Lead Toxicity in Mute Swans

I
Group (A) ten Mute swans with ingested anglers' pellets and with
kidney lead levels (range = 40.00-305.00 ug/g W.M.) and liver lead
levels (range = 170.50-450.00 ug/g W.M.) diagnostic of acute lead
poisoning.
Group (B) ten Mute swans and two Whooper swans with liver lead
(range = 18.00-550.00 ug/g W.M.) and kidney lead levels (range =
12.50-145.00 W.M.) exceeding the critical value diagnostic of lead
poisoning, which had no lead pellets in their gizzards, but tissue lead
levels and pathological findings which incriminated lead poisoning as
the cause of death.
Group (C) twenty Mute swans with low lead levels in kidney (range
0.40-19.00 W.M.) and liver (range = 1.00-14.00 W.M.) which had died
from causes other than lead poisoning (Table II).
Group (D) 49 Mute swans with shotgun pellets in their gizzards and
with high tissue lead levels.
kidney lead levels exceeded the criteria
for diagnosis of lead poisoning (range = 142.00-350.00ug/g W.M.) and
numbers of pellets varied from five to over 100 per bird (P.Cush, pers.
comm.).
In addition two Whooper swans that fell into this category had
kidney and liver lead levels that exceeded the values for diagnosis of
lead poisoning, being from 46.50 and 360.00ug/g W.M. and 30.00 and
800.00ug/g W.M. respectively.
Both birds had ingested gunshot in their
gizzards (one with seven and one with 25 pellets).
On the basis of diagnostic tissue lead levels, 68% of all Mute
swans examined were shown to have died from lead poisoning which was
thus the single largest cause of mortality.
Other causes of mortality
are shown in Table II. The pathological characteristics of lead
poisoned birds in this study agree with those of other workers (e.g.
Simpson, et al., 1979).
These included gross emaciation, impaction
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