Isle Royale has the most stable Common Loon population in Michigan, where, because of a declining population, it is formally listed as a Threatened Species. Park staff and researchers have been recording loon reproductive success within the park since 1990, both for the inland lake and Lake Superior waters. Isle Royale has the only known loon population that uses Great Lakes waters for nesting; the protected bays and islands around the park thus are critical habitat for these highly sensitive birds.

Loon reproduction was quite low in 1996 and 1997, when only 15 and 20 loon chicks, respectively, survived until August (and then presumably fledged). In 1998, with additional survey effort, we recorded 41 chicks that survived into August. More favorable spring weather in 1998 than the previous two years likely contributed to this healthy increase.

Ongoing monitoring is showing us how vulnerable loons are to human disturbance, however, especially during the critical nesting period (late April – early July). Loons will not tolerate humans coming close to their nests. Since 1997, we are aware of at least 3 situations where boating activity – both powerboats and paddlers - have contributed to the abandonment of nests or the loss of a chick because they passed too close to a nest or a family with young.

You will see additional loon protection information in campgrounds and visitor centers this summer, but in general stay at least 100 yards away from loons, particularly near their nesting and nursery locations along protected islands and shorelines. Don’t approach too close and don’t throw a wake in these areas. Loons will choose the protected sides of islands within bays for nesting – avoid these areas until early July.