Lead Toxicity in Mute Swans

(Locke, Bagley and Irby 1966), those discovered in this study lacked
the characteristic fibrillar r:iargin found by Hutton (1980) to be
present after ~cute exposure m mammalian and avian species. (Goyer
et al 1971, Simpson et al 1979). However the number of inclusion
bodies in the nucleii is consistent with that found by Locke, Bagley
and Irby ( 1966) where two, three or four inclusions per nucleus were
present in Mallard Anas platrhyf!chus kidneys.
The effects of lead on birds varies according to the level of
exposure. Unfortunately most of the information collected to date has
been confined to fatal plumbism. However, the need to investigate
sub-lethal levels is urgently required. It is also desirable to strengthen
the monitoring technique, particularly by using zinc protoporphyrin
levels more widely. As far as Ireland is concerned it is now essential
to map the extent of the problem throughout the country. Only then
can the full implications of apparently rising levels of lead in our
environment and their potential effects on our wildlife be assessed.
Summary
Lead poisoning in Mute Swans Cygnus olor was studied for the first time in
Ireland. 104 swans were sampled at a coarse fishing site and 18 at other sites. Forty
one percent of birds at the coarse fishing site had blood lead levels greater than the
maximum tolerable limit of 40ug/ I OOmls. Only two birds at the other sites exceeded
this value. The first recorded fatality of an Irish Mute Swan due to lead poisoning is
described. The bird showed all the typical characteristics of the lead poisoning
syndrome.
Acknowledgements
We should like to thank Professor M. F. Mulcahy and Dr. Alan Myers for facilities,
assistance and supervision throughout this work; Dr. Tom Kelly for assistance and
critically reading an earlier manuscript; Clive Hutchinson and Ann-Marie Ryle for
their help; Mr. Joe Philpott and Robert McNamara for technical assistance.
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