Early in the morning on Echo Lake, there’s a certain silence that feels off. The other kind, not the serene, pre-dawn kind. The kind you see when something that was once present just isn’t there anymore. The lack of a loon’s cry cuts in a way that is difficult to describe for anyone who has paddled these waters on Mount Desert Island in previous summers.
For as long as people can remember, the lakes in Acadia National Park have been home to the common loon. In search of fish, pairs return to the same areas every spring, carrying their young on their backs during the first few vulnerable weeks. The Mount Desert Island Loon Monitoring Project has been tracking nesting pairs here since 2002 by closely observing, cataloging territories, and banding individual birds. These birds are under pressure, and the forces driving them are greater than any one lake or season, according to the data, which is unsettling.
Common loon populations have been steadily declining throughout North America. According to data from the Breeding Birds Survey, the adult loon population in Canada decreased by almost 14% between 2005 and 2022. The figures are worse south of the border. Over a 27-year period, adult populations of loons in northern Wisconsin decreased by more than 20%, according to a long-term study. In the mid-2000s, the proportion of banded chicks that were later observed as adults was about 50%; today, it is about 10%. That is a slow-motion collapse rather than a gradual drift.
The core of this is climate change. Because loons only hunt by sight, heavier rainfall events are clouding lake water, which results in fewer fish being caught. As a result, loon chicks are becoming weaker and lighter than they were even ten years ago; on average, they are 11% lighter than they were in the early 2000s. The first five weeks of a chick’s life essentially determine its entire future, a phenomenon known as the “silver spoon effect” according to researchers. In that window, nutrition is not a developmental footnote, but a matter of life or death.
The tale of Lily and Herman, two banded loons on Echo Lake, illustrates some of the challenges these birds face. The pair had to move their nest several times due to declining water levels during drought years. Eggs were removed from nests by flooding seasons. The exposed shoreline was exploited by predators, especially mink. In the end, researchers set up a floating nest raft, which is a man-made platform that can rise and fall in response to water levels and sit securely away from predators on land. It seems Herman gave his approval. Every spring, he was known to leap onto the raft while workers were still setting it up.
The difficulties continue to grow despite such interventions. As water temperatures rise, mercury contamination in aquatic environments increases, building up through the food chain and concentrating in loons that feed at the top. In certain years, nesting adults are completely discouraged from laying eggs due to an increase in black fly populations, another effect of warmer, wetter springs. Chicks are disturbed at crucial stages by increased boat traffic. The vegetated edges that loons rely on are eliminated by shoreline development. The list is constantly expanding.
The loon’s condition is especially important because it serves as a sort of early warning system for the general health of the lake ecosystem. Reduced loon reproduction typically indicates a deeper issue, such as declining fish populations, shifting water chemistry, or stress on the entire web of life these lakes depend on. In this way, the loon is both a messenger and a victim.
In the upcoming decades, it is anticipated that the common loon’s breeding range will move considerably northward. This implies that the birds that have characterized the park’s lakes for generations may find a more suitable climate elsewhere in Maine and Acadia. For now, the math points to Canada. The window of opportunity to undo this seems to be smaller than most people think. Future tourists to Long Pond or Eagle Lake might wonder the same thing that people in Wisconsin and Minnesota are starting to wonder in private: where have all the crazy people gone? It’s probably time for anyone who is concerned about that sound at dawn to start asking.
