Biological Exuberance: Animal Homosexuality and Natural Diversity

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*———(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 für Ornithologie 121:144—61.

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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.

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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 while crouching slightly and raising his wings a bit at the shoulders. The House Sparrow then mounts the Cowbird, grasping his head feathers in his beak while attempting to copulate. If he shows signs of leaving or lack of interest after a single mounting, the Cowbird will immediately resume the invitation posture next to him, insistently nudging the Sparrow with his head and persistently following him until he mounts again. This may continue for an extended time, with repeated homosexual mountings (five or more) occurring in a single session.