Migration and Flight

Every fall, as the days turn cooler, and then downright cold and crisp, the most common and intriguing question posed to BRI’s Adirondack Center for Loon Conservation is: “Where do the loons go?” Throughout October, adult loons lose their black and white breeding feathers, replacing them with dull gray plumage. By late October, it becomes difficult to tell the adult and juvenile birds apart--their plumage is so similar. As the days pass, it is apparent that the birds are coming and going more frequently. Sometimes there are no birds observed on a lake, while at other times, there are more than usual.

By Thanksgiving, loons are rarely seen on Adirondack lakes, except for a few stragglers observed during a warm fall. Sometimes, a lone gray juvenile can be seen in late November on a small pond fringed with ice, only to leave the next day. Often, when a storm comes through, people report seeing more than a hundred loons feeding together in driving sleet on a large lake.

As winter approaches, the skies become gray and dreary and skim ice appears on the edges of the lakes. Some nights, the temperature drops well below freezing, hoarfrost coats the trees, and the smaller lakes freeze solid. Then the echoes of loon wails no longer resound off the Adirondack Mountains. Where do these birds go?

Although Common Loons breed in the Adirondack Park during the summer, they also spend from 5 to 7 months each year (October/November – April/May) along the Atlantic coast. Migration and wintering on the ocean are very stressful for these birds. In the fall, prior to migration, they molt their body feathers and grow their gray winter plumage. A significant amount of energy is expended during migration, since they must fly continuously for hours (they are not capable of soaring like a vulture or hawk) until they get to a “stopover” lake or the coast itself.

Once they arrive at their oceanic wintering area, loons change their diet from freshwater fish, crayfish, and invertebrates to saltwater prey. They must also activate their salt glands to expel the salt they take in while feeding and living on the ocean. In the winter, loons experience a complete molt, losing both their body and their wing feathers for a one month period and subsequently re-grow their breeding black and white plumage. During this period, they are flightless until their wing feathers re-grow, and they utilize much needed stores of energy to grow their new plumage.

Loons are also exposed to a variety of potential threats, such as oil spills, commercial fishing nets, and coastal storms during migration and on their wintering areas on the coast.