Invasive species may be key to understanding death of hundreds of loons by Dan Kraker , Minnesota Public Radio DULUTH, Minn. — Spring is in the air, with daylight savings taking effect on Sunday, and loons will begin their migration back to the north woods in less than a month. Loons, of course, are a cultural and natural icon, not only in Minnesota but across the Great Lakes states. But last fall, nearly 900 loons died while migrating south across Lake Michigan, probably more. And it's likely at least some were from Minnesota. Scientists are not sure what killed the loons, but they suspect that invasive species may be to blame. In October, Lynette Grimes was hiking toward Lake Michigan at Sleeping Bear Dunes National Lakeshore, outside Traverse City, Mich. The 52-year-old from the nearby town of Benzonia has walked the beaches there for y...