Great Lakes waterfowl, including the common loon, are undergoing significant die offs during their annual fall migration which could lead to serious population problems in the future. 
“According to the United States Geological Survey (USGS), there are about 30,000 common loons in the United States. During the breeding season, from early spring to late fall, about half of them reside in the Great Lakes’ states of Michigan, Wisconsin and Minnesota.
In 2012, thousands of dead birds, mainly common loons washed up dead on Lake Michigan shorelines – from the Upper Peninsula, down to the Sleeping Bear Dunes National Lakeshore. A large percentage of the dead loons had just entered their first year of breeding maturity. While the mortality rate in 2012 was the worst on recent record, it followed similar incidents that took place in 2006, 2007 and 2010. Northern Lake Michigan serves as a staging area for common loons from the Great Lakes states and Canada to load up on food before flying down to their wintering grounds in the Gulf of Mexico and the southern Atlantic Ocean.”
While the numbers are not as bad this year, the trend remains alarming. Read the complete article at the link above.