There are four species of loons, all of which live in the northern part of the Northern Hemisphere. The common loon, also called the great northern diver, is found during the summer on secluded lakes and rivers from the Northern United States to the Arctic Circle. It often spends the winter along coastal areas as far south as Texas. It is the state bird of Minnesota. Common loons measure about 30 inches (76 centimeters) long. Their backs and wings are black with white spots. The head and neck are glossy black and green, and the neck has white streaks. Their strange laughing calls echo over water and gave rise to the saying "crazy as a loon."

The yellow-billed loon looks much like the common loon but is somewhat larger. It lives only in the Far North. The arctic loon has a purple-black throat. The red-throated loon has an upturned bill and dull brown feathers, except for the throat.

Scientific classification. Loons belong to the loon family, Gaviidae. The common loon is Gavia immer. The yellow-billed loon is G. adamsii; the arctic loon, G. arctica; and the red-throated loon, G. stellata.