Lead Toxicity in Mute Swans

Ringed Mute S1rans
?f the. 61 I r~~h-rin _ged ~irds r.eco~ered or controlled, 19 were ringed
as JUVemles . hve of the .1uve111lc birds were recovered or controlled
more than 50km from their ringing locations. The six British birds
recorded here were all ringed as juveniles. (A "juvenile" is a bird
known to be less than two years old. A swan's age is reckoned from )
July since most are hatched by then).
No swan could be confidently identified as an adult (at least three
years old) when ringed. However, nine bin.ls were known to be at least
two years old at ringing. Of these, six were recovered or controlled
within 20km of their ringing locations and the greatest recoverv
distance was 31 km. tvlinton ( 1971) found that most large movement;,
among a population studied by him in Britain, took place during the
first two years of a swan's life.
The recovery of a swan in Portarlington in April 1963, 155km away
from Lurgan where it had been ringed in January 1961, represents the
largest distance known to have been travelled by an Irish-ringed Mute
Swan within Ireland.
Life Expectancy
Forty ringed birds were found dead. Twelve of these (all juveniles)
\Vere of known age when ringed and hence their approximate lifespans
arc known . These are given in Table 2. Five had reached adulthood.
The oldest died at an age of approximately 4 years 9 months.
Tahll' 2. Sun·i\'al ol' Irish ~· .. 1utt: Swans ol' known agt:.
Age ar dearh 0 to I I to 2 2 to 3 3 to 4 4 lo 5 yt:ars
Numh