Loons or divers are a group of aquatic birds found in much of North America and northern Eurasia. All living species of loons are members of the genus Gavia, family Gaviidae and order Gaviiformes.
Loon
1918 illustration of a variety of loons by Archibald Thorburn. Top: Common loon, Mid-left: red-throated loon, Mid-right: yellow-billed loon, Bottom: black-throated loon
Common loon (Gavia immer) rearing up. Note the plump body and pointed but rather short wings
Yellow-billed loon (Gavia adamsii) in winter plumage
Gaviiformes is an order of aquatic birds containing the loons or divers and their closest extinct relatives. Modern gaviiformes are found in many parts of North America and northern Eurasia, though prehistoric species were more widespread.
Gaviiformes
Red-throated loon (G. stellata), the smallest living Gavia species. Some Miocene members of this genus were smaller still.