Biological Exuberance: Animal Homosexuality and Natural Diversity

Orientation: In Long-tailed Hermit Hummingbirds, approximately 7 percent of territorial males and 11 percent of all males participate in homosexual activity. Territorial males in both of these hummingbird species are probably bisexual, pursuing, courting, and mounting both females and males. Some of the male Long-tailed Hermits who visit other males’ territories are nonbreeders (they do not have their own territories), which means they probably do not participate in any heterosexual activity (at least for the duration of that breeding season). Male Anna’s Hummingbirds usually strongly resist being mounted by other males, perhaps indicating a more heterosexual orientation on their part (although females also sometimes resist heterosexual mating attempts).

Nonreproductive and Alternative Heterosexualities

Heterosexual mating in Anna’s Hummingbirds can have all of the aggressive and even violent characteristics described above for homosexual matings—males pursue females in high-speed chases and sometimes even strike them in midair, forcing them down in order to copulate. Some matings are also nonreproductive since they take place outside of the breeding season. Males in this species have their own distinct seasonal sexual cycle, with their sperm production and hormone levels greatly reduced from July through November. Male Anna’s Hummingbirds also frequently court females of other species such as the Allen hummingbird (Selas-phorus sasin) and Costa’s hummingbird (Calypte costae). Among Long-tailed Hermit Hummingbirds (as well as other species of hermit hummingbirds), males often “masturbate” by mounting and copulating with small, inanimate objects (including leaves suspended in spiderwebs).

Other than when mating, however, males and females in both of these species rarely meet. In Anna’s Hummingbirds, the two sexes occupy distinct habitats during the breeding season—males frequent open areas such as hill slopes or the sides of canyons, females occupy more covered, forested areas. Each female Long-tailed Hermit usually encounters males only once every two to four weeks when she visits the lekking areas prior to nesting. Males of both species take no part in nesting or raising of young. In addition, a significant number of birds are nonbreeders: nearly a quarter of all Long-tailed Hermit males are nonterritorial and therefore do not participate in heterosexual courtship or copulation, while of those who hold territories, only some get to mate with females.

Sources

*asterisked references discuss homosexuality/transgender

Gohier, F., and N. Simmons-Christie (1986) “Portrait of Anna’s Hummingbird.” Animal Kingdom 89:30–33.

Hamilton, W. J., III (1965) “Sun-Oriented Display of the Anna’s Hummingbird.” Wilson Bulletin 77:38–44.

*Johnsgard, P. A. (1997) “Long-tailed Hermit” and “Anna Hummingbird.” In The Hummingbirds of North America, 2nd ed., pp. 65–69, 195–99. Washington, D.C.: Smithsonian Institution Press.

Ortiz-Crespo, F. I. (1972) “A New Method to Separate Immature and Adult Hummingbirds.” Auk 89:851–57.

Russell, S. M. (1996) “Anna’s Hummingbird (Calypte anna).” In A. Poole and F. Gill, eds., The Birds of North America: Life Histories for the 21st Century, no. 226. Philadelphia: Academy of Natural Sciences; Washington, D.C.: American Ornithologists’ Union.

Snow, B. K. (1974) “Lek Behavior and Breeding of Guy’s Hermit Hummingbird Phaethornis guy.” Ibis 116:278–97.

———(1973) “The Behavior and Ecology of Hermit Hummingbirds in the Kanaku Mountains, Guyana.” Wilson Bulletin 85:163–77.

Stiles, F. G. (1983) “Phaethornis superciliosus.” In D. H. Janzen, ed., Costa Rican Natural History, pp. 597–599. Chicago: University of Chicago Press.

*———(1982) “Aggressive and Courtship Displays of the Male Anna’s Hummingbird.” Condor 84:208–25.

*Stiles, E G., and L. L. Wolf (1979) Ecology and Evolution of Lek Mating Behavior in the Long-tailed Hermit Hummingbird. Ornithological Monographs no. 27. Washington, D.C.: American Ornithologists’ Union.

Tyrell, E. Q., and R. A. Tyrell (1985) Hummingbirds: Their Life and Behavior. New York: Crown Publishers.

Wells, S., and L. F. Baptista (1979) “Displays and Morphology of an Anna X Allen Hummingbird Hybrid.” Wilson Bulletin 91:524–32.

Wells, S., L. E Baptista, S. F. Bailey, and H. M. Horblit (1996) “Age and Sex Determination in Anna’s Hummingbird by Means of Tail Pattern.” Western Birds 27:204–6.