds are at high risk from lead poisoning. It is generally considered that birds with greater than 2.0µ.moles of Pb/L blood have been contaminated by excess lead (Birkhead 1983), and this criterion is used here. On the same basis, more than 50% of birds sampled at the lo ugh have elevated bk>ad lead levels. However, because of the mobility of the lough's swan flock, a focus of contamination is difficult to determine. O'Halloran and Collins (1985), for example, have shown that 30% of ringed swans travel over 30km. Current results show that birds of the laugh move a considerable distance and frequently 47
commute from areas up to 20km away (Fig. 2). The recovery of a bird at the lough which had been ringed in Dublin 10 months earlier demonstrates this. The problem of determining a source of contamination is compounded by the fact that regular benthic sampling techniques are inadequate for surveying areas like the laugh. A standard sampling grab will sample mud 6 .. 8 0-1 2 2 3 "' 2 CORK 100 0-1 2 3 °' a a: (ij u. 0 0 z 50 Pb CONCENTFIATION FIGURE 1: The recorded blood lead levels in Irish mute swans from various locations. The blood lead !eves are in µmoles per litre. - 48 - I
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 18 and 19: I ' ABSTRACT The use of blood lead
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: mammals' (Finley et al. 1976). This
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
Page 69 and 70: lead. X-ray. They were subsequently
Page 71 and 72: RESULTS Blood levels Blood lead lev
Page 73 and 74: I Table.II Proportion of lead poiso
Page 75 and 76: I of the gizzard and oesophagus and
Page 77 and 78: Table IV. 11 (of 41) X-rayed swans
Page 79 and 80: Table V. Median water lead levels (
Page 81 and 82: of pellets had occured. What is sig
Page 83 and 84: irds by Bellrose (1959) in the U.S.
Page 85 and 86: I the pellets as they moved in shor
Page 87 and 88: i Chamberlain, A.G. (1985). Predict
Page 89 and 90: Ong, C.N. & Lee, W.R. (1980). Inter
Page 91 and 92: SUMMARY Reference levels of some bi
Page 93 and 94: I adults, immatures, females and ma
Page 95 and 96: I centrifugation in microhaematocri
Page 97 and 98: RESULTS All blood samples included
Page 99 and 100: Table 1. Mean (± s.e.) maximum and
Page 101 and 102: Table 3. Haematological and biochem
Page 103 and 104:
Table 5. Haemoglobin, haematocrit a
Page 105 and 106:
Table 6. Age, sex, blood lead level
Page 107 and 108:
DISCUSSION The normal range of haem
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considered when using protoporphyri
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I the blood constituents, reflectin
Page 113 and 114:
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
Page 119 and 120:
INTRODUCTION Lead poisoning through
Page 121 and 122:
I r MATERIALS AND METHODS Collectio
Page 123 and 124:
I RESULTS Tissue lead levels Tissue
Page 125 and 126:
Table 1. Tissue lead levels (ug/ g)
Page 127 and 128:
Table 3 Age, sex, blood lead level
Page 129 and 130:
DISCUSSION Tissue lead levels have
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which had collided had raised blood
Page 133 and 134:
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
Page 139 and 140:
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
Page 153 and 154:
London area. Part 2 Biological Effe
Page 155 and 156:
Prelin1inary results of ringing Mut
Page 157 and 158:
Ringed Mute S1rans ?f the. 61 I r~~
Page 159:
Acknowledgments Ringed Mute S1ra11s
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Lead Toxicity in Mute Swans

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