TRAVERSE CITY -- Botulism poisoning killed an estimated 7,500 native and migrating birds -- loons, ducks, gulls, cormorants and endangered piping plovers -- last year along the shorelines between Sleeping Bear National Lakeshore, the Straits of Mackinac and along the southern coast of the Upper Peninsula.
But among the scores of loons killed by botulism, it appears many originated from locales other than Michigan.
Researchers at Seney National Wildlife Refuge in the Upper Peninsula said only one banded loon did not return this spring to nesting grounds there. It was claimed by a botulism outbreak that's plagued northern Lake Michigan in recent years.
Experts point to the spread of invasive species in the Great Lakes as the culprit. But loon deaths may reveal some clues to migration and other patterns.
"This is just one site and we have a great interest in looking at where these birds came from," said Damon McCormick, biologist with Common Coast Research and Conservation.
One inference is that other loons killed by botulism had migrated from Canada or western parts of the Upper Peninsula when they became tainted with botulism toxins, he said.
An avian botulism task force among state wildlife officials, private researchers and a laundry list of nonprofit conservation groups will monitor this year's expected die-offs in early summer and autumn. Protocol for the count and collection of dead birds should be finalized by Memorial Day, said Tom Cooley, wildlife biologist with the Michigan Department of Natural Resources.
Meanwhile, dead birds found on area beaches this spring should be buried or taken to a landfill, officials said.
Beach cleaners should scoop up bird carcasses with a shovel and bury them on their own property, or collect them with rubber gloves or a garbage bag, Cooley said.
The bird deaths are likely a chain reaction from invasive species, including zebra and quagga mussels and round gobies, experts say.
Mussels filter the water, allowing more light to grow more cladophora algae, which hikes chances for botulism outbreaks. Birds can be poisoned and die by eating infected fish and mussels, as well as scavenging carcasses and maggots on the beach.
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