Nearly 300 loons and other birds have been reported dead along the shores of Sleeping Bear Dunes National Lakeshore. The Detroit Free Press today reported that southwest and northwest winds in recent weeks caused the birds to wash ashore.
Botulism first surfaced as a major concern in Lake Michigan in 2006. Biologists explain the surge in botulism deaths this way: Zebra and quagga mussels filter plankton out of the water causing greater clarity. Sunlight is able to penetrate further and large mats of algae form on the lake bottom. As those mats decay they become depleted of oxygen and bacteria then thrives. The bacteria then accumulates in the mussels which filter the water.
Round gobies feed on those mussels in and around the algae mats and pick up the bacteria. Loons and other fish-eating birds, like cormorants, grebes and gulls pick up the gobies and get poisoned. Botulism affects the nervous system leaving the birds paralyzed. Scientists believe that many drown. Michigan’s oldest banded loon, The Patriarch, died as part of the mass die-off.
Read more: Avian Botulism