Lead Toxicity in Mute Swans

42,000 anglers visit the State each year, of whom, 16,380 (39%) are
said to be coarse-fish anglers (Anon, 1986).
O'Halloran and Duggan
(1984) reported the death of a Mute swan from lead poisoning resulting
from the ingestion of anglers' weights in Co.Cork.
Because of the
seriousness of the problem in England it is essential to know the
prevalence of lead poisoning in swans in Ireland, but to date very
little research has been carried out on Mute swans.
There is a great
need to establish baseline information on the species, one of the most
susceptible to lead poisoning.
Little is known about what contribution contaminated grass in an
urban environment makes to acute lead poisoning in swans.
In the
present work, blood lead levels in a bird [Canada Geese Branta
canadensis (L)] which habitually grazes grass, were examined to see if
ingestion of lead contaminated grass resulted in an increased blood
lead levels and caused acute poisoning.
Some workers, (e.g. Birkhead, 1982), have suggested that boating
activities, particularly those which 'churn up' sediments, may cause
lead weights to be made more readily available to birds.
Careful
selection of sample sites is necessary to determine what contribution,
if any, urban lead makes to cause lead poisoning in swans.
Two methods are commonly employed to evaluate the level of lead
poisoning in animals (a) measurement of whole blood lead, which has
been useful in measuring lead levels in humans (Chamberlain, 1985) and
other animals including Mute swans (Birkhead, 1983) and (b) examination
of dead birds, which can provide conclusive evidence of lead poisoning.
In the present study, blood lead levels were examined in live Mute
swans fro~
different regions and these data were coupled with
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