Dead trumpeter swans found at Sucker Lake in Vadnais Heights earlier this month died of lead poisoning, according to a University of Minnesota diagnostic lab report.

Members of the Vadnais Lake Area Water Management Organization (VLAWMO), who investigated the swan deaths, originally thought the swans had died of malnutrition.

“The results are lead toxicity likely from fishing sinkers that accumulate in the sediment,” said Dawn Tanner, program development coordinator with VLAWMO.

The Minnesota Department of Natural Resources estimates that 40 percent of Minnesota trumpeter swan deaths are caused by lead poisoning.

“Swans use their long necks to move the substrate around looking for pebbles that are the right size for their gizzard,” Tanner said. “Lead shot and sinkers are just the right size for gizzard stones.”

Unlike pebbles, shots and sinkers are soft, so instead of passing through the bird in a solid chunk, the lead is ground up in the gizzard and incorporated into the tissues.

“This was the result we anticipated,” said Tami Vogel, communications director for the Wildlife Rehabilitation Center of Minnesota. “We see dozens of animals every year, including swans, with lead toxicity. One pellet is all it takes to kill an adult trumpeter swan. Our new studies are showing lead in animals you would not suspect — opossums, squirrels, etc. It’s everywhere, and it’s toxic.”

Some of the lead is eaten by scavengers, like coyotes, who eat the dead swans.

A bird with lead poisoning will have physical and behavioral changes, including loss of balance, gasping, tremors, and impaired ability to fly. The weakened bird is more vulnerable to predators, or it may have trouble feeding, mating, nesting, and caring for its young. It becomes emaciated and often dies within two to three weeks after eating the lead, according to the Minnesota Pollution Control Agency.

Initial reports from around the state show approximately 27 dead swans were found this winter. How many died from lead poisoning is unknown.

About 10 dead swans were found at Sucker Channel, six at Peltier Dam in Lino Lakes, five at Pickerel Lake in Lilydale, four at Grass Lake in Stearns County, and at least two were found in Little Pine Lake in Ottertail County.

Swans will stay in Minnesota in the winter if there is open water. Parts of Sucker Lake stay open year-round due to aerators in the lake that keep it from freezing. Sucker Lake drains into East Lake Vadnais and is pumped to the St. Paul Regional Water Service’s treatment plant to process for drinking water. It’s also a popular spot for fishing.

Tanner counted at least 50 trumpeter swans swimming on the lake and in the channel in March.

Lead poisoning has been an ongoing issue for conservationists in the state.

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To mask or not to mask at MN polling places. Judge hears arguments. Legislators have considered banning lead sinkers in the past, but decided the better course of action would be to educate the public on the dangers and let the market drive the change as they sought non-lead alternatives.

Tanner hasn’t given up on the ban. She said she’ll be bringing it up again at the Minnesota Water Action Day April 1 at the Capitol.

“Once lead is in a lake or stream, it sits on the bottom and has the potential to do damage for a long time,” she said.