Lead Toxicity in Mute Swans

elevated lead was 11.00 (3.00 - 85 00 n = 13) f
· , or new coverts and
27.35 (4.40-90.00, n = 11) for old primary coverts . In birds with no
history of elevated lead values, levels were lower in the new feathers
(median = 6.50, 3.80-160.00, n = 12) and higher in old feathers (median
= 47.00, 38.00 - 67.40, n = 6).
Blood lead levels and changes
Lead levels, haemoglobin concentration, mean cell haemoglobin
concentration and haematocrit of three swans sampled before they were
involved in collisions are presented in Table 3.
Changes in
haemoglobin, haematocrit, mean cell haemoglobin and lead levels in
repeatedly sampled birds with elevated lead are given in Table 4.
X-ray examination of three birds revealed that elevated lead was due to
the ingestion of lead weights (Table 4).
One swan (specimen 1, Table
4) had a low blood lead level (2.80 ug/ gHb) though X-ray revealed a
lead weight to be present.
The blood lead level increased until day
116 when it began to drop. When subsequently X-rayed on day 130, the
lead weight was absent and the blood had returned to normal (Table 4).
Swans with high blood lead levels had low haemoglobin concentrations.
In specimen 2, the haemoglobin level did not drop for a time after the
highest blood lead value.
In many cases, the haemoglobin level dropped
below the reference limit for healthy swans~
but only in two cases did
the mean cell haemoglobin drop outside the reference limit (specimens 2
and 6).
As the lead level declined, the haemoglobin level began to
rise back to normal levels until about day 50, when it fully recovered
(Table 4).
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