Biological Exuberance: Animal Homosexuality and Natural Diversity

SWIVEL DISPLAYS: he hops and twists around his perch, approaching the object of his attentions with ruffled plumage and a rattling call—a continuous stream of notes that sounds like zik-zik-zik. No homosexual copulations have been observed in this species in the wild, but heterosexual matings are not commonly seen either. In captivity Orange Bishop Birds—both adults and younger males—sometimes do try to mount younger males (including males of the closely related Golden Bishop Bird, Euplectes afer). In a homosexual encounter, one male approaches the other while pumping his body up and down and ruffling his feathers, followed by an attempt to copulate with the other male (who usually rejects his advances).

A male Red Bishop Bird displaying fluffed “bumblebee” plumage, used during courtships with same- and opposite-sex partners

Frequency: In Sociable Weavers studied in captivity, as much as three-quarters of all mounting activity is between males, and three out of five full copulations are homosexual. The occurrence of same-sex mounting in wild birds of this species is not known, but its prevalence is probably comparable (especially since heterosexual activity is also apparently infrequent). In one study of wild Gray-capped Social Weavers, all sexual activity that was observed took place between males. In Red Bishops, approximately 6 percent of courtship bumble-flights are directed by one adult male toward another adult male; courtship of younger males probably occurs more often than this.

Orientation: Male Gray-capped Social Weavers that copulate with other males also mate and pair with females (and in fact may engage in homosexual activity while they are heterosexually paired). The same is true for some Sociable Weavers, although most males in this species mount both males and females, even if they are not paired. However, relatively few males participate in full heterosexual copulations, and those that do appear to have higher rates of homosexual activity as well. To the extent that they court or attempt to mount both males and females, some male Bishops are also bisexual. However, the males they pursue are usually indifferent, at best, to their approaches, indicating perhaps a more heterosexual orientation on their part.

Nonreproductive and Alternative Heterosexualities

In Gray-capped Social Weavers (and occasionally in Sociable Weavers), nonbreeding birds often help heterosexual pairs build their nest and feed their young. Some of these “helpers” are the pairs’ young from a previous season who are delaying their own reproductive careers, while others are fully adult birds (who help out in about 18 percent of all feedings). Some nonbreeding youngsters, however, do not help their parents. Sociable Weavers may participate in nonmonogamous heterosexual mountings (in addition to the homosexual matings described above). Although most birds are probably faithful to their partners, some males in captivity have been observed mounting and copulating with females other than their mates. Female Red Bishops occasionally refuse to allow a male to mount them, vigorously pecking and displaying threat postures to repel him. In addition, males often court Bishops of other species, who are not usually attracted by such interspecies displays. Finally, female Red Bishops have been observed cannibalizing both their own and others’ nests, eating some or all of the eggs.

Other Species

Adult male Red-shouldered Widowbirds (Euplectes axillaris) also sometimes court younger males.

Sources

*asterisked references discuss homosexuality/transgender

*Collias, E. C, and N. E. Collias (1980) “Individual and Sex Differences in Behavior of the Sociable Weaver Philetairus socius.” In D. N. Johnson, ed., Proceedings of the Fourth Pan- African Ornithological Congress (Seychelles, 1976), pp. 243—51. Johannesburg: Southern African Ornithological Society.

*———(1978) “Nest Building and Nesting Behavior of the Sociable Weaver Philetairus socius.” Ibis 120:1—15.

*Collias, N. E., and E. C. Collias (1980) “Behavior of the Gray-capped Social Weaver (Psuedonigrita arnaudi) in Kenya.” Auk 97:213—26.

Craig, A. J. F. K. (1982) “Mate Attraction and Breeding Success in the Red Bishop.” Ostrich 53:246-48.

*———(1980) “Behavior and Evolution in the Genus Euplectes.” Journal fur Ornithologie 121:144—61.

*———(1974) “Reproductive Behavior of the Male Red Bishop Bird.” Ostrich 45:149—60.

Craig, A. J. F. K., and A. J. Manson (1981) “Sexing Euplectes Species by Wing- Length.” Ostrich 52:9—16.

Maclean, G. L. (1973) “The Sociable Weaver.” Ostrich 44:176—261.

Roberts, C. (1988) “Little Bishop Birds (Euplectes orix) in a Lafia Garden—Tom, Dick, Harry, and Fred.” Nigerian Field 53:11—22.

Skead, C. J. (1959) “A Study of the Redshouldered Widowbird Coliuspasser axillaris axillaris (Smith).” Ostrich 30:13—21.

———(1956) “A Study of the Red Bishop.” Ostrich 27:112—26.

Woodall, P. F. (1971) “Notes on a Rhodesian Colony of the Red Bishop.” Ostrich 42:205—10.

HOUSE SPARROW, BROWN-HEADED COWBIRD

IDENTIFICATION: The familiar black-bibbed sparrow; Cowbird is iridescent black with a dark brown head. DISTRIBUTION: Throughout most of North and South America, Eurasia (House Sparrow); North and Central America (Cowbird). HABITAT: Woodland, prairie, farmland, human habitation. STUDY AREAS: Near Stillwater, Oklahoma, and Long Island, New York; subspecies M.a. ater and M.a. artemisiae.

WATTLED STARLING

IDENTIFICATION: Light gray plumage, black wings and tail, and (in some birds) bare yellow head and fleshy black wattles. DISTRIBUTION: Eastern and southern Africa. HABITAT: Savanna, grassland, woodland. STUDY AREAS: University of Mainz and in Nieder-Olm, Germany.

Social Organization

Wattled Starlings usually associate in small, nomadic flocks, although up to a thousand birds may gather together to pursue locust swarms. Similarly, breeding colonies may contain thousands of nests when locusts are available, but usually birds nest in smaller groups containing a maximum of 400 pairs. Most individuals form monogamous pair-bonds, as do House Sparrows (who also generally nest in colonies). Brown-headed Cowbirds have a highly variable mating system: in many populations birds form (usually monogamous) pair-bonds, while in others they are promiscuous or form polygamous bonds with several individuals.

Description

Behavioral Expression: Male Brown-headed Cowbirds sometimes solicit homosexual copulations from male House Sparrows. Cowbirds commonly invite birds of other species to preen them, but occasionally an interspecies encounter includes homosexual mounting when a House Sparrow is involved. This extraordinary behavior typically begins with a male Cowbird adopting a characteristic HEAD-DOWN posture next to a Sparrow, in which he bows his head, touching his lower bill to his breast feathers