Biological Exuberance: Animal Homosexuality and Natural Diversity

Courtship displays between female Raggiana’s Birds of Paradise involve some of the same postures and movements used in heterosexual courtship in this species. One female arches her wings above her back and then claps them against her sides, all the while bobbing up and down and erecting the feathers on her back and flanks as she dances in front of the other female. Every now and then she makes an ur, ur call, and she may even hang upside down on a branch while flicking her wings and calling. This dramatic pose is held for a minute or more at a time. Males use this inverted posture to show off their orange “tail” plumes during courtship, but females perform this display even though they do not have such ornate feathers. Sometimes two females engage in mutual display, facing each other while holding their wings stiffly above their backs and bobbing.

A male Victoria’s Riflebird courting another male with the “circular wings and gape” display

Frequency: Courtship displays between male Victoria’s Riflebirds occur fairly often at some times of the year, especially during the postmolting period in February and March. Although homosexual mountings are not common in this species, opposite-sex matings have in fact been seen only a few times during more than a hundred courtship displays observed in the wild.

Orientation: At least some male Victoria’s Riflebirds are functionally bisexual, courting and attempting to mate with both males and females. In Raggiana’s Bird of Paradise, courtship display between females has so far only been observed in captivity in the absence of males, so this behavior may be the expression of a potential or “latent” bisexual capacity. More detailed field observations and life histories are required, though, before any definitive statements can be made regarding the sexual orientation of individuals that engage in this activity.

Nonreproductive and Alternative Heterosexualities

Only about 11 percent of lek visits by female Raggiana’s Birds of Paradise actually result in heterosexual mating. More often than not, a courtship interaction is broken off by a female before copulation occurs. In addition, males often chase females and behave aggressively toward them on the lek, which deters them from participating in sexual interactions. When mating does take place, the female often mounts the male prior to copulation. Such REVERSE mounts are then followed by a display in which the male appears to pummel his partner with his wing. The female crouches on her perch absorbing the blows for 20—35 seconds, after which copulation occurs. Nonreproductive matings also take place outside of the breeding season. Many males may delay breeding up to five or more years once becoming sexually mature, since they do not generally acquire their ornate plumage (used in courtship displays) for several years.

Other Species

Male Greater Birds of Paradise (Paradisaea apoda), a species closely related to Raggiana’s, also sometimes court and mount younger males.

Sources

* asterisked references discuss homosexuality/transgender

Beehler, B.M. (1989) “The Birds of Paradise.” Scientific American 261(6):116–23.

———(1988) “Lek Behavior of the Raggiana Bird of Paradise.” National Geographic Research 4:343–58.

*Bourke, P. A., and A. F. Austin (1947) “The Atherton Tablelands and Its Avifauna.” Emu 47:87–116.

Davis, W. E., Jr., and B. M. Beehler (1994) “Nesting Behavior of a Raggiana Bird of Paradise.” Wilson Bulletin 106:522–30.

*Frith, C. B. (1997) Personal communication.

———(1981) “Displays of Count Raggi’s Bird-of-Paradise Paradisaea raggiana and Congeneric Species.” Emu 81:193–201.

*Frith, C. B., and W. T. Cooper (1996) “Courtship Display and Mating of Victoria’s Riflebird Ptiloris victoriae with Notes on the Courtship Displays of Congeneric Species.” Emu 96:102–13.

Frith, C. B., and D. W. Frith (1995) “Notes on the Nesting Biology and Diet of Victoria’s Riflebird Ptiloris victoriae.” Emu 95:162–74.

Gilliard, E. T. (1969) “Queen Victoria Rifle Bird” and “Count Raggi’s Bird of Paradise.” In Birds of Paradise and Bower Birds, pp. 112–17,222–29. Garden City, N.Y.: Natural History Press.

Lecroy, M. (1981) “The Genus Paradisaea—Display and Evolution.” American Museum Novitates 2714:1–52.

*Mackay, M. (1981) “Display Behavior by Female Birds of Paradise in Captivity.” Newsletter of the Papua New Guinea Bird Society 185/186 (November-December):5.