Calliope Hummingbirds are tiny and have green upperparts. Males have red and white streaked throats, while females have dull whitish throats as well as whitish or cinnamon-buff chest and belly. Juveniles resemble adult females; in the hand, they can be distinguished from adult females by the presence of ridges along the upper mandible.

References cited in Species Profile

• Bent, A. C. 1940. Life Histories of North American cuckoos, goatsuckers, hummingbirds, and their allies. U.S. Natl. Mus. Bull. No. 176.
• Brunton, D. F., S. Andrews, and D. G. Paton. 1979. Nesting of the Calliope Hummingbird in Kananaskis Provincial Park, Alberta. Can. Field-Nat. 93:449-451.
• Calder, W. A. 1971. Temperature relationships and nesting of the Calliope Hummingbird.Condor 73:314-321.
• Calder, W. A. 1973. Microhabitat selection during nesting of hummingbirds in the Rocky Mountains. Ecology 54:127-134.
• Cornell Lab of Ornithology. 2015. Calliope Hummingbird. All About Birds. http://www.allaboutbirds.org/guide/Calliope_Hummingbird/id
• Dunning, Jr., J. B. 1993. Significant encounter. N. Am. Bird Bander 18:23-28.
• Great Basin Bird Observatory. 2015. Calliope Hummingbird. http://www.gbbo.org/pdf/bcp/52_Calliope%20Hummingbird.pdf
• Johnsgard, P. A. 1983. The hummingbirds of North America. Smithsonian Institution Press, Washington, D.C.
• Mailliard, J. W. 1921. Notes on the nesting of the Yosemite Fox Sparrow, Calliope Hummingbird, and Western Wood Pewee at Lake Tahoe, California. Condor 23:73-77.