Lead poisoning of waterfowl through the ingestion of spent gunshot and discarded anglers' weights continues to be a problem worldwide. We took blood samples from 363 whooper swans Cygnus cygnus at wintering sites in Britain and Ireland and at moulting sites in Iceland during 2001-2005, and analysed them for total blood lead. Lead levels were generally low in swans in Iceland; 6% of samples exceeded 1.21 mmol L À1 , the level indicative of elevated lead and above background levels. The proportion of swans with elevated lead was much higher in the wintering range, varying between 43 and 70% at three sites monitored over the winters 2003/2004-2005/2006, and with blood lead levels ranging up to 19.6 mmol L À1 . The highest levels were in samples taken from swans in Scotland, with a mean value of 3.0 mmol L À1 , but nevertheless they indicated a marked decrease compared with blood lead levels measured for whooper swans at the same site 20 years ago. There also appeared to be a significant long-term decrease in the proportion of swans with elevated blood lead in Iceland, from 60% of birds in 1984 to 8% in 2005, although this may be due to the birds being caught in different parts of Iceland. The most likely source of elevated lead in whooper swans is spent gunshot. Management measures to reduce the impact of lead in the environment on the birds are discussed.

Studies over two decades have shown a marked trend towards a decrease in blood lead levels in the mute swan (Cygnus olor) in parts of Ireland. However, this study shows that a small percentage of some populations of mute swans in Co. Cork still have significantly elevated lead levels, causing some potentially sublethal effects to the health status of the swans. Overall, at both urban and rural sites the median blood lead levels in adults and cygnets of both sexes were below a threshold level of 1.21mmol l (1 , which is indicative of elevated lead. However, 27% of the population at Cork Lough had elevated lead levels, with the highest blood lead level being 27.66mmol l (1 , indicating that acute poisoning is still a problem in some individuals. Mute swans from rural sites generally showed no variation, and median blood lead levels were generally low. Lead levels reached a peak in October 2004 and again during the spring months of 2005. Swans may be more susceptible to lead poisoning during spring, as it follows the winter months when natural food is scarce and lead is easily absorbed across the gut after ingestion. Autumn peaks may be explained by an increase in fishing activity over the summer months. A positive association was found between elevated lead levels and packed cell volume*an indicator of health status. Overall, a decline in acute lead poisoning at urban and rural sites is apparent from this study. However, due to its continued and persistent use in the environment, lead still poses a threat at a sublethal level.

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