Loons:

The order Gaviiformes consists of only 5 extant species of loon.  All of these living species are found in a single family (Gaviidae), in a single genus Gavia. 

The following is a list of all living species: 

• Red-throated Loon
• Black-throated Loon
• Pacific Loon
• Great Northern Loon
• Yellow-billed Loon