Graceful in the air and terrific divers and swimmers, loons are clumsy on land, so they nest as close to water as possible, eliminating the need to walk where possible. Nests are built in hollowed-out mounds of dirt and the female may lay 1-3 eggs in it. Both parents work together to built the nest, incubate the eggs for about a month, and feed the hatchlings. The young chicks can fly in about 11 weeks. Loons are quite territorial and often only one pair will nest on a given lake or pond, unless it is quite large.
Loons have striking red eyes, black heads and necks, and white striping, checkering, and spotting on their backs. They grow up to three feet (91 centimeters) in length and weigh up to 12 pounds (5 kilograms). After breeding season, the bird loses this striking appearance and becomes brown with a white neck.
The Common Loon's dagger-like beak is perfectly adapted for underwater diving and it can dive to depths of 90 ft. Most loon dives last between 8.5 and 60 seconds. But under stress, loons can remain underwater for three minutes or longer.
During the winter months, loons are fairly quiet but during summer it becomes a noisy bird with quite an impressive range of sounds which many describe as 'haunting wailing', 'yodeling' or 'laughter'. When combined, these sounds are known as a 'tremolo' call and they can be quite overwhelming.
Loons live mainly on fish, such as pike, perch, sunfish, trout and bass, which it catches underwater in lakes. When near the sea, the bird tends to live on rock cod, flounders, herring and sea trout.