Survey of blood lead levels in trumpeter swans (Cygnus buccinator) in Ontario, Canada

Lead toxicosis in waterfowl has been well documented for a century, with the majority of studies analysed from carcasses of dead birds. Lead can remain in the environment for decades; the sublethal effects of lead remain unknown in the once extirpated trumpeter swan (Cygnus buccinator) population in Ontario, Canada. The purpose of this study was to survey healthy, free-ranging trumpeter swans in Ontario to determine blood lead levels. Blood samples from 95 trumpeter swans in Ontario, Canada, revealed lead levels above 3.2 µg/dL in 90% of the birds, with 30% of the swans having blood lead levels exceeding 15 µg/dL. Furthermore, 11 birds from the population were admitted to wildlife rehabilitation centres with suspected lead toxicosis, with blood lead levels as low as 13.5 µg/dL. Three of the 11 birds were chelated for lead toxicosis, whilst the remaining eight received supportive care. These data show that lead toxicosis, even at low blood lead levels, could be a concern for the health and welfare of trumpeter swans in Ontario and for the potentially damaging ecological effects of lead ingestion by other animals. The long-term effects on the health of swans sampled in this study remain unknown.