The Common Loon may live twenty years or more. We think it has continued to grow and thrive A LOT since then. The estimated 15,000 loons in the Upper Great Lakes States of Minnesota, Wisconsin, and Michigan comprise nearly three-quarters of the loon population outside of Alaska. Research suggests that loon populations in Michigan and Wisconsin have rebounded from drastic declines earlier in this century, and the loon population in Minnesota is still thriving. But many threats remain.
Human activities are largely responsible for the disappearance of loons from many lakes.
Development of shorelines and islands for summer homes, campgrounds, and marinas has destroyed traditional nesting areas and other suitable sites. Disturbance of loons, especially during sensitive nesting and chick-rearing periods, can reduce or wipe out loon populations. Pollution of lakes used by nesting loons can lead to accumulations of toxins in eggs and young and the loss of food for chicks and adults. In 1978, the Sigurd Olson Environmental Institute initiated a loon-conservation program in Wisconsin, and later, a similar program in Minnesota. In 1988, these two loon projects merged into one program known as LoonWatch.