Lead in the environment is a cause of concern for all living species. Lead leaches into water, corrodes our drinking pipes, is swallowed by fish that are food to eagles, and sinks into the soil where birds ingest it. Trumpeter Swans and other waterfowl eat vegetation that is growing on the bottom of lakes and rivers. This publication from the USGS National Wildlife Health Center gives us an overview of the problems caused by lead ammunition and fishing tackle, and this fact sheet from the Trumpeter Swan Society offers even more information.
Since 2012, we have discovered 10 swans and 2 Canada Geese that have died from lead poisoning. How do we know it was lead poisoning that killed the birds? As with any facility that holds wildlife, we send deceased animals to the DNR Wildlife Disease Lab for a necropsy (an autopsy for animals). The necropsies find lead fragments in the stomach contents of the animals, sometimes having up to 16 pieces in one bird. This xray shows a large lead fragment in the abdomen of a Trumpeter Swan treated at the MSU Small Animal Vet Clinic; this swan was found in Michigan.
There are alternatives to lead sinkers and bullets that are much friendlier to the environment. We encourage everyone to look into these safer solutions!