Wildlife biologists in Minnesota report the estimated number of waterfowl dying from eating lethal parasites on Lake Winnibigoshish since Oct. 28 has likely doubled to around 6,000 birds, making it the state’s worst such die-off on record.

And Minnesota DNR experts offer a gloomy outlook for thousands of additional waterfowl expected to use the lake as a migration stopover in coming weeks, with an increasing number of ducks possibly dying before the lake freezes.
Chris Niskanen, outdoors editor for the St. Paul Pioneer-Press, posted an update on the newspaper’s Web site yesterday evening. He writes that an additional 10,000 lesser scaup (bluebills) are currently rafted on the lake, and many more could arrive from Canada as cold weather pushes northern flocks southward.

Last year, Lake Winnibigoshish didn’t freeze until early December.

As of yesterday, biologists believe somewhere between 5,000 and 6,000 waterfowl have died from ingesting non-native banded mystery snails that are hosts to deadly parasites known as trematodes. The invasive snail species, which is popular among aquarium hobbyists, was first discovered in the lake eight years ago.
The ducks thus far succumbing to the trematode parasite have been bluebills, a diving species that feeds on mollusks. Hundreds of coots, also a diving waterfowl, were also found dead.

“I’m resilient to seeing dead ducks, but it’s gruesome to see them laid out like that along the shore,” Steve Cordts, MDNR waterfowl specialist, told Niskanen yesterday.

Cordts said DNR biologists considered hazing the birds with boats or shooting, but he noted the vast, 58,500-acre lake can be risky for boaters this time of year.

“We boated through a raft, but the birds flew right back to the spot,” Cordts said. “My guess is there is a huge density of snails out there. It’s like sucking them in with a huge pile of corn.”

Unfortunately, biologists—and waterfowlers to the south—can do little but watch helplessly as the duck death toll in northern Minnesota continues to rise.

“I have no idea how many we’ll lose,” said Cordts.