Causes of mortality in the Mute swan Cygnus olor on the River Thames
Article first published online: 20 AUG 2009
Journal of Zoology
Volume 198, Issue 1, pages 15–25, September 1982
How to Cite
Birkhead, M. (1982), Causes of mortality in the Mute swan Cygnus olor on the River Thames. Journal of Zoology, 198: 15–25. doi: 10.1111/j.1469-7998.1982.tb02057.x
- Issue published online: 20 AUG 2009
- Article first published online: 20 AUG 2009
- Accepted 28 January 1982
Over the last 20 years there has been an unprecedented decline of the Mute swan on the River Thames. Between August 1979 and October 1981 a systematic attempt was made to collect as many swan corpses as possible. Of 94 swan corpses examined at post-mortem 57% died from lead poisoning due to ingestion of anglers' weights. Birds dying from lead poisoning had significantly higher liver and kidney lead levels. Kidney proved to be the most useful indicator tissue, the median lead level in birds with lead weights in their gizzard was 908 μg/g DM compared to 8 μg/g DM in birds without weights. More immature birds die from lead poisoning than other factors and significantly more corpses were found between the months of July-October.
Ultra-structure examinations revealed electron dense intra-nuclear inclusions in the cells of proximal convulated tubules of the kidney and X-ray analysis confirmed that these structures consisted of lead.