The Great Northern Loon (Gavia immer), is a large member of the loon, or diver, family of birds. The species is known as the Common Loon in North America and the Great Northern Diver in Eurasia; its current name is a compromise proposed by the International Ornithological Committee. The Great Northern Loon is one of the five loon species that make up the genus Gavia, the only genus of the family Gavidae and order Gaviiformes. Its closest relative is the other large black-headed species, the Yellow-billed Loon or White-billed Diver,Gavia adamsii. Wikipedia – http://en.wikipedia.org/wiki/Common_loon