Gaviiformes is a bird order that comprises the loons. Apart from numerous extinct species, five species are placed in the genus Gavia:
- Red-throated Loon (G. stellata)
- Black-throated or Arctic Loon (G. arctica)
- Pacific Loon (G. pacifica)
- Common Loon (G. immer)
- Yellow-billed Loon (G. adamsii)
Hybrids within this group of birds are not common, but a few have been reported and described. McCarthy (2006) lists the following natural hybrids:
- Yellow-billed Loon x Common Loon
- Arctic Loon x Common Loon
- Common Loon x Pacific Loon
- Common Loon x Red-throated Loon
One study describes a hybrid between Yellow-billed Loon and Common Loon based on a museum specimen from the collections of the Zoological Museum Amsterdam (Roselaar et al. 2006).
McCarthy, E. M. (2006). Handbook of avian hybrids of the world. Oxford university press.
Roselaar, C. S., Prins, T. G., Aliabadian, M. & Nijman, V. (2006). Hybrids in divers (Gaviiformes). Journal of Ornithology 147, 24-30.