Minnesota’s state bird—the common loon—is best known for its wailing call, which naturalist John Muir called “One of the wildest and most striking of all wilderness sounds.” Larger than a mallard duck and smaller than a Canada goose, the common loon’s distinctive breeding plumage is velvety black with a slight greenish gloss on the head and pure white on the underside. A striking white “string of pearls” graces its neck like a necklace. The plumage is acquired in a complete molt between January and March, which grounds the bird for nearly a month. Its winter plumage is somewhat duller, mostly grays and white.
Though most birds have hollow bones optimized for flight, loons have nearly solid bones optimized for diving as deep as 200 feet below the water’s surface in search of fish, frogs, leeches, crayfish and other prey. The extra weight means that they need a runway of over 100 feet to get airborne—as they paddle furiously across the water’s surface—but once aloft they can reach speeds in excess of 55 miles per hour.
Common loons breed throughout central and northeast Minnesota, usually building large, bulky nests at the water’s edge of clear, quiet lakes. The birds usually mate with the same partner each spring, their quiet courtship displays of simultaneous swimming, head posturing, and short dives serving mostly to renew their pair bonds. Clutches typically consist of 2 eggs, which incubate about 28-29 days. Chicks leave the nest within 24 hours, but adults carry them on their backs for the first 3 weeks and provide most of their food for the first 8 weeks. They begin to fly after 11-12 weeks and reach sexual maturity around age 2-3. Loons depart Minnesota for their Atlantic and Gulf coast wintering grounds in September.
Though common loons are protected by the federal Migratory Bird Treaty Act of 1918, they continue to face a number of threats. They are particularly vulnerable to human disturbances at their breeding lakes because harassed adults will abandon nests, sometimes for more than an hour, increasing the risk of nest predation by raccoons, crows, snapping turtles and other predators. Continued harassment can cause birds to move off a lake completely. Lakeshore development also impacts their breeding habitat, and mercury contamination is having a long-term impact on survival and reproductive success. Protection of prime habitat is the best conservation practice currently available.March 07, 2011