Loon, a large waterbird. It nests in the northern parts of the Northern Hemisphere and winters south to Florida and the Mediterranean, chiefly at sea. The loon has a straight, heavy, pointed bill; a moderately long, thick, snaky neck; a short tail; and short, slender, pointed wings. The three front toes of each foot are webbed; the short hind toe is free.The loon is noted for its wild, throbbing cry.
The hind legs are set so far to the rear that the loon can travel on land only by pushing its breast along the ground. It cannot take flight from land, and in taking off from water, the loon must take a pattering run across the surface. A deep diver, the loon has been caught in fishermen's nets 200 feet (60 m) below the surface. Using both feet and wings, it swims underwater fast enough to catch fish, its chief food. The loon makes a nest of plant matter and mud at the edge of a lake or stream. It usually lays two brown or olive-brown eggs blotched with darker colors.
The common loon grows about 32 inches (81 cm) long. It has a glossy black head and neck, and white underparts. A band of white streaks marks its throat and each side of its neck. Its back is marked with white squares, and its sides are white-spotted. The bird is noted for its wild, throbbing musical cry, which to some persons suggests insane laughter. In North America, the common loon nests from northern Canada to the northern United States.
The arctic loon nests in the treeless tundra, and is seen as far south as California in winter. It is about 24 inches (61 cm) long when mature. It has a black throat and lengthwise streaks of black at the sides of its neck. Two rows of oblong white patches mark each side of its back.
The red-throated loon grows about 25 inches (64 cm) long. It is generally grayish, with a rusty throat patch. In North America, it breeds throughout most of Canada and winters south to Florida and Lower California.
Loons have loud calls. Their calls sound like strange laughter. A loon is a large, heavy bird that weighs about 9 pounds (4 kilograms). Its legs are so far back on its body that it has trouble walking. When a loon does walk, it seems to crawl on its belly. But having feet so far back helps a loon to swim and dive. Loons can swim underwater and can dive down to depths over 150 feet (45 meters).
Loons use their long, narrow bills to catch fish. They also use their bills to defend themselves. Loons are pretty tough. Just ask a fox or a young bear. Loons sometimes frighten off their enemies by striking with their sharp bills. Other times, loons sink down below the surface of the water to avoid danger.
Loons belong to the family Gaviidae. The common loon is Gavia immer; arctic, G. arctica; red-throated, G. stellata.