On its face, the photo is comical. A loon sits on its egg on a swim raft, a meter from an American flag. A garish McMansion is visible on the opposite shore. Few photos of the common loon are more at odds with the image of the species as a symbol of the northern wilderness. Yet Linda Grenzer’s photo of the nest on Crystal Lake is a poignant portrait of the situation faced by most territorial pairs in north-central Wisconsin.
Many popular accounts describe common loon populations as holding on for dear life. To be sure, loons are threatened by shoreline development, which reduces nesting habitat. Recreational fishing and boating kills many adults and chicks prematurely each year. And methylmercury in the food chain, swollen by coal-based power production, likely impacts the loon population as well.
Against all odds, however, loons appear to be holding their own in northern Wisconsin. Despite consistent losses caused by collisions with boats and entanglement in fishing lines, populations have bounced back in recent decades. The surprising resilience of loons seems to result from two facts. First, loons prefer to nest on small islands and on boggy and marshy habitats that humans avoid. Thus, loon pairs continue to produce young on lakes that are virtually encircled by human dwellings. Second, as illustrated in the photo, loons tolerate — and rarely even benefit from — human alterations of aquatic habitats.
The pair on Crystal Lake, whose nest is pictured, were in a real bind. Crystal is a very pleasant lake, but it lacks islands — the nesting spots most favored by loons — and also features neither bog nor marsh. Previous nesting attempts by the male (reared on nearby Muskellunge Lake in 2006) and a parade of 3 or more different females since 2011 ended in abject failure, the eggs an annual donation to local raccoons. Although they crawl onto it with great difficulty and complete loss of dignity, the Crystal pair decided a few weeks ago to place their nest on a low-lying swim raft. The raft is high above lake level and not equipped with any sort of ramp to assist small chicks in re-mounting the raft once they have entered the water, so we are concerned that the chicks will not be able to return to the nest (to be kept warm by a parent in the first few days of life) once they have left it. Still, the likelihood of hatch is good, and Linda and her helpers placed nesting material on the raft to keep the eggs from rolling off. We are hopeful that the loons can cope with the problem of nest height just as they do with a host of other anthropogenic obstacles each day in northern Wisconsin.
I shall keep you informed. If the Crystal pair can hatch and rear their chick to adulthood, they will be a vivid example of the capacity of loons to adapt and thrive in an environment thoroughly dominated by another species.