Lead Toxicity in Mute Swans

Swans were sexed by cloacal examination (Hochbaum, 1942) and age was
determined by plumage characteristics and beak colour.
Moulting birds were caught by herding the swans into a large netted
area.
Caging regime.
To determine if diel changes occured in haemoglobin and blood lead
it was neccessary to cage the swans for blood sampling.
Swans were
caged for 15hrs in separate pens, each measuring 3m X 4m, with peat moss
on the floor.
Crushed turkey feed, green vegetables and water were
freely available to the birds.
The sampling times for the eight swans sampled during the day was as
follows: 10.00, 12.00,and 16.30 hrs and at night from 16.00/16.30,
24.00, 02.00, 05.00 and 07.00 hrs. Two regimes were set up, depending
on the amount of light, (1) natural darkness from 16.00-07.00 hrs in
winter together with an artifical dark period 23.00-03.30 hrs. (2)
natural light cycle with short night period from 23.30-04.00 and an
artifical dark period from 16.30-07.00.
l.5ml of blood was taken for
haematocrit, haemoglobin and lead analyses.
Birds were released
following the sampling period.
Blood lead analyses.
Blood lead was estimated following a wet acid digestion.
400ul of
whole blood were digested using l.6mls of 10% nitric acid (Aristar
grade).
Specimens were spun in a Beckman bench centrifuge at 2,500 x g
(determined stroboscopically) and lOul of the supernatant was removed
and inject~d into graphite tube for analysis. Standard material was
prepared by adding known amounts of lead to a human blood pool.
The
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