ROSE LAKE, Idaho (AP) — A grim death toll of migrating tundra swans is again being observed at northern Idaho marshes contaminated with toxic mining waste.
The swans headed for breeding grounds in Alaska stop at the marshes along the Coeur d'Alene River.
But the roots and tubers they feed on are laced with lead that's part of about 100 million tons of mining waste from the Silver Valley that has washed into the river system over the past century.
Lead shuts down the swans' digestive systems, and the birds slowly starve to death.
U.S. Fish and Wildlife Biologist Kate Healy says at least 150 of the large birds die each year as a result.
The U.S. Environmental Protection Agency is working to clean up the Coeur d'Alene Basin to make it safer for humans and wildlife.