Why are hundreds of birds washing up on Michigan shore? Officials offer explanation

A “large number” of dead birds have been washing up along a Lake Michigan shore — and the National Park Service has offered an explanation.

Sleeping Bear Dunes National Lakeshore in Michigan said in a Facebook post Monday, Oct. 30, the birds began appearing on the shore the previous weekend.

Vince Cavalieri, a wildlife biologist for the national park, told WPBN it was “a surprise to see so many so quickly.”

“We are now over 400 just since Saturday in just the lake shore, which is a relatively high number for us and is our biggest outbreak in at least seven years,” Cavalieri told the station.

The casualties were largely made up of long-tailed ducks, but loons and mergansers have also turned up dead, Cavalieri told MLive.

So what is causing the outbreak?

Officials said the shorebirds likely died from type E avian botulism. Outbreaks of the illness have occurred in the area since at least the 1960s, park service officials said.

The U.S. Geological Survey calls botulism “one of the most potent toxins known to science.” The illness “interferes with muscle movements” and can lead to “weakness, lethargy (and an) inability to hold up the head or to fly.”

“For waterfowl, this can be catastrophic because inability to hold up the head leads to drowning,” officials said.

It’s caused when the birds ingest a toxic bacteria, according to Michigan State University. Typically, the bacteria does not harm wildlife, but it can become potent under certain conditions.

Outbreaks of type E avian botulism are most common in the fall months, Michigan State University specialists say.

Another outbreak occurred in November 2021, with some of the birds appearing on the shore without their heads — likely having been scavenged, according to the Leelanau Ticker.

While avian botulism does not affect humans, you’re advised to not touch any dead birds and to report them to the park, park service officials said.

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