Lead Toxicity in Mute Swans

Each sarnp~ed bird was dye marked using three dyes; Malachite
~reen, Eosm and Gentian Blue. The purpose of dye marking the
btrds was two-fold, firstly to prevent resampling of the
. d' 'd 1 d di . same
m 1v1 ua an secon y to see if movement of birds occurred betw
l. . Th d een
samp mg sites. e yes were applied with a brush to the plumage of
the birds before release.
Age was determined by plumage characteristics and beak colour
Two-millimetre blood samples were taken from the brachial vei~
using a 23g l" syringe and stored in low lead heparinised tubes.
Blood lead concentrations were determined on a Pye unicam SP 192
atomic absorption spectrophotometer with a flameless atomiser
attachment and with a wavelength of 2 l 7nm. I 0% nitric acid
(proanalar grade) was used for digestion. All blood lead levels are
presented in µg/lOOmls of blood.
B. Post Mortem Examination
Two corpses were available for post mortem, one of a moribund
bird and the other of a cygnet killed in a collision with a high tension
electric cable.
The birds were dissected and their pathological condition recorded.
Blood samples were removed from the heart using the above
mentioned syringes. The kidney was removed from the moribund bird
and prepared for electron-microscope examination using standard
methods. Sections of breast muscle, kidney, liver and pancreas were
removed, weighed and stored at -30°C for tissue analysis. The liver
was weighed without gall bladder. The oesophagus, proventriculus
and gizzard were removed for examination.
Since the cygnet suffered multiple fractures in the accident, the
heart was the only tissue to be weighed. Nevertheless, sections of liver
and breast muscle were taken for tissue analysis. The oesophagus,
proventriculus and gizzard were removed for examination. The
contents of the alimentary canal were washed into a glass dish and
sieved through 2.8mm and 1.4mm sieves. The sieves were then
examined for spent lead shot. The linings of the gizzard were
examined and both were weighed.
C. Lead In the Environment
In order to try and establish the source of increas~d lead
contamination the bed of the main sampling site was exammed for
discarded lead' weights and the water of The Lough was examined for
elevated lead levels.
The bed of The Lough was examined using two methods.
( 1) A bottom grab sampler was dropped from a boat at .11 randomly
selected stations. A total of 200 grab samples, oovermg a surface
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